| population structure in a critically endangered arctic fox population: does genetics matter? | the arctic fox (alopex lagopus) in scandinavia is classified as critically endangered after having gone through a severe decline in population size in the beginning of the 20th century, from which it has failed to recover despite more than 65 years of protection. arctic foxes have a high dispersal rate and often disperse over long distances, suggesting that there was probably little population differentiation within scandinavia prior to the bottleneck. it is, however, possible that the recent de ... | 2006 | 16911202 |
| physiological adaptations to fasting in an actively wintering canid, the arctic blue fox (alopex lagopus). | this study investigated the physiological adaptations to fasting using the farmed blue fox (alopex lagopus) as a model for the endangered wild arctic fox. sixteen blue foxes were fed throughout the winter and 32 blue foxes were fasted for 22 d in nov-dec 2002. half of the fasted blue foxes were food-deprived again for 22 d in jan-feb 2003. the farmed blue fox lost weight at a slower rate (0.97-1.02% body mass d(-1)) than observed previously in the arctic fox, possibly due to its higher initial b ... | 2006 | 16358268 |
| comparative aspects of sperm membrane fatty acid composition in silver (vulpes vulpes) and blue (alopex lagopus) foxes, and their relationship to cell cryopreservation. | cryogenic protocols have been developed for the storage of farmed silver fox (vulpes vulpes) spermatozoa. however, these same protocols and modifications of these protocols have failed to satisfactorily preserve spermatozoa collected from farmed blue foxes (alopex lagopus). because cryogenic success has been linked to membrane composition, the plasma membrane lipid composition of farmed blue fox and silver fox spermatozoa was studied. silver fox spermatozoal membranes have significantly higher l ... | 2005 | 16040024 |
| two cysteine substitutions in the mc1r generate the blue variant of the arctic fox (alopex lagopus) and prevent expression of the white winter coat. | we have characterized two mutations in the mc1r gene of the blue variant of the arctic fox (alopex lagopus) that both incorporate a novel cysteine residue into the receptor. a family study in farmed arctic foxes verified that the dominant expression of the blue color phenotype cosegregates completely with the allele harboring these two mutations. additionally to the altered pigment synthesis, the blue fox allele suppresses the seasonal change in coat color found in the native arctic fox. consequ ... | 2005 | 15982782 |
| non-invasive faecal steroid monitoring of ovarian and adrenal activity in farmed blue fox (alopex lagopus) females during late pregnancy, parturition and lactation onset. | in the semi-domesticated blue fox, handling stress may influence reproductive performance and increase perinatal pup loss. ovarian and adrenal steroids were analysed in faecal samples collected from mid-gestation through the first week of lactation in 40 female blue foxes to characterize hormone patterns during this important reproductive period. daily faecal samples were collected from 40 foxes during 30 pregnancies, one late abortion and nine bred-matched non-pregnancies. mean concentrations o ... | 2005 | 15911180 |
| ileal and total tract nutrient digestibility in blue foxes (alopex lagopus) fed extruded diets containing different protein sources. | this study compared apparent ileal and total tract digestibility of macronutrients and amino acids in blue foxes (alopex lagopus) fed dry extruded diets. the control diet contained fish meal as the main protein source, while in the other diets 50% of the fish meal protein was replaced by not de-hulled solvent-extracted soybean meal, meat meal or bacterial protein meal. ileal digestibility was obtained with animals modified with ileorectal anastomosis (ira method). there were no significant diffe ... | 2005 | 15889653 |
| [effect of the hereditary characteristics of male blue foxes alopex lagopus l. on the sex ratio of their offspring]. | family analysis of a commercial population of the blue fox (the pushkinskoe breeding fur farm, moscow oblast) with respect to secondary sex ratio has been performed. the offspring of each individual male or female involved in crossing between 1984 and 1988 was analyzed. the study of all families formed by every male and every female has made it possible to determine a group of "outstanding" fathers (23 out of 287 males), whose offspring was predominantly male (62.1% of the offspring were males, ... | 2005 | 15865299 |
| introduced predators transform subarctic islands from grassland to tundra. | top predators often have powerful direct effects on prey populations, but whether these direct effects propagate to the base of terrestrial food webs is debated. there are few examples of trophic cascades strong enough to alter the abundance and composition of entire plant communities. we show that the introduction of arctic foxes (alopex lagopus) to the aleutian archipelago induced strong shifts in plant productivity and community structure via a previously unknown pathway. by preying on seabir ... | 2005 | 15790855 |
| adiponectin and peptide yy in the fasting blue fox (alopex lagopus). | adiponectin (acrp30) and peptide yy (pyy) are weight-regulatory hormones participating in the control of energy homeostasis. this study investigated the effects of long-term wintertime fasting on plasma acrp30 and pyy levels in the carnivorous blue fox, a farm-bred variant of the arctic fox (alopex lagopus). plasma acrp30 and pyy concentrations were determined with radioimmunoassays during a 22-day period of fasting, which led to a 20.3% reduction in body mass of the animals (n=32). sixteen fed ... | 2005 | 15748866 |
| circannual leptin and ghrelin levels of the blue fox (alopex lagopus) in reference to seasonal rhythms of body mass, adiposity, and food intake. | the aim of the study was to investigate the circannual rhythms of leptin and ghrelin in the blue fox, a variant of the endangered arctic fox, in relation to its seasonal cycles of body mass, adiposity and food intake. the effects of long-term fasting and exogenous melatonin treatment on these weight-regulatory hormones were also investigated. the leptin concentrations of the blue fox increased during the autumnal accumulation of fat and decreased during the wintertime and vernal weight loss peri ... | 2005 | 15612002 |
| effects of fasting and exogenous melatonin on annual rhythms in the blue fox (alopex lagopus). | the arctic fox (alopex lagopus) is a winter-active inhabitant of the high arctic with extreme fluctuations in photoperiod and food availability. the blue fox is a semi-domesticated variant of the wild arctic fox reared for the fur industry. in this study, 48 blue foxes were followed for a year in order to determine the effects of exogenous melatonin and wintertime food deprivation on their reproductive and thyroid axes. half of the animals were treated with continuous-release melatonin capsules ... | 2004 | 15528167 |
| effects of season, food deprivation and re-feeding on leptin, ghrelin and growth hormone in arctic foxes (alopex lagopus) on svalbard, norway. | the arctic fox (alopex lagopus) is a medium-sized predator of the high arctic experiencing extreme seasonal fluctuations in food availability, photoperiod and temperature. in this study, the plasma leptin, ghrelin and growth hormone (gh) concentrations of male arctic foxes were determined during a food deprivation period of 13 days and the subsequent recovery in november and may. leptin, ghrelin and gh were present in arctic fox plasma in amounts comparable to other carnivores. the plasma leptin ... | 2004 | 14639485 |
| [thyroid hormones and activity of lysosomal proteolytic enzymes in organs of arctic fox alopex lagopus]. | | 2013 | 12973906 |
| handling during pregnancy in the blue fox (alopex lagopus): the influence on the fetal gonadal function. | in previous studies it has been shown that handling produced stress in pregnant blue fox vixens increasing plasma level and adrenal in vitro production of cortisol. moreover, this treatment increased plasma cortisol levels in the fetuses. the present study was designed to examine effects of a 1-min daily handling stress applied to pregnant blue fox vixens on fetal gonadal steroidogenesis. plasma concentrations of oestradiol and testosterone, gonadal content and gonadal in vitro production of the ... | 2003 | 12812765 |
| surgical implantation of radio transmitters in arctic foxes (alopex lagopus) on svalbard, norway. | twelve captive wild-caught adult arctic foxes (alopex lagopus) were anesthetized a total of 24 times for an equal number of surgical procedures involving implantation of heart rate (hr) and core body temperature transmitters (tb) between october 1995 and april 1997. xylazine-ketamine and medetomidine-ketamine anesthesia was used, resulting in an unacceptably high death rate. one out of four foxes anesthetized with xylazine-ketamine died, whereas two of nine foxes anesthetized with medetomidine-k ... | 2002 | 12564532 |
| influence of dietary protein level and the amino acids methionine and lysine on leather properties of blue fox (alopex lagopus) pelts. | the influence of dietary protein, methionine, and lysine on leather quality in blue fox pelts was studied. the pelt material originated from animals in two consecutive feeding trials (exp. 1 and exp. 2) with three protein levels: conventional, slightly lowered, and very low. the two lowest protein diets were fed as such or as supplemented with methionine or with lysine (lysine only in exp. 2). the following physical leather properties were measured: breaking load (brl), tensile strength (ten), r ... | 2002 | 12553694 |
| comparative nutrient digestibility of arctic foxes (alopex lagopus) on svalbard and farm-raised blue foxes (alopex lagopus). | arctic foxes from svalbard (n=4) and farmed blue foxes (n=4) was used in a digestibility experiment with a high-carbohydrate feed to add more information to the nutritional physiology of the arctic fox, and to compare its digestive capacity with that of the farmed blue fox. the arctic fox has a diet containing mainly protein and fat from mammals and birds, while farmed blue foxes have been exposed to an omnivorous dietary regime for more than 80 generations. the experiment showed in general no d ... | 2003 | 12507608 |
| [a variation of secondary sex ratio in blue fox (alopex lagopus l.)]. | the effects of several genotypic and paratypic factors on the secondary (at birth) sex ratio was analyzed in blue fox bred in captivity. in particular, variation of sex ratio was for the first time studied as dependent on sire's age (without considering dam's age), the ages of both sire and dam, and the lines of both parents. the initial data were obtained from the pushkino breeding facility, moscow oblast. in total, 15,396 puppies were analyzed. the frequency of males (p) in this population was ... | 2002 | 12449653 |
| temporal variability in arctic fox diet as reflected in stable-carbon isotopes; the importance of sea ice. | consumption of marine foods by terrestrial predators can lead to increased predator densities, potentially impacting their terrestrial resources. for arctic foxes (alopex lagopus), access to such marine foods in winter depends on sea ice, which is threatened by global climate change. to quantify the importance of marine foods (seal carrion and seal pups) and document temporal variation in arctic fox diet i measured the ratios of the stable isotopes of carbon ((13)c/(12)c) in hair of arctic foxes ... | 2002 | 24599371 |
| exclusion by interference competition? the relationship between red and arctic foxes. | the distribution of many predators may be limited by interactions with larger predator species. the arctic fox in mainland europe is endangered, while the red fox is increasing its range in the north. it has been suggested that the southern distribution limit of the arctic fox is determined by interspecific competition with the red fox. this has been criticised, on the basis that the species co-exist on a regional scale. however, if the larger red fox is superior and interspecific competition im ... | 2002 | 28547354 |
| comparison between microscopic and automated differential leukocyte counts in the silver fox (vulpes vulpes) and the blue fox (alopex lagopus). | differential leukocyte (wbc) counts in blood from clinically healthy silver foxes (n=32) and blue foxes (n=37) obtained from an automated hematology analyzer (technicon h*1 hematology system) with canine software were compared with microscopic differential wbc counts (m-diff). there was good agreement between the automated differential cell count (a-diff) and the m-diff for neutrophil and lymphocyte percentages. the correlation was lower for monocyte percentages and variable for eosinophil perce ... | 1999 | 12075528 |
| substrate oxidation in male blue foxes (alopex lagopus) during feeding, fasting and realimentation. | | 2002 | 12042531 |
| maturation and fertilization of blue fox (alopex lagopus) oocytes in vitro. | the aim of the present study was to assess the progression of meiotic maturation and fertilization of in vitro matured blue fox (alopex lagopus) oocytes at different time intervals after in vitro maturation and insemination by the use of confocal laser scanning microscopy. a total of 242 immature oocytes from ovarian follicles 1-2 mm in diameter from seven ovulating blue fox vixens at oestrus were cultured for 48 h in tcm-199 before in vitro insemination with 5.0 x 10(5) frozen-thawed fox sperma ... | 2001 | 11787145 |
| handling during pregnancy in the blue fox (alopex lagopus): the influence on the fetal pituitary-adrenal axis. | previous studies revealed that handling is a stressor for farmed blue foxes. the present study was designed to examine the effects of a 1-min daily handling stress applied to pregnant blue fox vixens on the function of the fetal pituitary-adrenal system. plasma concentrations of adrenocorticotropin hormone (acth), cortisol, and progesterone, adrenal content of cortisol and progesterone, in vitro adrenal production of these steroids and response to acth, and adrenal weights were measured in contr ... | 2001 | 11551111 |
| alterations of the pituitary-gonadal axis in the neonatal blue fox (alopex lagopus) exposed to prenatal handling stress. | handling is a stressor for blue foxes. the influence of preterm handling (1 min daily) of vixens was investigated in 68, 10-day-old cubs, 34 male and 34 female. body, gonadal and pituitary weight, ano-genital distance, gonadal testosterone and oestradiol content and in vitro production, and pituitary lh content were measured in all cubs. the gonads were frozen or incubated in vitro with, or without, added hcg (2.5 iu per sample). the gonadal incubates and homogenates were analysed for testostero ... | 2000 | 11302420 |
| milk intake in blue fox (alopex lagopus) and silver fox (vulpes vulpes) cubs in the early suckling period. | milk intake of fox cubs (2-16 days of age; body weight, 96-649 g) in ten blue fox litters and ten silver fox litters were measured by the water isotope dilution (wid) technique following a single intraperitoneal injection of tritiated water (3hho). litter size varied from four to 14 in blue foxes and from three to eight in silver foxes. silver fox cubs had higher birth weights than blue foxes. inter-species body weights and growth rates were apparently dependent on litter size and the dam's cons ... | 2000 | 11064289 |
| field anesthesia of wild arctic fox (alopex lagopus) cubs in the swedish lapland using medetomidine-ketamine-atipamezole. | a safe and effective anesthetic regime for use in arctic fox (alopex lagopus) cubs was developed. during july 1996, six free-ranging 6-8-wk-old cubs were captured near their den in vindelfjallen nature reserve, sweden. medetomidine and ketamine hci, followed by atipamezole, were selected for the anesthetic trial because of the well-documented safety and efficacy of this drug combination in a broad range of species. the dosage regimen used was 50 microg/kg medetomidine combined with 2.5 mg/kg ket ... | 2000 | 10982142 |
| hormones and metabolites of arctic foxes (alopex lagopus) in response to season, starvation and re-feeding. | svalbard's arctic foxes experience large seasonal variations in light, temperature and food supply throughout the year, which may result in periods of starvation. the aim of this work is to investigate if there are seasonal variations in post-absorptive plasma thyroid hormones (free thyroxin (ft(4)), free triiodothyronine (ft(3)) and reverse triiodothyronine (rt(3))) and metabolites (free fatty-acids (ffa) and beta-hydroxybutyrate (beta-ohb)) with season and their response to starvation and re-f ... | 2000 | 10936768 |
| preference for various nest box designs in farmed silver foxes (vulpes vulpes) and blue foxes (alopex lagopus). | nest box choice experiments were carried out outside the breeding season on adult silver and blue fox vixens with no previous permanent nest box experience. nest boxes were varied in height of placement, number of rooms, presence of entrance room or platform and light conditions. only one parameter was varied in any one experiment. both fox species clearly preferred an elevated multi-room nest box; while silver foxes showed preference for boxes supplied with a platform, blue foxes preferred boxe ... | 2000 | 10719195 |
| seasonal trends in body mass, food intake and resting metabolic rate, and induction of metabolic depression in arctic foxes (alopex lagopus) at svalbard. | post-absorptive resting metabolic rates (rmrs), body mass and ad libitum food intake were recorded on an annual cycle in captive arctic foxes (alopex lagopus) at svalbard. during the light season in may and in the dark period in november, rmr during starvation and subsequent re-feeding were also measured. in contrast to earlier findings, the present study indicated a seasonal trend in post-absorptive rmr (in w.kg-1 and w.kg-0.75). the values in the light summer were 15% and 11% higher than the v ... | 1999 | 10549138 |
| relationship between hyponeophagia and adrenal cortex function in farmed foxes. | the adrenal cortex function of farmed blue (alopex lagopus) and silver foxes (vulpes vulpes) differing in their reaction in the feeding test were assessed. the urine cortisol:creatinine ratio was lower for those animals eating in the feeding test in comparison to those not eating in both species. in addition, eater silver foxes had lower baseline serum cortisol concentration and also lower serum cortisol concentration 2 h after acth administration than noneaters. there were no differences in any ... | 2013 | 10073480 |
| stable isotopes in adipose tissue fatty acids as indicators of diet in arctic foxes (alopex lagopus). | | 1997 | 9483672 |
| dietary variation in arctic foxes (alopex lagopus)-an analysis of stable carbon isotopes. | we used stable carbon isotopes to analyse individual variation in arctic fox diet. we extracted collagen from bones (the lower jaw), and measured stable carbon isotopes. the foxes came from three different localities: iceland, where both microtines and reindeer are rare; west greenland, where microtines are absent; and sweden, where scat analyses showed the primary food to be microtine rodents and reindeer. the icelandic samples included foxes from both coastal and inland habitats, the swedish s ... | 1994 | 28313876 |
| fertilization and early embryonic development in the blue fox (alopex lagopus). | a total of 15 blue fox vixens aged 1-6 years were mated, 12 once on the first day of estrus and three a second time 48 hr after the first mating, and were killed 4 hr to 8 days following mating. ova were collected from the oviducts, evaluated by stereomicroscopy, and studied by transmission (tem; n = 49, 12 vixens) or scanning (sem, n = 11, three vixens) electron microscopy. at 0-3 days after ovulation, the ova had not cleaved and were at different stages of meiotic maturation. in about one-half ... | 1993 | 8286115 |
| genetic subdivisions among small canids: mitochondrial dna differentiation of swift, kit, and arctic foxes. | gene flow can effectively suppress genetic divergence among widely separated populations in highly mobile species. however, the same may not be true of species that typically disperse over shorter distances. using mtdna restriction-site and sequence analyses, we evaluate the extent of divergence among populations of two small relatively sedentary north american canids, the kit and swift foxes (genus vulpes). we determine the significance of genetic differentiation among populations separated by ... | 1993 | 28564903 |
| [analysis of the selection process in breeding of caging populations of arctic fox (alopex lagopus l.)]. | the purpose of this research is analysis of supporting heterozygosity mechanisms in caging population of polar fox (alopex lagopus l.). the polymorphism of the gene, which code the blood serum protein-transferrin, was used as a genetic marker. the level of the heterozygosity was studied in the reproductive and young parts of population. as it turned out, the reproductive part is separated on some subpopulations, moreover, inbreeding lead to the decrease of heterozygosity level in this part of po ... | 1993 | 8307365 |
| pulmonary emphysema in an arctic fox. | | 1993 | 8236654 |
| agonistic behaviour and dominance relations of captive arctic foxes (alopex lagopus) in svalbard. | agonistic behaviour and dominance relations were studied in three groups of arctic foxes (alopex lagopus) on the western coast of svalbard (79°n): (1) five 'tame' foxes (3♂♂, 2♀♀) kept in captivity for 9-26 months, (2) twenty-two 'wild' foxes (11♂♂, 11♀♀) kept in captivity for 4 days to 3 weeks, and (3) free-living foxes. experiments were started by introducing two foxes (n = 74 dyads) into a large enclosure (360 m(2)), scoring winners and losers in a competition for food, calculating a dominanc ... | 1993 | 24895938 |
| relationship between gonadotrophins, inhibin and sex steroid secretion during the periovulatory period and the luteal phase in the blue fox (alopex lagopus). | the blue fox is a monestrous seasonal breeder with a pro-oestrus and oestrus lasting several days and a prolonged luteal phase in non-pregnant as well as pregnant vixens. ovulation occurs 2 days after the preovulatory luteinizing hormone (lh) peak at the onset of oestrus; oocytes are ovulated as primary oocytes and maturation is completed 2-3 days later. fertilization is possible during all stages of oocyte maturation until degeneration of oocytes 5 or 6 days after the lh peak. in this study, ch ... | 1993 | 8229964 |
| fertilization in vitro of oocytes matured in vivo in the blue fox (alopex lagopus). | six unmated blue fox vixens were killed 2-3 days after peak vaginal electrical resistance. measurements of luteinizing hormone (lh) showed that this corresponded to a time period of 6-10 days after the preovulatory lh peak in these vixens. a total of 63 ova were collected from the oviducts of the vixens, and 45 of the ova were used for study of fertilization in vitro. the ova were placed in 50 microliter droplets of fertilization medium and inseminated with 15,000-45,000 frozen-thawed silver fox ... | 1993 | 8229929 |
| rapid detection of the preovulatory luteinizing hormone peak in the blue fox (alopex lagopus) by an enzyme-linked immunosorbent assay. | an enzyme-linked immunosorbent assay (elisa) developed for the rapid measurement of luteinizing hormone (lh) in blood of many mammalian species has been validated in the fox. for this purpose, daily plasma samples collected from six vixens during the periovulatory period were assayed for lh using elisa. the results were compared with those obtained by radioimmunoassay (ria), and related to parameters used to determine the time of ovulation (onset of oestrus, vaginal electrical resistance peak) a ... | 1993 | 8229918 |
| the optimum time for single artificial insemination of blue fox vixens (alopex lagopus) with frozen-thawed semen from silver foxes (vulpes vulpes). | during the breeding season of 1991 a total of 608 blue fox vixens aged 1 to 6 years (2.3 +/- 0.1 years, mean +/- sem) from 2 farms were artificially inseminated intrauterine once with frozen-thawed silver fox semen (1 ml dose containing a total of 150 million spermatozoa). the vixens were allocated to 3 different groups according to the time of insemination. vixens in group 1 (n = 203), group 2 (n = 198), and group 3 (n = 207) were inseminated on the first, second or third day after the peak val ... | 1992 | 16727185 |
| studies on abnormal moulting in the farm-raised blue fox (alopex lagopus). | in a farm-raised, adult female blue fox (alopex lagopus) it was observed that apparently the winter coat was shed abnormally. furthermore, the individual was never recorded as being on heat. comparative histological and clinical-chemical examinations showed that the winter coat cycle was postponed approximately 6 months, and that the hair growth therefore took place in the spring. at first a kind of biological summer coat was produced, and then a biological mature winter coat. this was compared ... | 1992 | 1455916 |
| metabolic rate and evaporative water loss at different ambient temperatures in two species of fox: the red fox (vulpes vulpes) and the arctic fox (alopex lagopus). | 1. resting metabolic rate (rmr) and evaporative water loss (ewl) of adult red and arctic foxes were determined over ambient temperature (ta) ranges of -13-37 degrees c and -5-30 degrees c as oxygen consumption and amount of water in expired air using an open flow system. 2. the average rmr was 2.60 +/- 0.14 w/kg for the winter red fox, 2.59 +/- 0.14 w/kg for the summer red fox, and 2.35 +/- 0.11 w/kg for the winter arctic fox. 3. the rate of increase of rmr was significant (p less than 0.05) onl ... | 1992 | 1351445 |
| the effect of sperm number on fertility in blue fox vixens (alopex lagopus ) artificially inseminated with frozen silver fox (vulpes vulpes ) semen. | during the breeding seasons of 1989 and 1990, a total of 617 blue fox vixens aged 1 to 6 years (mean +/- sem, 2.6 +/- 0.1) were inseminated with frozen silver fox semen with either 150 million (n = 213, 1989 + 1990), 100 million (n=172, 1990), 75 million (n = 119, 1989) or 37.5 million (n = 113, 1989) spermatozoa per insemination. two intrauterine inseminations, each with an insemination volume of 1.0 ml, were performed at 24-hour intervals on the first and second days after maximum vaginal elec ... | 1992 | 16727071 |
| species- and tissue-specific transcription of complex, highly repeated satellite-like bsp elements in the fox genome. | we have studied the transcription of highly repeated satellite-like bsp elements containing the potential promoter boxes for rna polymerase iii in the genomes of adult silver and arctic foxes. the bsp repeat transcripts were abundant enough to be detected by northern blot and semiquantitative dot blot hybridizations, and the majority were found in the nuclear rna fraction from arctic fox kidneys. weak hybridization signals were revealed with the cytoplasmic rna preparation from silver fox kidney ... | 1992 | 1377064 |
| early experience with the farm environment and effects on later behaviour in silver vulpes vulpes and blue foxes alopex lagopus. | seventy-one silver fox and 141 blue fox cubs were exposed to constant visual contact with the farm environment from the age of 2 to 8 weeks. the exposure consisted in opening a door in the nest box facing the feed gang-way. control cubs (33 silver and 77 blue foxes) were reared in similar but closed nest boxes. all cubs were tested at the age of 12-16 weeks and again at the age of 23-28 weeks; during these tests the behavioural responses of the foxes towards a human being were recorded. both tes ... | 1991 | 24923975 |
| [detection of estrus and determination of the optimal time for insemination in polar foxes (alopex lagopus)]. | oestrus cycles were investigated in seven polar foxes: the investigation consisted of evaluation of clinical symptoms of heat (vulva enlargement), measurement of vaginal mucus electrical resistance and determination of progesterone concentrations in the blood plasma of foxes; the objective was to determine optimum insemination time. the females were inseminated with fresh semen intravaginally by means of a pseudopenis, a day following the record of maximum electrical resistance of vaginal mucus ... | 1991 | 1807032 |
| genetic polymorphism of adenosine deaminase and mannose phosphate isomerase in blood of arctic foxes, alopex lagopus. | blood samples of 70 foxes, including 10 families, have been investigated by horizontal starch gel electrophoresis for the enzymes adenosine deaminase (ada) and mannose phosphate isomerase (mpi). the observed variation of the enzymes could be explained as a result of one locus with two codominant alleles and one with three respectively. the segregation in the families of the alleles assumed for the two loci is in accordance with this genetic model. the frequency of the two alleles at the ada locu ... | 1991 | 2024784 |
| centric-fusion translocation and whole-arm heterochromatin in the karyotype of the blue fox (alopex lagopus l.): synaptonemal complex analysis. | conventional observations of mitotic chromosomes from two male blue foxes, revealing a centric-fusion translocation and whole-arm heterochromatin, were verified by synaptonemal complex analysis. this analysis revealed that the centric fusion had been preceded by a conspicuous loss of chromosome material in the two one-armed chromosomes involved, but the chromosomal origin of the centric-fusion kinetochore could not be established. the nontranslocated chromosomes of the trivalent, which in all ce ... | 1991 | 1855385 |
| the spermatogenic cycle in the blue fox (alopex lagopus): relative frequency and absolute duration of the different stages. | the spermatogenic cycle of the blue fox was divided into eight distinct stages, based on an analysis of different cell associations of the seminiferous epithelium. the criteria used for classification of the stages were the type of spermatogonia, the occurrence of meiotic figures, and the shape and location of spermatids. the relative frequencies of the stages i to viii were 25.7, 9.8, 8.7, 5.9, 13.8, 9.9, 10.6 and 15.5%, respectively. the duration of one cycle of the seminiferous epithelium was ... | 1990 | 2387650 |
| adenine nucleotides, serotonin, and aggregation properties of platelets of blue foxes (alopex lagopus) with the chediak-higashi syndrome. | bleeding times, concentrations of serotonin in whole blood, and concentrations of adenine nucleotides as well as aggregation properties of platelets were examined in 18 blue foxes with chediak-higashi-like syndrome (chs) and 16 controls. a claw of each ketamine-sedated fox was cut until bleeding started and the bleeding time was recorded as the time from the first to the last drop. the bleeding time was greatly increased in chs foxes. platelet counts of chs foxes were normal, but aggregation ind ... | 1990 | 2309785 |
| structural aspects of oocyte maturation in the blue fox (alopex lagopus). | blood samples were taken weekly from seventeen mature blue fox vixens (average age five years), from late anoestrus until pro-oestrus, and then taken daily. the vixens were sacrificed at various stages of oestrus, and oocytes were collected from ovarian follicles by aspiration, and/or from oviducts by flushing. the structural features of oocyte maturation were related to the time of the luteinizing hormone (lh) peak. on days 1-2 after the lh peak the oocyte nucleus migrated from a central to a p ... | 1990 | 2346225 |
| medetomidine- and medetomidine-ketamine-induced immobilization in blue foxes (alopex lagopus) and its reversal by atipamezole. | the sedative and immobilizing effects of the alpha 2-adrenoceptor agonist medetomidine alone or combined with the dissociative anesthetic ketamine, were studied in blue foxes. medetomidine at doses of 25 and 50 micrograms/kg induced moderate to deep sedation, but only with the highest medetomidine dose tested, 100 micrograms/kg, was the immobilization complete. medetomidine 50 micrograms/kg combined with ketamine 2.5 mg/kg rapidly induced complete immobilization, characterized by good myorelaxat ... | 1990 | 1975971 |
| induction of copulatory behavior in castrated female and male arctic foxes. | the aim of the study was to test if it is possible to induce complete copulatory behavior in castrated arctic foxes (alopex lagopus) of both sexes for the purpose of other experiments. two groups of castrated, sexually experienced arctic foxes, four pairs in experiment 1 (a pilot study) and eight pairs in experiment 2, were treated with different regimes of hormone (estrogens and progesterone in females, testosterone in males). the animals were than tested for copulatory behavior. nine out of 12 ... | 1988 | 3235063 |
| glucose turnover and defense of blood glucose levels in arctic fox (alopex lagopus). | 1. glucose utilization was assessed in fed and fasted arctic fox, maintained on a diet similar in composition to food available in the wild. 2. fasted (24 hr) glucose concentration was not significantly different from the fed level (134 mg/dl). 3. fasting was associated with a significant reduction in glucose space, pool size, total entry rate, and irreversible loss which suggests a decline in gluconeogenesis. 4. glucose recycling was not significantly different between the fed and fasted states ... | 1988 | 2906832 |
| cholinesterase activities in uterus of normal and fenchlorphos treated blue foxes (alopex lagopus) during various reproductive states. | | 1988 | 2462338 |
| preliminary studies of the effects of bromocriptine on testicular regression and the spring moult in a seasonal breeder, the male blue fox (alopex lagopus). | bromocriptine administration in the form of slow-release injections to male blue foxes during march-may abolished the normal spring rise in plasma prolactin concentrations seen in may and june. the spring moult was prevented and the treated animals retained a winter coat of varied quality and maturity until the end of the study in august. plasma testosterone concentrations fell normally from march until august. testicular regression was, however, delayed, although there were individual variation ... | 1987 | 3430468 |
| sexual development in the immature male blue fox (alopex lagopus), investigated by testicular histology, dna flow cytometry and measurement of plasma fsh, lh, testosterone and soluble testicular mn2+-dependent adenylate cyclase activity. | testicular weight in young male blue foxes increased steadily from 12 weeks of age (0.4-0.7 g) to reach peak values at the time of the mating season in march-april (5.2-6.6 g), before declining rapidly during may to low values in august at 63 weeks of age (1.3-1.6 g). primary spermatocytes were found in the spermatogenic epithelium at 20 weeks of age and by late december (29 weeks of age) elongated spermatids were seen. there was a good correlation between the seasonal variations in the presence ... | 1987 | 3123658 |
| plasma marking of arctic foxes with iophenoxic acid. | six arctic foxes (alopex lagopus) were marked with iophenoxic acid (ia), a substance which elevates concentrations of protein-bound iodine in blood plasma. buccal absorption of ia was determined by placing 20 mg ia dissolved in 100% ethyl alcohol on the tongue. blood samples collected from 1 to 36 wk following exposure showed that all foxes were marked already at 1 wk and continued until 13 wk; two foxes were still marked at 36 wk. clearance rates for iodine varied with initial dose response, an ... | 1987 | 3682104 |
| [various aspects of genetics of mutation changes in the fur color of the blue fox (alopex lagopus)]. | | 1987 | 3623096 |
| effects of melatonin implantation on spermatogenesis, the moulting cycle and plasma concentrations of melatonin, lh, prolactin and testosterone in the male blue fox (alopex lagopus). | melatonin administration to male blue foxes from august for 1 year resulted in profound changes in the testicular and furring cycles. the control animals underwent 5-fold seasonal changes in testicular volume, with maximal values in march and lowest volumes in august. in contrast, melatonin treatment allowed normal redevelopment of the testes and growth of the winter coat during the autumn but prevented testicular regression and the moult to a summer coat the following spring. at castration in a ... | 1987 | 3572874 |
| a case of granulosa cell tumour with cystic endometrial hyperplasia in a blue fox vixen (alopex lagopus). | the clinical features of a case of granulosa cell tumour in the blue fox (alopex lagopus) are described. the associated hormonal changes are discussed in relation to present knowledge of the regulation of the oestrous and furring cycles in this species. | 2006 | 3725584 |
| seasonal changes in testicular structure and function in the blue fox (alopex lagopus), as quantified by morphometric analysis and measurement of adenylate cyclase activity. | the volume of the blue fox testis showed 5-fold changes during the year, associated with considerable changes in cellular composition. the seminiferous epithelium was maximally regressed in august, when 94% of tubules contained only spermatogonia. by late october, approximately 6 months before the mating season, 40% of tubules contained primary spermatocytes. from the middle of january until the end of april all tubules contained spermatids or more advanced haploid cells. tubular diameter increa ... | 1986 | 3744586 |
| seasonal variations of lh, prolactin, androstenedione, testosterone and testicular fsh binding in the male blue fox (alopex lagopus). | the seasonal changes in testicular weight in the blue fox were associated with considerable variations in plasma concentrations of lh, prolactin, androstenedione and testosterone and in fsh-binding capacity of the testis. an increase in lh secretion and a 5-fold increase in fsh-binding capacity were observed during december and january, as testis weight increased rapidly. lh levels fell during march when testicular weight was maximal. plasma androgen concentrations reached their peak values in t ... | 1985 | 3930711 |
| the standard karyotype of the blue fox (alopex lagopus l.). committee for the standard karyotype of alopex lagopus l. | | 1985 | 4055412 |
| seasonal changes in spermatogenesis in the blue fox (alopex lagopus), quantified by dna flow cytometry and measurement of soluble mn2+ -dependent adenylate cyclase activity. | the testes of the blue fox (alopex lagopus) showed marked seasonal variations in size. testicular weight and volume increased rapidly during january and february to reach maximal values by the beginning of the breeding season (approximately 15 march). during may and june the weights and volumes of the testes declined gradually to the quiescent state which lasted from july until october. quantitation by dna flow cytometry of the seasonal changes in the relative numbers of haploid (1c), diploid (2 ... | 1984 | 6512769 |
| temporal relationships between hormonal concentrations and the electrical resistance of the vaginal tract of blue foxes (alopex lagopus) at pro-oestrus and oestrus. | during pro-oestrus, baseline lh concentrations for 9 vixens (pooled data) ranged from 0.8 to 5.3 ng/ml. in each vixen, baseline levels were interrupted by elevations of lh ranging from 3.1 to 10.4 ng/ml. a major preovulatory lh surge was detected in all the vixens. the lh peak ranged from 13.5 to 73.0 ng/ml with an average of 27.8 +/- 18.8 (s.d.) ng/ml. plasma lh concentrations declined to a basal level of 1.3 +/- 1.0 ng/ml within 48 h of the peak value. the duration of the lh surge was 1-3 days ... | 1984 | 6537978 |
| soluble mn2+-dependent adenylate cyclase activity in the testis of the blue fox (alopex lagopus). | soluble mn2+-dependent adenylate cyclase (mnac) activity was found in testicular cytosol from blue foxes castrated during the breeding season. the rate of mnac activity was approximately constant for 30 min at 35 degrees c and for 2 hr after storage at 25 degrees c. activity was directly proportional to cytosol protein concentration and was optimal in the physiological ph range. enzyme activity declined in the presence of an alkylating agent (n-ethyl maleimide, nem) and was eliminated at a conce ... | 1984 | 6508430 |
| karyotypic kinship between the blue fox (alopex lagopus linn.) and the silver fox (vulpes fulva desm.). | a karyotypic comparison between the blue fox and the silver fox revealed conservation of the chromosome arm as a unit, except for large heterochromatic blocks in 10 pairs of blue fox chromosomes and the complete absence of a common metacentric autosomal pair. this finding seems to indicate that their karyotypes evolved from a common ancestral karyotype, characterized by 70-76 acrocentric autosomes, mainly through a series of independent centric fusions. | 1983 | 6861523 |
| ovarian and testicular function in the blue fox (alopex lagopus) after oral administration of fenchlorphos during the breeding season. | | 1983 | 6193696 |
| activities of some enzymes in the tissues of the blue fox (alopex lagopus). | the activities of aspartate aminotransferase (ast), alanine aminotransferase (alt), ornithine carbamoyltransferase (oct), sorbitol dehydrogenase (sdh), gamma-glutamyl transferase (ggt), alkaline phosphatase (ap), lactate dehydrogenase (ldh) and creatine kinase (ck), were determined in eight organs of 10 healthy male blue foxes. oct was absolutely liver specific and alt was also found to be liver specific. sdh was also found primarily in the liver but its activity was relatively low. ggt was foun ... | 1982 | 6130587 |
| [use of marker genes located on x-chromosomes to analyze lens development in arctic fox/fox hybrids]. | glucose-6-phosphate dehydrogenase (g6pd) isozymes were studied in the lens and some tissues of arctic fox x fox female hybrids at different developmental stages. during the embryonic and early postnatal (till the 2nd day of life) development the lens is characterized by a high degree of individual variation of the ratio between parental g6pd forms. the number of stem cells for the lens was determined to be equal to six by means of binomial method of description of this variation. taking into acc ... | 2006 | 6953392 |
| fine structure and fsh binding of sertoli cells in the blue fox (alopex lagopus) in different stages of reproductive activity. | a clearly different sertoli cell morphology was found in the immature blue fox and in the adults in and out of season. immature cells had small, basally, located nuclei rich in peripheral heterochromatin, and few cytoplasmic organelles. sertoli cells from adults in season had basally located, large, convoluted nuclei with homogenous nucleoplasma and prominent nucleoli. the basal and intermediate parts of the cytoplasm contained an extensively developed er, numerous mitochondria, free ribosomes, ... | 1981 | 6274805 |
| intestinal adenomatosis in a blue fox (alopex lagopus). | | 1981 | 7467088 |
| spontaneous rickets in the wild arctic fox alopex lagopus. | normal and rachitic, skeletally immature arctic foxes (alopex lagopus) were subjected to physical examination, roentgenographic studies, and in some cases histologic studies. the involved animals had active rickets coupled with antecedent normal diaphyseal bone formation. evaluation of all the long bones showed highly variable manifestations of the disease, which undoubtedly reflect different rates of physeal endochondral transformation and metaphyseal remodeling. histologic examination showed d ... | 1981 | 7336215 |
| toxic and carcinogenic effects of dimethylnitrosamine (dmna) in the blue fox (alopex lagopus). | | 1981 | 7201231 |
| cranial measurements in the arctic fox (alopex lagopus). | the skulls of 36 adult arctic foxes (alopex lagopus) of known sexes were measured in two canadian subspecies. significant differences (p less than or equal to 0.05) were found within and between the sexes of the two subspecies of arctic foxes. the identification of sexes is easier in the subspecies innuitus than in the subspecies groenlandicus. when the sexes of both subspecies are considered, the distinction between innuitus and groenlandicus becomes much more difficult. | 1980 | 7433722 |
| [crossing blue fox (alopex lagopus) to red fox (vulpes vulpes) using artificial insemination]. | an experiment with breeding red fox to blue fox by artificial insemination is described. the conception rate obtained was low. of five blue fox vixens three whelped, and average litter size was 6.5. none of the six red fox vixens whelped. examination of semen from the hybrid males showed aspermia. the testosterone levels in the male hybrids were significantly lower than those in male blue fox, the difference was less outstanding between the hybrids and the red fox males. the histological investi ... | 2013 | 7383839 |
| oestradiol-17 beta concentrations in the peripheral plasma of the blue fox (alopex lagopus) around oestrus. | | 1980 | 7386323 |
| [endocrine function of the ovaries of blue foxes (alopex ladopus) during postnatal ontogenesis]. | progesterone, androgen and estradiol levels in the blood plasma were radioimmunologically studied in female alopex lagopus aged 2 to 9 months with different weight at birth. the blood sex steroid level showed a sharp elevation at the age of 4 months. the weight gain stops by this time. thus, by the age of 4 months in females the sexual system becomes mature. from the age of 5 to 8 months there is a fall of the blood sex hormones, corresponding to anestrus, and by the age of 9 months there is a s ... | 2016 | 574963 |
| allelic expression in intergeneric fox hybrids (alopex lagopus x vulpes vulpes). iii. regulation of the expression of the parental alleles at the gpd locus linked to the x chromosome. | the electrophoretic pattern of glucose-6-phosphate dehydrogenase (g6pd) was studied in 60 intergeneric fox hybrids (alopex lagopus x vulpes vulpes), 33 females and 27 males. it is shown that the structural gene for g6pd, designated gpd, is located on the x chromosome in both arctic and silver foxes. analysis of g6pd patterns in the erythrocytes of hybrid females demonstrated that the phenotypic expression of parental alleles at the gpd locus varied considerably: from 1:1 to the hemizygous manife ... | 1978 | 565634 |
| fine structure of spermatogonia and spermatocytes in the blue fox (alopex lagopus). | | 1978 | 696536 |
| the composition and distribution of pcb in arctic fox (alopex lagopus) caught near longyearbyen on svalbard. | samples from 44 arctic foxes (alopex lagopus), caught near longyearbyen on svalbard, were analyzed with respect to their content of pcb. gas chromatographic-mass spectrometric investigations revealed that 7 pcb components constituted the main part of the total pcb present. these components were quantified individually. a moderate degree of pcb contamination was recorded. calculated on a fat weight basis, the total concentrations of pcb in fat tissue and liver were about equal, but the relative a ... | 1978 | 414518 |
| allelic expression in intergeneric fox hybrids (alopex lagopus x vulpes vulpes). ii. erythrocyte glucose-6-phosphate dehydrogenase in artic and silver foxes: purification and properties. | the functional properties of purified glucose-6-phosphate dehydrogenase (g6pd) from the erythrocytes of artic foxes (alopex lagopus) and silver foxes (vulpes vulpes) were investigated. it was found that ph optima for g6p d range from 8.15 to 8.25 in arctic foxes and from 10.2 to 10.4 in silver foxes. for g6p, the estimated km values were 74 x 10(-6) m (at ph 8.2) and 166 x 10(-6) m (at ph 10.2) in artic foxes and 58 x 10(-6) m (at ph 10.2) and 40 x 10(-6) m (at ph 8.2) in silver foxes. the km va ... | 1977 | 849247 |
| the effect of o,o-dimethyl-o-(2,4,5-trichlorophenyl) phosphorothioate (fenchlorphos) on cholinesterases in the blue fox (alopex lagopus). | | 1977 | 71852 |
| allelic expression in intergeneric fox hybrids (alopex lagopus x vulpes vulpes). i. comparative electrophoretic studies on blood enzymes and proteins in arctic and silver foxes. | twenty-seven blood enzymes and proteins, whose structures are presumably controlled by at least 33 genes, were assayed in arctic and silver foxes by starch gel electrophoresis. two types of protein and enzyme electrophoretic patterns were distinguished: one exhibiting a single enzyme, the other several isozymes. the two fox species were found to differ in seven of the 27 enzymes and proteins studied: glucose-6-phosphate dehydrogenase, adenylate kinase, erythrocyte carboxylesterase, diaphorase, p ... | 1976 | 1016223 |
| [expression of homologous genes in interspecies arctic fox x silver fox hybrids (alopex lagopus x vulpes vulpes). iii. mechanisms of expression of alleles of locus gpd, located on the x-chromosome]. | the electrophoretic pattern of glucose-6-phosphate dehydrogenase (g-6-pd) was studied in 60 intergeneric fox hybrids (alopex lagopus x vulpes vulpes), 33 females and 27 males. it is shown that the structural gene for g-6-pd, designated as gpd, is located on the x-chromosome in both arctic and silver foxes. analysis of g-6-pd in the erythrocytes of hybrid females demonstrated that the phenotypic expression of parental alleles at the locus gpd varied considerably: from 1:1 to the hemizygous manisf ... | 1976 | 1010322 |
| [homologous gene expression in intergeneric fox hybrids (alopex lagopus x vulpes vulpes). i. comparative electrophoretic analysis of blood proteins and enzymes in arctic and silver foxes]. | a comparative study of 27 enzymes and proteins in blue and silver foxes was carried out by means of starch gel electrophoresis. the structure of these enzymes and proteins is determined by about 33 genes. it is shown that a number of blood enzymes and proteins of these species is represented by a single electrophoretic form, while lactate dehydrogenase, carboanhydrase, arylesterase, carboxylesterase, diaphorase, hexokinase and tetrasolium oxidase have several forms. it is also found that these s ... | 1975 | 1218728 |
| records of cestodes in varying lemmings and an arctic fox from bathurst island, northwest territories. | | 1974 | 4434281 |
| the fatty acid composition of subcutaneous, omental and inguinal adipose tissue in the arctic fox (alopex lagopus innuitus). | | 1974 | 4416271 |
| transplacental transmission of nosema cuniculi in the blue fox (alopex lagopus). | | 1974 | 4528089 |
| effects of ovariectomy on the plasma progesterone and maintenance of gestation in the blue fox, alopex lagopus. | | 1974 | 4816938 |
| the fine structure of the lutein cells in the blue fox (alopex lagopus) with special reference to the secretory activity during pregnancy. | | 1974 | 4371005 |
| progesterone concentrations in the peripheral plasma of the blue fox (alopex lagopus) during pregnancy and the oestrous cycle. | | 1973 | 4761680 |
| [further studies on the effect on the feeding helminthofauna to alopex lagopus l]. | | 1964 | 14346943 |
| host-parasite relations in initiation of infection: i. occurrence of listeriosis in arctic mammals, with a note on its possible pathogenesis. | a lemming colony maintained at fort churchill was examined for the possibility of the presence of l. monocytogenes in latent form, but the organism was not isolated. following transfer of the lemmings from churchill to kingston, l. monocytogens was isolated. in speculation on the pathogenesis of listerosis, the author suggests that an upset carbohydrate metabolism may be involved in the trigger mechanism. the isolation of l. monocytogenes from a seemingly ill arctic fox caught at fort churchill ... | 1959 | 17649197 |
| surveillance of ixodes ricinus ticks (acari: ixodidae) in iceland. | ixodes ricinus is a three-host tick, a principal vector of borrelia burgdorferi (s.l.) and one of the main vectors of tick-borne encephalitis (tbe) virus. iceland is located in the north atlantic ocean with subpolar oceanic climate. during the past 3-4 decades, average temperature has increased, supporting more favourable conditions for ticks. reports of i. ricinus have increased in recent years. if these ticks were able to establish in a changing climate, iceland may face new threats posed by t ... | 2017 | 29017579 |
| emission changes dwarf the influence of feeding habits on temporal trends of per- and polyfluoroalkyl substances in two arctic top predators. | we monitored concentrations of per- and polyfluoroalkyl substances (pfass) in relation to climate-associated changes in feeding habits and food availability in polar bears (ursus maritimus) and arctic foxes (vulpes lagopus) (192 plasma and 113 liver samples, respectively) sampled from svalbard, norway, during 1997-2014. pfass concentrations became greater with increasing dietary trophic level, as bears and foxes consumed more marine as opposed to terrestrial food, and as the availability of sea ... | 2017 | 28918622 |
| vole abundance and reindeer carcasses determine breeding activity of arctic foxes in low arctic yamal, russia. | high latitude ecosystems are at present changing rapidly under the influence of climate warming, and specialized arctic species at the southern margin of the arctic may be particularly affected. the arctic fox (vulpes lagopus), a small mammalian predator endemic to northern tundra areas, is able to exploit different resources in the context of varying tundra ecosystems. although generally widespread, it is critically endangered in subarctic fennoscandia, where a fading out of the characteristic ... | 2017 | 28915877 |