Publications

facile enzymatic aldol reactions with dihydroxyacetone in the presence of arsenate.	aldol reactions of in situ formed dihydroxyacetone arsenate with different aldehydes were catalyzed by bacterial d-fructose-1,6-bisphosphate aldolase (frua). aldolases from bacteria were found to be much more stable and active than frua from rabbit muscle. arsenate acts as a phosphate mimic and can, in principle, be used in catalytic amounts. the use of inorganic arsenate and dihydroxyacetone afforded high yields with hydrophobic aldehydes. cosolvents increased the solubility of hydrophobic alde ...	2001	11421774
a novel gene from myxococcus xanthus that facilitates membrane translocation of an extracellular endoglucanase in escherichia coli?	expression in escherichia coli of the myxococcus xanthus gene cela, which encodes an extracellular endoglucanase, resulted in cela being distributed between cytoplasm, periplasm and membrane. the presence of an adjacent open reading frame downstream from the full cela gene, or the absence of a putative lipoprotein signal sequence, confined cela distribution to the periplasm and membrane, or to the cytoplasm and periplasm, respectively.	2001	11446517
genetic studies of mrp, a locus essential for cellular aggregation and sporulation of myxococcus xanthus.	under starvation conditions, myxococcus xanthus undergoes a complex developmental process which includes cellular aggregation and sporulation. a transposon insertion mutant (the tn5-omega280 mutant) with defects in both aggregation and sporulation was analyzed in this study. the tn5-omega280 mutant was found to have a disrupted ntrc-like response regulator designated myxococcus regulatory protein b (mrpb). further sequencing analyses revealed a histidine kinase homolog (mrpa) immediately upstrea ...	2001	11466282
alternate routes to conformational specificity in a greek key beta barrel protein.	the n-terminal domain of protein s, a greek key calcium-binding protein from myxococcus xanthus, forms an atypical molten globule in the calcium-free state. the structure of this state is characterized by significant conformational fluctuations, which are localized to a subdomain that is not contiguous along the polypeptide chain. the conformational instability of this subdomain appears to arise from repulsive electrostatic interactions of four acidic side chains that are clustered together but ...	2001	11532002
domain architecture of a high mobility group a-type bacterial transcriptional factor.	myxococcus xanthus transcriptional factor card participates in carotenogenesis and fruiting body formation. it is the only reported prokaryotic protein having adjacent "at-hook" dna-binding and acidic regions characteristic of eukaryotic high mobility group a (hmga) proteins. the latter are small, unstructured, nonhistone nuclear proteins that function as architectural factors to remodel dna and chromatin structure and modulate various dna binding activities. we find card to be predominantly dim ...	2001	11533063
bacterial gliding motility: multiple mechanisms for cell movement over surfaces.	the mechanisms responsible for bacterial gliding motility have been a mystery for almost 200 years. gliding bacteria move actively over surfaces by a process that does not involve flagella. gliding bacteria are phylogenetically diverse and are abundant in many environments. recent results indicate that more than one mechanism is needed to explain all forms of bacterial gliding motility. myxococcus xanthus "social gliding motility" and synechocystis gliding are similar to bacterial "twitching mot ...	2001	11544349
glycerol 3-phosphate inhibits swarming and aggregation of myxococcus xanthus.	we have cloned a gene of myxococcus xanthus with similarities to the permease for glycerol 3-phosphate (g3p) of other bacteria. expression of the gene increased significantly during the first hours of starvation. swarming of the wild-type strain was inhibited and aggregation was delayed by g3p. conversely, a deltaglpt strain aggregated even on rich medium. these results indicate that g3p may function to regulate the timing of aggregation in m. xanthus.	2001	11567014
an unusual beta-ketoacyl:acyl carrier protein synthase and acyltransferase motifs in tak, a putative protein required for biosynthesis of the antibiotic ta in myxococcus xanthus.	the antibiotic ta of myxococcus xanthus is produced by a type-i polyketide synthase mechanism. previous studies have indicated that ta genes are clustered within a 36-kb region. the chemical structure of ta indicates the need for several post-modification steps, which are introduced to form the final bioactive molecule. these include three c-methylations, an o-methylation and a specific hydroxylation. in this study, we describe the genetic analysis of tak, encoding a specific polyketide beta-ket ...	2001	11583847
radiation-mediated control of drug delivery.	clinical trials of radiotherapy to control drug delivery were initiated in 1999 at vanderbilt university. the initial studies exploited the findings that platelets are activated in tumor blood vessels after high-dose irradiation as used in radiosurgery and high-dose-rate brachytherapy. platelets labeled with 111in showed binding in tumor blood vessels. however, the platelet labeling process caused platelets to also accumulate in the spleen. that clinical trial was closed, and subsequent clinical ...	2001	11586099
heat-shock-induced proteins from myxococcus xanthus.	optimal conditions for two-dimensional gel electrophoresis of total cellular proteins from myxococcus xanthus were established. using these conditions, we analyzed protein patterns of heat-shocked m. xanthus cells. eighteen major spots and 15 minor spots were found to be induced by heat shock. from n-terminal sequences of 15 major spots, dnak, groel, groes, alkyl hydroperoxide reductase, aldehyde dehydrogenase, succinyl coenzyme a (coa) synthetase, 30s ribosomal protein s6, and atp synthase alph ...	2001	11591671
analyses of mrp genes during myxococcus xanthus development.	myxococcus xanthus is a gram-negative soil bacterium that undergoes development under starvation conditions. our previous study identified a new genetic locus, mrp, which is required for both fruiting body formation and sporulation. the locus encodes two transcripts: mrpab, which consists of a histidine kinase and an ntrc-like response regulator, and mrpc, a cyclic amp receptor protein family transcription activator. in this study, we used genetic and biochemical analyses to investigate the poss ...	2001	11698359
gida is an fad-binding protein involved in development of myxococcus xanthus.	a gene encoding a homologue of the escherichia coli gida protein (glucose-inhibited division protein a) lies immediately upstream of aglu, a gene encoding a wd-repeat protein required for motility and development in myxococcus xanthus. the gida protein of m. xanthus shares about 48% identity overall with the small (approximately equal to 450 amino acid) form of gida from eubacteria and about 24% identity overall with the large (approximately equal to 620 amino acid) form of gida from eubacteria ...	2001	11703671
identification of a developmental chemoattractant in myxococcus xanthus through metabolic engineering.	fruiting body formation of myxococcus xanthus requires the ordered migration of tens of thousands of cells by using a form of surface motility known as gliding and chemical signal(s) that have yet to be elucidated. directed movement is regulated by phosphatidylethanolamine (pe) purified from m. xanthus cell membranes. because the purified pe preparation contains a remarkably diverse mixture of fatty acids, metabolic engineering was used to elucidate the biologically active fatty acid component. ...	2001	11717456
light-induced carotenogenesis in myxococcus xanthus: evidence that cars acts as an anti-repressor of cara.	in the bacterium myxococcus xanthus, carotenoids are produced in response to illumination, as a result of expression of the crt carotenoid biosynthesis genes. the majority of crt genes are clustered in the crtebdc operon, which is repressed in the dark by cara. genetic data suggest that, in the light, cars is synthesized and achieves activation of the crtebdc operon by removing the repressive action of cara. as cars contains no known dna-binding motif, the relief of cara-mediated repression was ...	2001	11722744
lens crystallins and their microbial homologs: structure, stability, and function.	abg-crystallins are the major protein components in the vertebrate eye lens--a as a molecular chaperone and b and g as structural proteins. surprisingly, the latter two share some structural characteristics with a number of microbial stress proteins. the common denominator is not only the greek key topology of their polypeptide chains but also their high intrinsic stability, which, in certain microbial crystallin homologs, is further enhanced by high-affinity ca2+-binding. recent studies of natu ...	2001	11724156
mgla and mglb of treponema denticola; similarity to abc transport and spa genes.	the mgla and mglb genes (td-mgla and td-mglb) of the oral spirochete treponema denticola were sequenced. these two t. denticola genes are highly homologous to the e. coli and treponema pallidum mgla and mglb genes which are part of the three gene beta-methylgalactoside transport operon, mglbac. both td-mgla and td-mglb are also homologous to the high affinity abc-type transporters for ribose and arabinose, and surface presentation antigens (spa) locus, part of the type iii secretion systems in e ...	2000	11328650
the myxococcus xanthus wbgb gene encodes a glycosyltransferase homologue required for lipopolysaccharide o-antigen biosynthesis.	myxococcus xanthus is a gram-negative soil bacterium that initiates a complex developmental program in response to starvation. a transposon insertion (tn5-lac omega109) mutant with developmental deficiencies was isolated and characterized in this study. a strain containing this insertion mutation in an otherwise wild-type background showed delayed developmental aggregation for about 12 h and sporulated at 1-2% of the wild-type level. tn5-lac omega109 was found to have disrupted the m. xanthus wb ...	2000	11195095
pattern formation: fruiting body morphogenesis in myxococcus xanthus.	when myxococcus xanthus cells are exposed to starvation, they respond with dramatic behavioral changes. the expansive swarming behavior stops and the cells begin to aggregate into multicellular fruiting bodies. the cell-surface-associated c-signal has been identified as the signal that induces aggregation. recently, several of the components in the c-signal transduction pathway have been identified and behavioral analyses are beginning to reveal how the c-signal modulates cell behavior. together ...	2000	11121786
[expression, purification and characterization of frua, a transcription factor in myxococcus xanthus].	frua is a transcription factor essential for the development of myxocoxccus xanthus. gene encoding frua with a poly-histidine tag was expressed in e. coli and simply purified by chromatography on nickel column. data from gel retardation assay suggest that frua regulates transcription of target genes in collaboration with other factors.	2000	12548932
[isolation and identification of myxobacteria].	this paper reported that the authors isolated large numbers of myxobacteria from more than 100 samples collected in many places of china. more than 400 pure strains were obtained. these strains belonged to 10 genera of myxococcales. the most frequent genera isolated were myxococcus, sorangium, corallococcus, and cystobacter. melittangium was seldom isolated. no chondromyces and haploangium were found.	2000	12549062
disruption of alda influences the developmental process in myxococcus xanthus.	previously, we identified a gene (alda) from myxococcus xanthus, which we suggested encoded the enzyme alanine dehydrogenase on the basis of similarity to known ald protein sequences (m. j. ward, h. lew, a. treuner-lange, and d. r. zusman, j. bacteriol. 180:5668-5675, 1998). in this study, we have confirmed that alda does encode a functional alanine dehydrogenase, since it catalyzes the reversible conversion of alanine to pyruvate and ammonia. whereas an alda gene disruption mutation did not sig ...	2000	10629210
the stringent response in myxococcus xanthus is regulated by soce and the csga c-signaling protein.	myxococcus xanthus fruiting body development is induced by amino acid limitation. the decision to grow or develop is established by the rela-dependent stringent response and a-signaling. we identified two new members of this regulatory hierarchy, soce and the c-signaling gene csga. soce depletion arrests growth and induces sporulation under conditions that normally favor growth as well as curtailing dna and stable rna synthesis, inhibiting cell elongation, and inducing accumulations of the strin ...	2000	10691740
the asge locus is required for cell-cell signalling during myxococcus xanthus development.	in response to starvation, myxococcus xanthus undergoes a multicellular developmental process that produces a dome-shaped fruiting body structure filled with differentiated cells called myxospores. two insertion mutants that block the final stages of fruiting body morphogenesis and reduce sporulation efficiency were isolated and characterized. dna sequence analysis revealed that the chromosomal insertions are located in open reading frames orf2 and asge, which are separated by 68 bp. the sporula ...	2000	10692158
evolution of arginine biosynthesis in the bacterial domain: novel gene-enzyme relationships from psychrophilic moritella strains (vibrionaceae) and evolutionary significance of n-alpha-acetyl ornithinase.	in the arginine biosynthetic pathway of the vast majority of prokaryotes, the formation of ornithine is catalyzed by an enzyme transferring the acetyl group of n-alpha-acetylornithine to glutamate (ornithine acetyltransferase [oatase]) (argj encoded). only two exceptions had been reported-the enterobacteriaceae and myxococcus xanthus (members of the gamma and delta groups of the class proteobacteria, respectively)-in which ornithine is produced from n-alpha-acetylornithine by a deacylase, acetyl ...	2000	10692366
a sigma(54) activator protein necessary for spore differentiation within the fruiting body of myxococcus xanthus.	insertion of an internal dna fragment into the act1 gene, which encodes one of several sigma(54)-activator proteins in myxococcus xanthus, produced a mutant defective in fruiting body development. while fruiting-body aggregation appears normal in the mutant, it fails to sporulate (<10(-6) the wild-type number of viable spores). the a and c intercellular signals, which are required for sporulation, are produced by the mutant. but, while it produces a-factor at levels as high as that of the wild t ...	2000	10762243
bacterial cheaters.		2000	10766222
developmental cheating in the social bacterium myxococcus xanthus.	cheating is a potential problem in any social system that depends on cooperation and in which actions that benefit a group are costly to individuals that perform them. genetic mutants that fail to perform a group-beneficial function but that reap the benefits of belonging to the group should have a within-group selective advantage, provided that the mutants are not too common. here we show that social cheating exists even among prokaryotes. the bacterium myxococcus xanthus exhibits several socia ...	2000	10766241
effect of culture conditions on the formation of struvite by myxococcus xanthus.	the amount of struvite (mgnh4po4 x 6h2o) produced by myxococcus xanthus as well as the culture parameter values (ph, total phosphorus, total kjeldahl nitrogen) were dependent on the culture medium used. struvite formation started during the exponential phase and the maximum concentration was observed at the beginning of stationary growth phase. the addition of each medium component to the liquid culture influenced the amount of crystal produced. this amount did not depend on the ph increase duri ...	2000	10789967
purification and characterization of a novel lectin from a freshwater cyanobacterium, oscillatoria agardhii.	in the survey of 14 species of laboratory-cultured cyanobacteria for hemagglutinins, we newly detected the activity in two species, oscillatoria agardhii, strain nies-204, and phormidium foveolarum, strain nies-503. from the extract of o. agardhii, which showed the highest activity with trypsin-treated erythrocytes of rabbit, a lectin was purified to homogeneity by the combination of precipitation with (nh4)2so4, gel filtration, hydrophobic chromatography and reverse phase chromatography. the pu ...	2000	10817903
aglu, a protein required for gliding motility and spore maturation of myxococcus xanthus, is related to wd-repeat proteins.	the aglu gene of myxococcus xanthus encodes a protein similar to het-e1 (vegetative incompatibility) from podospora anserina, acylaminoacyl-peptidase from bacillus subtilis, and tolb from escherichia coli. these proteins all have evenly spaced spdg repeats that are characteristic of a larger motif called the wd-repeat. the wd-repeat is predicted to form a beta-propeller structure that mediates the assembly of heteromeric protein complexes. aglu has a consensus lipoprotein attachment motif that i ...	2000	10844655
a common step for changing cell shape in fruiting body and starvation-independent sporulation of myxococcus xanthus.	myxococcus xanthus can sporulate in either of two ways: at the end of the program of fruiting body development or after exposure of growing cells to certain reagents such as concentrated glycerol. fruiting body sporulation requires starvation, while glycerol sporulation requires rapid growth, and since the two types of spores are structurally somewhat different, it has generally been assumed that the two processes are different. however, a tn5 lac insertion mutation, omega7536, has been isolated ...	2000	10852889
developmental cheating and the evolutionary biology of dictyostelium and myxococcus.		2000	10878115
fructose utilization and pathogenicity of spiroplasma citri: characterization of the fructose operon.	transposon tn4001 mutagenesis of spiroplasma citri wild-type (wt) strain gii-3 led to the isolation and characterization of non-phytopathogenic mutant gmt 553. in this mutant, transposon tn4001 is inserted within the first gene of the fructose operon. this operon comprises three genes. the first gene (frur) codes for a putative transcriptional regulator protein belonging to the deoxyribonucleoside repressor (deor) family. sequence similarities and functional complementation of mutant gmt 553 wit ...	2000	10903438
identification and characterization of genes required for early myxococcus xanthus developmental gene expression.	starvation and cell density regulate the developmental expression of myxococcus xanthus gene 4521. three classes of mutants allow expression of this developmental gene during growth on nutrient agar, such that colonies of strains containing a tn5 lac omega4521 fusion are lac(+). one class of these mutants inactivates sasn, a negative regulator of 4521 expression; another class activates sass, a sensor kinase-positive regulator of 4521 expression; and a third class blocks lipopolysaccharide (lps) ...	2000	10913090
spatial control of cell differentiation in myxococcus xanthus.	myxococcus xanthus develops species-specific multicellular fruiting bodies. starting from a uniform mat of cells, some cells enter into nascent fruiting body aggregates, whereas other cells remain outside. the cells within the fruiting body differentiate from rods into spherical, heat-resistant spores, whereas the cells outside the aggregates, called peripheral cells, remain rod-shaped. early developmentally regulated genes are expressed in peripheral cells as well as by cells in the fruiting bo ...	2000	10922065
the myxococcus xanthus soce and csga genes are regulated by the stringent response.	disruption of the myxococcus xanthus soce gene bypasses the requirement for the cell contact-dependent c-signalling system mediated by csga and restores fruiting body morphogenesis and spore differentiation. the soce gene has been identified by genetic complementation, cloned and sequenced. soce is highly basic, unique and is predicted to be a soluble protein with a molecular size of 53. 6 kda. the soce and csga genes have opposite transcription patterns during the m. xanthus life cycle. soce ex ...	2000	10972801
fructose operon mutants of spiroplasma citri.	fructose-negative mutants of spiroplasma citri wild-type strain gii-3 were selected by two methods. the first method is based on the selection of spontaneous xylitol-resistant mutants, xylitol being a toxic fructose analogue. five such mutants were obtained, but only one, xyl3, was unable to use fructose and had no phosphoenolpuryvate:fructose phosphotransferase system (fructose-pts) activity. amplification and sequencing of the fructose permease gene of mutant xyl3 revealed the presence of an a ...	2000	10974110
programmed death in bacteria.	programmed cell death (pcd) in bacteria plays an important role in developmental processes, such as lysis of the mother cell during sporulation of bacillus subtilis and lysis of vegetative cells in fruiting body formation of myxococcus xanthus. the signal transduction pathway leading to autolysis of the mother cell includes the terminal sporulation sigma factor esigma(k), which induces the synthesis of autolysins cwlc and cwlh. an activator of autolysin in this and other pcd processes is yet to ...	2000	10974124
molecular cloning and characterization of two genes for the biotin carboxylase and carboxyltransferase subunits of acetyl coenzyme a carboxylase in myxococcus xanthus.	we have cloned a dna fragment from a genomic library of myxococcus xanthus using an oligonucleotide probe representing conserved regions of biotin carboxylase subunits of acetyl coenzyme a (acetyl-coa) carboxylases. the fragment contained two open reading frames (orf1 and orf2), designated the accb and acca genes, capable of encoding a 538-amino-acid protein of 58.1 kda and a 573-amino-acid protein of 61.5 kda, respectively. the protein (acca) encoded by the acca gene was strikingly similar to b ...	2000	10986250
type iv pilus of myxococcus xanthus is a motility apparatus controlled by the frz chemosensory system.	although flagella are the best-understood means of locomotion in bacteria [1], other bacterial motility mechanisms must exist as many diverse groups of bacteria move without the aid of flagella [2-4]. one unusual structure that may contribute to motility is the type iv pilus [5,6]. genetic evidence indicates that type iv pili are required for social gliding motility (s-motility) in myxococcus, and twitching motility in pseudomonas and neisseria [6,7]. it is thought that type iv pili may retract ...	2000	10996798
social motility in myxococcus xanthus requires frzs, a protein with an extensive coiled-coil domain.	gliding motility in the developmental bacterium myxococcus xanthus involves two genetically distinct motility systems, designated adventurous (a) and social (s). directed motility responses, which facilitate both vegetative swarming and developmental aggregation, additionally require the 'frizzy' (frz) signal transduction pathway. in this study, we have analysed a new gene (frzs), which is positioned upstream of the frza-f operon. insertion mutations in frzs caused both vegetative spreading and ...	2000	10998168
myxococcus xanthus dif genes are required for biogenesis of cell surface fibrils essential for social gliding motility.	myxococcus xanthus social (s) gliding motility has been previously reported by us to require the chemotaxis homologues encoded by the dif genes. in addition, two cell surface structures, type iv pili and extracellular matrix fibrils, are also critical to m. xanthus s motility. we have demonstrated here that m. xanthus dif genes are required for the biogenesis of fibrils but not for that of type iv pili. furthermore, the developmental defects of dif mutants can be partially rescued by the additio ...	2000	11004179
myxococcus xanthus fibril appendages are essential for excitation by a phospholipid attractant.	isolated (a-motile) myxococcus xanthus cells glide over solid surfaces and display excitation, a suppression of direction reversals, when presented with phosphatidylethanolamine (pe) purified from its own membranes or synthetic dilauroyl pe and dioleoyl pe. although the mechanism of pe signal transduction is unknown, we hypothesized that m. xanthus might use surface-associated factors to detect exogenous pe to prevent endogenous lipids from self-stimulating the sensory system. peritrichous prote ...	2000	11016978
evolution of viruses by acquisition of cellular rna or dna nucleotide sequences and genes: an introduction.	the origins of virus evolution may be traced to archeabacteria since inouye and inouye (6) discovered a retroelement with a gene for reverse transcriptase in the bacterial genome and in the satellite, multiple copy single stranded dna (msdna) in the soil bacterium myxococcus xanthus. it was possible (8) to define the evolution of retroelements in eukaryotic cells of plants, insects (gypsy retrovirus) and vertebrates. the replication of rna viruses in eukaryotic cells allowed for the viral rna ge ...	2000	11022785
cloning and expression of isocitrate lyase from human round worm strongyloides stercoralis.	a full length cdna (1463 bp) encoding isocitrate lyase (ec 4.1.3.1) of strongyloides stercoralis is described. the nucleotide sequence of this insert identified a cdna coding for the isocitrate lyase. the conceptually translated amino acid sequence of the open reading frame for s. stercoralis isocitrate lyase encodes a 450 amino acid residue protein with an apparent molecular weight of 50 kda and a predicted pl of 6.39. the sequence is 69% a/t, reflecting a characteristic a/t codon bias of s. st ...	2000	11031761
effect of the adhesive antibiotic ta on adhesion and initial growth of e. coli on silicone rubber.	catheter-associated urinary tract infection is the most common nosocomial infection, and contributes to patient morbidity and mortality. we investigated the effect that the ta adhesive antibiotic had on adhesion and initial growth in urine of escherichia coli on silicone rubber. the ta antibiotic had reduced adhesion, and inhibited initial growth of the bacteria on the surface. since adhesion and initial growth on the surface are an essential part of biofilm formation and subsequent infection, w ...	2000	11040435
[frua, a transcription factor in myxococus xamthus, regulates transcription of target genes in collaboration with the associated protein frub].	many developmental genes are regulated by frua, a transcription factor essential for the development of myxococus xamthus. another protein, designated frub, was purified from myxobacteria by its affinity to frua. frub could be phosphorylated by protein kinase(s) located in cell membrane. gel shift assay showed that frua regulates transcription of target genes in collaboration with phosphorylated frub. this study may shed light on the molecular mechanisms of regulatory network involved in the dev ...	2000	11057053
phenotypic analyses of frz and dif double mutants of myxococcus xanthus.	myxococcus xanthus is a gram-negative gliding bacterium that aggregates and develops into multicellular fruiting bodies in response to starvation. two chemosensory systems (frz and dif), both of which are homologous to known chemotaxis proteins, were previously identified through characterization of various developmental mutants. this study aims to examine the interaction between these two systems since both of them are required for fruiting body formation of m. xanthus. through detailed phenoty ...	2000	11064197
mechanisms of apoptosis.	programmed cell death plays critical roles in a wide variety of physiological processes during fetal development and in adult tissues. in most cases, physiological cell death occurs by apoptosis as opposed to necrosis. defects in apoptotic cell death regulation contribute to many diseases, including disorders where cell accumulation occurs (cancer, restenosis) or where cell loss ensues (stroke, heart failure, neurodegeneration, aids). in recent years, the molecular machinery responsible for apop ...	2000	11073801
developmental aggregation of myxococcus xanthus requires frga, an frz-related gene.	myxococcus xanthus is a gram-negative bacterium which has a complex life cycle that includes multicellular fruiting body formation. frizzy mutants are characterized by the formation of tangled filaments instead of hemispherical fruiting bodies on fruiting agar. mutations in the frz genes have been shown to cause defects in directed motility, which is essential for both vegetative swarming and fruiting body formation. in this paper, we report the discovery of a new gene, called frga (for frz-rela ...	2000	11073903
control of asge expression during growth and development of myxococcus xanthus.	one of the earliest events in the myxococcus xanthus developmental cycle is production of an extracellular cell density signal called a-signal (or a-factor). previously, we showed that cells carrying an insertion in the asge gene fail to produce normal levels of this cell-cell signal. in this study we found that expression of asge is growth phase regulated and developmentally regulated. several lines of evidence indicate that asge is cotranscribed with an upstream gene during development. using ...	2000	11073904
identification of a substrate for pkn2, a protein ser/thr kinase from myxococcus xanthus by a novel method for substrate identification.	eukaryotic cells contain a large number of protein ser/ thr kinases, which play important roles in signal transduction required for cell proliferation, differentiation, and stress response and adaptation. it is also known that some prokaryotes contain a family of protein ser/thr kinases. a major challenge in the characterization of these kinases is how to identify their specific substrates. here we developed such a method using a protein ser/thr kinase, pkn2 from myxococcus xanthus, a gram-negat ...	2000	11075932
a large family of eukaryotic-like protein ser/thr kinases of myxococcus xanthus, a developmental bacterium.	myxococcus xanthus is a gram-negative bacterium that forms multicellular fruiting bodies upon starvation. here, we demonstrate that it contains at least 13 eukaryotic-like protein ser/thr kinases (pkn1 to pkn13) individually having unique features. all contain the kinase domain of approximately 280 residues near the n-terminal end, which share highly conserved features in eukaryotic ser/thr kinases. the kinase domain is followed by a putative regulatory domain consisting of 185 to 692 residues. ...	2000	11087177
inorganic polyphosphate kinase and adenylate kinase participate in the polyphosphate:amp phosphotransferase activity of escherichia coli.	polyphosphate kinase (ppk), responsible for the processive synthesis of inorganic polyphosphate (polyp) from atp in escherichia coli, can transfer in reverse the terminal phosphate residue of polyp to adp to yield atp. polyp also serves as a donor in a polyp:amp phosphotransferase (pap) activity observed in extracts of acinetobacter johnsonii and myxococcus xanthus. we have found that overexpression of the gene encoding ppk results in a large enhancement of pap activity in e. coli. the pap activ ...	2000	11106368
mutations that confer resistance to 2-deoxyglucose reduce the specific activity of hexokinase from myxococcus xanthus.	the glucose analog 2-deoxyglucose (2dglc) inhibits the growth and multicellular development of myxococcus xanthus. mutants of m. xanthus resistant to 2dglc, designated hex mutants, arise at a low spontaneous frequency. expression of the escherichia coli glk (glucokinase) gene in m. xanthus hex mutants restores 2dglc sensitivity, suggesting that these mutants arise upon the loss of a soluble hexokinase function that phosphorylates 2dglc to form the toxic intermediate, 2-deoxyglucose-6-phosphate. ...	1999	10094702
an erythromycin resistance cassette and mini-transposon for constructing transcriptional fusions to cat.	a new cassette (er-cm cassette) and mini-transposon (mtn) (tnmaxercm) based on the previously described mtn, tnmax2 [haas et al., gene 130, 23-31.], have been constructed. the cassette and mtn make use of an erythromycin resistance (err) marker encoded by ermc'. both the er-cm cassette and tnmaxercm also carry a promoterless cat gene to allow the construction of transcriptional fusions and the measurement of transcriptional activity by assaying for chloramphenicol acetyltransferase. we show the ...	1999	10095104
kr025, a new cytotoxic compound from myxococcus fulvus.	a new bithiazole, kr-025 (1), was isolated from myxococcus fulvus. its structure was elucidated by spectroscopic analysis. in addition to 1, the strain produced relatively large quantities of a second, closely related antibiotic, myxothiazol. these compounds demonstrated potent cytotoxicity against human tumor cells.	1999	10096868
gliding mutants of myxococcus xanthus with high reversal frequencies and small displacements.	myxococcus xanthus cells move on a solid surface by gliding motility. several genes required for gliding motility have been identified, including those of the a- and s-motility systems as well as the mgl and frz genes. however, the cellular defects in gliding movement in many of these mutants were unknown. we conducted quantitative, high-resolution single-cell motility assays and found that mutants defective in mglab or in cglb, an a-motility gene, reversed the direction of gliding at frequencie ...	1999	10198026
secretion of atp-utilizing enzymes, nucleoside diphosphate kinase and atpase, by mycobacterium bovis bcg: sequestration of atp from macrophage p2z receptors?	mycobacterium bovis bcg secretes two atp-scavenging enzymes, nucleoside diphosphate kinase (ndk) and atpase, during growth in middlebrook 7h9 medium. in synthetic sauton medium without any protein supplements, there is less secretion of these two enzymes unless proteins such as bovine serum albumin (bsa), ovalbumin or extracts of macrophages are added to the medium. there is a gradient of activity among various proteins in triggering the induction of secretion of these two enzymes. other mycobac ...	1999	10200955
type iv pili and cell motility.	type iv pili (tfp) mediate the movement of bacteria over surfaces without the use of flagella. these movements are known as social gliding in myxococcus xanthus and twitching in organisms such as pseudomonas aeruginosa and neisseria gonorrhoeae. tfp are localized polarly. type iv pilins have a signature n-terminal domain, which forms a coiled-coil with other monomer units to polymerize a pilus fibre. at least 10 more proteins at the base of the fibre are conserved; they are related to the type i ...	1999	10216854
diffusion through agar blocks of finite dimensions: a theoretical analysis of three systems of practical significance in microbiology.	a number of experimental methods in biology depend on the kinetics of diffusion of a substance through a gel. this paper reviews the diffusion equations, gives the experimental limitations for some useful cases, and presents computer simulations for cases that cannot be treated analytically. while double diffusion is not considered, three single-diffusion situations are treated. (1) systems for the study of chemotaxis in the gliding bacterium myxococcus xanthus. experimental designs used for thi ...	1999	10217498
the cell surface-associated intercellular c-signal induces behavioral changes in individual myxococcus xanthus cells during fruiting body morphogenesis.	fruiting body formation in myxococcus xanthus depends on ordered changes in cell movements from swarming to aggregation in response to starvation. we show that appropriately starved individual cells change behavior during fruiting body formation. specifically, from the time of initiation of aggregation, individual wild-type cells began to move with increased gliding speeds, the duration of the mean gliding interval increased, and the stop frequency decreased whereas the duration of the mean stop ...	1999	10220413
site-specific recombination of temperate myxococcus xanthus phage mx8: genetic elements required for integration.	like most temperate bacteriophages, phage mx8 integrates into a preferred locus on the genome of its host, myxococcus xanthus, by a mechanism of site-specific recombination. the mx8 int-attp genes required for integration map within a 2.2-kilobase-pair (kb) fragment of the phage genome. when this fragment is subcloned into a plasmid vector, it facilitates the site-specific integration of the plasmid into the 3' ends of either of two tandem trnaasp genes, trnd1 and trnd2, located within the attb ...	1999	10383974
regulated exopolysaccharide production in myxococcus xanthus.	myxococcus xanthus fibrils are cell surface-associated structures composed of roughly equal amounts of polysaccharide and protein. the level of m. xanthus polysaccharide production under different conditions in the wild type and in several mutants known to have alterations in fibril production was investigated. wild-type exopolysaccharide increased significantly as cells entered the stationary phase of growth or upon addition of ca2+ to growing cells, and the polysaccharide-induced cells exhibit ...	1999	10049381
the domains of protein s from myxococcus xanthus: structure, stability and interactions.	protein s from myxococcus xanthus is a member of the beta gamma-crystallin superfamily. its n and c-terminal domains (nps and cps, respectively) show a high degree of structural similarity and possess the capacity to bind two calcium ions per domain. for nps, their positions were determined by x-ray diffraction at 1.8 a resolution, making use of molecular replacement with the nmr structure as search model. the overall topology of nps is found to be practically the same as in complete protein s. ...	1999	10064714
cloning and characterization of a myxococcus xanthus cytochrome p-450 hydroxylase required for biosynthesis of the polyketide antibiotic ta.	the antibiotic ta, a complex macrocyclic polyketide of myxococcus xanthus, is produced, like many other polyketides, through successive condensations of acetate by a type i polyketide synthase (pks) mechanism. the chemical structure of this antibiotic and the mechanism by which it is synthesized indicate the need for several post-modification steps, such as a specific hydroxylation at c-20. previous studies have shown that several genes, essential for ta biosynthesis, are clustered in a region o ...	1999	10072767
site-specific recombination of temperate myxococcus xanthus phage mx8: regulation of integrase activity by reversible, covalent modification.	temperate myxococcus xanthus phage mx8 integrates into the attb locus of the m. xanthus genome. the phage attachment site, attp, is required in cis for integration and lies within the int (integrase) coding sequence. site-specific integration of mx8 alters the 3' end of int to generate the modified intx gene, which encodes a less active form of integrase with a different c terminus. the phage-encoded (int) form of integrase promotes attp x attb recombination more efficiently than attr x attb, at ...	1999	10383975
scoc regulates peptide transport and sporulation initiation in bacillus subtilis.	oligopeptides are transported into bacillus subtilis by two abc transport systems, app and opp. transcription of the operon encoding the opp system was found to occur during exponential growth, whereas the app operon was induced at the onset of stationary phase. transcription of both operons was completely curtailed by overproduction of the scoc regulator from a multicopy plasmid and was enhanced in strains with the scoc locus deleted. scoc, a member of the marr family of transcription regulator ...	1999	10383984
cell fate and organogenesis in bacteria.	intercellular signaling through the notch receptor and its ligands leads to the spatial differentiation of cell fate in vertebrates and invertebrates. in myxococcus xanthus, fruiting-body development requires the transmission of a cell-bound intercellular signal by the protein called c-factor, which is functionally equivalent to the eukaryotic notch ligands. functional parallels between these two signaling systems include strong positive and negative feedback, and a consequent role in spatial di ...	1999	10390626
myxococcus cells respond to elastic forces in their substrate.	elasticotaxis describes the ability of myxococcus xanthus cells to sense and to respond to elastic forces within an agar gel on which they rest. within 5 min of the application of stress, each cell begins to reorient its long axis perpendicular to the stress force. the cells then glide in that direction, and the swarm becomes asymmetric. a quantifiable assay for the strength of elasticotaxis is based on the change in swarm shape from circular to elliptic. by using a collection of isogenic motili ...	1999	10393946
genetic and molecular analysis of cglb, a gene essential for single-cell gliding in myxococcus xanthus.	gliding movements of individual isolated myxococcus xanthus cells depend on the genes of the a-motility system (agl and cgl genes). mutants carrying defects in those genes are unable to translocate as isolated cells on solid surfaces. the motility defect of cgl mutants can be transiently restored to wild type by extracellular complementation upon mixing mutant cells with wild-type or other motility mutant cells. to develop a molecular understanding of the function of a cgl protein in gliding mot ...	1999	10400597
genetic suppression analysis of an asga missense mutation in myxococcus xanthus.	the asga gene is required for generation of extracellular a signal, which serves as a cell-density signal for fruiting body development in myxococcus xanthus. the asga protein is a histidine protein kinase and consists of a receiver domain that is conserved among response regulators of two-component signal transduction systems, followed by a histidine protein kinase domain that is conserved among sensor proteins of two-component systems. asga is thought to function in a signal transduction pathw ...	1999	10411256
molecular cloning, sequence analysis, and characterization of a penicillin-resistant dd-carboxypeptidase of myxococcus xanthus.	we have cloned a gene, pdca, from the genomic library of myxococcus xanthus with an oligonucleotide probe representing conserved regions of penicillin-resistant dd-carboxypeptidases. the amino- and carboxy-terminal halves of the predicted pdca gene product showed significant sequence similarity to n-acetylmuramoyl-l-alanine amidase and penicillin-resistant dd-carboxypeptidase, respectively. the pdca gene was expressed in escherichia coli, and the characteristics of the gene product were similar ...	1999	10419975
the correlation between morphological and phylogenetic classification of myxobacteria.	in order to determine whether morphological criteria are suitable to affiliate myxobacterial strains to species, a phylogenetic analysis of 16s rdnas was performed on 54 myxobacterial strains that represented morphologically 21 species of the genera angiococcus, archangium, chondromyces, cystobacter, melittangium, myxococcus, polyangium and stigmatella, five invalid species and three unclassified isolates. the analysis included 12 previously published sequences. the branching pattern confirmed t ...	1999	10425789
identification of the omega4499 regulatory region controlling developmental expression of a myxococcus xanthus cytochrome p-450 system.	omega4499 is the site of a tn5 lac insertion in the myxococcus xanthus chromosome that fuses lacz expression to a developmentally regulated promoter. cell-cell interactions that occur during development, including c signaling, are required for normal expression of tn5 lac omega4499. the dna upstream of the omega4499 insertion has been cloned, and the promoter has been localized. analysis of the dna sequence downstream of the promoter revealed one complete open reading frame and a second partial ...	1999	10464222
fibrils as extracellular appendages of bacteria: their role in contact-mediated cell-cell interactions in myxococcus xanthus.	social behavior in the myxobacterium myxococcus xanthus involves epicellular, peritrichous appendages called fibrils. these are polysaccharide organelles containing a set of tightly adhering proteins. it is proposed that cell-cell contact is perceived by the fibrils and is mediated by the action of a fibrillar adp-ribosyl transferase. fibrils or fibril-like organelles have also been found on a variety of other gram-negative bacteria and at least one archaeon, and may mediate cell-cell contact be ...	1999	10472185
gliding motility in bacteria: insights from studies of myxococcus xanthus.	gliding motility is observed in a large variety of phylogenetically unrelated bacteria. gliding provides a means for microbes to travel in environments with a low water content, such as might be found in biofilms, microbial mats, and soil. gliding is defined as the movement of a cell on a surface in the direction of the long axis of the cell. because this definition is operational and not mechanistic, the underlying molecular motor(s) may be quite different in diverse microbes. in fact, studies ...	1999	10477310
a nonessential signal peptidase ii (lsp) of myxococcus xanthus might be involved in biosynthesis of the polyketide antibiotic ta.	myxococcus xanthus is a gram-negative soil bacterium that produces the polyketide antibiotic ta. in this study, we describe the analysis of an m. xanthus gene which encodes a homologue of the prolipoprotein signal peptidase ii (spase ii; lsp). overexpression of the m. xanthus spase ii in escherichia coli confers high levels of globomycin resistance, confirming its function as an spase ii. the m. xanthus gene encoding the lsp homologue is nonessential for growth, as determined by specific gene di ...	1999	10482504
characterization of the chromosomal aac(6')-iz gene of stenotrophomonas maltophilia.	the aac(6')-iz gene of stenotrophomonas maltophilia bm2690 encoding an aminoglycoside 6'-n-acetyltransferase was characterized. the gene was identified as a coding sequence of 462 bp corresponding to a protein with a calculated mass of 16,506 da, a value in good agreement with that of ca. 16,000 found by in vitro coupled transcription-translation. analysis of the deduced amino acid sequence indicated that the protein was a member of the major subfamily of aminoglycoside 6'-n-acetyltransferases. ...	1999	10508008
calorimetric analysis of the ca(2+)-binding betagamma-crystallin homolog protein s from myxococcus xanthus: intrinsic stability and mutual stabilization of domains.	the betagamma-crystallin superfamily consists of a class of homologous two-domain proteins with greek-key fold. protein s, a ca(2+)-binding spore-coat protein from the soil bacterium myxococcus xanthus exhibits a high degree of sequential and structural homology with gammab-crystallin from the vertebrate eye lens. in contrast to gammab-crystallin, which undergoes irreversible aggregation upon thermal unfolding, protein s folds reversibly and may therefore serve as a model in the investigation of ...	1999	10512720
induction of beta-lactamase influences the course of development in myxococcus xanthus.	myxococcus xanthus is a gram-negative bacterium that develops in response to starvation on a solid surface. the cells assemble into multicellular aggregates in which they differentiate from rod-shaped cells into spherical, environmentally resistant spores. previously, we have shown that the induction of beta-lactamase is associated with starvation-independent sporulation in liquid culture (k. a. o'connor and d. r. zusman, mol. microbiol. 24:839-850, 1997). in this paper, we show that the chromos ...	1999	10515921
a re-examination of twitching motility in pseudomonas aeruginosa.	twitching motility is a form of solid surface translocation which occurs in a wide range of bacteria and which is dependent on the presence of functional type iv fimbriae or pili. a detailed examination of twitching motility in pseudomonas aeruginosa under optimal conditions in vitro was carried out. under these conditions (at the smooth surface formed between semi-solid growth media and plastic or glass surfaces) twitching motility is extremely rapid, leading to an overall radial rate of colony ...	1999	10537208
identification and characterization of five cspa homologous genes from myxococcus xanthus.	escherichia coli contains a large cspa family consisting of nine homologues, in which four are cold-shock inducible and one is stationary-phase inducible. here, we demonstrate that myxococcus xanthus possesses at least five cspa homologues, cspa to cspe. hydrophobic residues forming a hydrophobic core, and aromatic residues, which are included in functional motifs rnp-1 and rnp-2 involved in binding to rna and ssdna, are well conserved. these facts suggest that m. xanthus cspa homologues have a ...	1999	10542339
conservation of the pyrrolnitrin biosynthetic gene cluster among six pyrrolnitrin-producing strains.	the prnabcd gene cluster from pseudomonas fluorescens encodes the biosynthetic pathway for pyrrolnitrin, a secondary metabolite derived from tryptophan which has strong anti-fungal activity. we used the prn genes from p. fluorescens strain bl915 as a probe to clone and sequence homologous genes from three other pseudomonas strains, burkholderia cepacia and myxococcus fulvus. with the exception of the prna gene from m. fulvus59% similar among the strains, indicating that the biochemical pathway f ...	1999	10547442
intercellular signaling during fruiting-body development of myxococcus xanthus.	the myxobacterium myxococcus xanthus has a life cycle that is dominated by social behavior. during vegetative growth, cells prey on other bacteria in large groups that have been likened to wolf packs. when faced with starvation, cells form a macroscopic fruiting body containing thousands of spores. the social systems that guide fruiting body development have been examined through the isolation of conditional developmental mutants that can be stimulated to develop in the presence of wild-type cel ...	1999	10547700
asgd, a new two-component regulator required for a-signalling and nutrient sensing during early development of myxococcus xanthus.	myxococcus xanthus has a complex life cycle that includes fruiting body formation. one of the first stages in development has been called a-signalling. the asg (a-signalling) mutants have been proposed to be deficient in producing a-signal, resulting in development arresting at an early stage. in this paper, we report the identification of a new asg locus asgd. this locus appears to be involved in both environmental sensing and intercellular signalling. expression of asgd was undetected during v ...	1999	10564471
sporulation timing in myxococcus xanthus is controlled by the espab locus.	the fruiting body development of myxococcus xanthus consists of two separate but interacting pathways: one for aggregation of many cells to form raised mounds and the other for sporulation of individual cells into myxospores. sporulation of individual cells normally occurs after mound formation, and is delayed at least 30 h after starvation under our laboratory conditions. this suggests that m. xanthus has a mechanism that monitors progress towards aggregation prior to triggering sporulation. a ...	1999	10564511
melithiazols, new beta-methoxyacrylate inhibitors of the respiratory chain isolated from myxobacteria. production, isolation, physico-chemical and biological properties.	new antibiotic compounds, melithiazols, were isolated from the culture broth of strains of the myxobacteria melittangium lichenicola, archangium gephyra, and myxococcus stipitatus. the compounds belong to the group of beta-methoxyacrylate (moa) inhibitors and are related to the myxothiazols. the melithiazols show high antifungal activity, but are less toxic than myxothiazol a and its methyl ester in a growth inhibition assay with mouse cell cultures. the melithiazols inhibit nadh oxidation by su ...	1999	10580385
genetic and functional analysis of genes required for the post-modification of the polyketide antibiotic ta of myxococcus xanthus.	the antibiotic ta of myxococcus xanthus is a complex macrocyclic polyketide, produced through successive condensations of acetate by a type i pks (polyketide synthase) mechanism. the genes encoding ta biosynthesis are clustered on a 36 kb dna fragment, which has been cloned and analysed. the chemical structure of ta and the mechanism by which it is synthesized indicate the need for several post-modification steps, which are introduced into the carbon chain of the polyketide to form the final bio ...	1999	10589713
motility in myxococcus xanthus and its role in developmental aggregation.	the frz signal transduction system of myxococcus xanthus was originally thought to be a simple variation of the well-characterized che system of the enteric bacteria. recently, however, many additional frz proteins, along with alternative signal transduction systems, have been discovered. together these signal transduction pathways coordinate cell-cell behavior, permitting the complex interactions required for developmental aggregation and fruiting body formation.	1999	10607622
effect of cellular filamentation on adventurous and social gliding motility of myxococcus xanthus.	filamentous bacterial cells often provide biological information that is not readily evident in normal-size cells. in this study, the effect of cellular filamentation on gliding motility of myxococcus xanthus, a gram-negative social bacterium, was investigated. elongation of the cell body had different effects on adventurous and social motility of m. xanthus. the rate of a-motility was insensitive to cell-body elongation whereas the rate of s-motility was reduced dramatically as the cell body go ...	1999	10611358
sequences and evolutionary analyses of eukaryotic-type protein kinases from streptomyces coelicolor a3(2).	four eukaryotic-type protein serine/threonine kinases from streptomyces coelicolor a3(2) were cloned and sequenced. to explore evolutionary relationships between these and other protein kinases, the distribution of protein serine/threonine kinase genes in prokaryotes was examined with the tfasta program. genes of this type were detected in only a few species of prokaryotes and their distribution was uneven; streptomyces, mycobacterium, synechocystis and myxococcus each contained more than three ...	1999	10627033
the myxococcus xanthus pilq (sgla) gene encodes a secretin homolog required for type iv pilus biogenesis, social motility, and development.	the myxococcus xanthus sgla1 spontaneous mutation was originally isolated because it allowed dispersed cell growth in liquid yet retained the ability to form fruiting bodies. consequently, most of today's laboratory strains either contain the sgla1 mutation or were derived from strains that carry it. subsequent work showed that sgla was a gene for social gliding motility, a process which is mediated by type iv pili. here sgla is shown to map to the major pil cluster and to encode a 901-amino-aci ...	1999	9864308
a nusg-like transcription anti-terminator is involved in the biosynthesis of the polyketide antibiotic ta of myxococcus xanthus.	the antibiotic ta of myxococcus xanthus is synthesized through a type i polyketide synthase mechanism. previous studies have indicated that several genes essential for ta production are clustered within a 40-kb region and are transcriptionally co-regulated. in this study, we report the genetic analysis of the first gene in the ta gene cluster, identified as a nusg-like transcription anti-terminator. functional analysis of this nusg-like anti-terminator gene by specific gene disruption confirms t ...	1999	9919671
the first gene in the biosynthesis of the polyketide antibiotic ta of myxococcus xanthus codes for a unique pks module coupled to a peptide synthetase.	the polyketide antibiotic ta is synthesized by the gram negative bacterium myxococcus xanthus in a multi-step process in which a unique glycine-derived molecule is used as a starter unit and elongated through the condensation of 11 acetate molecules by polyketide synthases (pkss). analysis of a 7.2 kb dna fragment, encoding the protein that carries out the first condensation step, revealed that the fragment constitutes a single open reading frame, referred to as ta1, which lacks the 5' and 3' en ...	1999	9973564
a new set of chemotaxis homologues is essential for myxococcus xanthus social motility.	myxococcus xanthus cells aggregate and develop into multicellular fruiting bodies in response to starvation. a new m. xanthus locus, designated diffor defective in fruiting, was identified by the characterization of a mutant defective in fruiting body formation. molecular cloning, dna sequencing and sequence analysis indicate that the dif locus encodes a new set of chemotaxis homologues of the bacterial chemotaxis proteins mcps (methyl-accepting chemotaxis proteins), chew, chey and chea. the dif ...	1998	9988486
myxococcus xanthus biomass as biosorbent for lead.	this paper deals with lead biosorption by myxococcus xanthus biomass in which dry biomass, accumulating up to 1.28 mmol of lead g(-1), is demonstrated to be a more efficient biosorbent than wet biomass. dry biomass biosorption was found to be very rapid, reaching equilibrium after 5-10 min. culture age, the initial lead concentration and ph affected this process, but temperature did not. furthermore, by using sodium citrate as a desorbent agent, 92.17% of the biosorbed lead could be recovered. i ...	1998	15244058
the anti-sigma factors.	a mechanism for regulating gene expression at the level of transcription utilizes an antagonist of the sigma transcription factor known as the anti-sigma (anti-sigma) factor. the cytoplasmic class of anti-sigma factors has been well characterized. the class includes asia form bacteriophage t4, which inhibits escherichia coli sigma 70; flgm, present in both gram-positive and gram-negative bacteria, which inhibits the flagella sigma factor sigma 28; spoiiab, which inhibits the sporulation-specific ...	1998	9891799
cooperative organization of bacterial colonies: from genotype to morphotype.	in nature, bacteria must often cope with difficult environmental conditions. to do so they have developed sophisticated cooperative behavior and intricate communication pathways. utilizing these elements, motile microbial colonies frequently develop complex patterns in response to adverse growth conditions on hard surfaces under conditions of energy limitation. we employ the term morphotype to refer to specific properties of colonial development. the morphologies we discuss include a tip-splitti ...	1998	9891813
myxococcus xanthus displays frz-dependent chemokinetic behavior during vegetative swarming.	myxococcus xanthus has been shown to utilize both directed (tactic) and undirected (kinetic) movements during different stages of its complex life cycle. we have used time-lapse video microscopic analysis to separate tactic and kinetic behaviors associated specifically with vegetatively swarming cells. isolated individual cells separated by a thin agar barrier from mature swarms showed significant increases in gliding velocity compared to that of similar cells some distance from the swarm. this ...	1998	9440539