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PubMed2003

Evolutionary implications of a high selfing rate in the freshwater snail Lymnaea truncatula.

Self-compatible hermaphroditic organisms that mix self-fertilization and outcrossing are of great interest for investigating the evolution of mating systems. We investigate the evolution of selfing in Lymnaea truncatula, a self-compatible hermaphroditic freshwater snail. We first analyze the consequences of selfing in terms of genetic variability within and among populations and then investigate how these consequences along with the species ecology (harshness of the habitat and parasitism) might govern the evolution of selfing. Snails from 13 localities (classified as temporary or permanent depending on their water availability) were sampled in western Switzerland and genotyped for seven microsatellite loci. F(IS) (estimated on adults) and progeny array analyses (on hatchlings) provided similar selfing rate estimates of 80%. Populations presented a low polymorphism and were highly differentiated (F(ST) = 0.58). Although the reproductive assurance hypothesis would predict higher selfing rate in temporary populations, no difference in selfing level was observed between temporary and permanent populations. However, allelic richness and gene diversity declined in temporary habitats, presumably reflecting drift. Infection levels varied but were not simply related to either estimated population selfing rate or to differences in heterozygosity. These findings and the similar selfing rates estimated for hatchlings and adults suggest that within-population inbreeding depression is low in L. truncatula.

Alleles↗
PubMedDate not supplied

[Genetic influence on energy requirements. I. Development of an experimental model].

In attempting to explore the mechanisms of interaction of genetic and environmental factors that affect the quantitative requirements of energy by man, the convenience of an animal model was considered and searched for. The idea was to start with male and female Wistar rats and through inbreeding segregate the highly effective users of energy from the poor users. The efficiency of dietary energy utilization was measured by the index of conversion (IC) defined as the dietary intake necessary to increase 1 g of body weight in a 32-day period, from day 21st to day 52nd of extrauterine life. The median value of the IC for all animals included in each experiment was the cut-off point to classify each individual as a good or a poor energy user. The first generation had three males and five females with a median IC = 2.90 and a range from 2.54 to 3.25. The proportion of males below the median was 3/3 while the proportion of females was 2/5. The difference in proportions was striking and led immediately to the consideration of a sex-link hypothesis, and to test it the, IC of 91 Wistar rats randomly selected at birth was obtained. The median value of the series was 2.99 with a range from 2.24 to 3.95. The proportion of male rats with values below the median was 33/38 while the corresponding proportion for females rats was 13/53. In other words, while nine of every ten male animals were good users of energy, only two out of ten females fell into this category.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Clinical and laboratory findings associated with actual or suspected azoospermia in dogs: 18 cases (1979-1990).

Eighteen dogs were evaluated for azoospermia, 8 of which had sired pups. On the basis of history, physical examination, and various laboratory evaluations, the cause and site of azoospermia varied. Two dogs that had never sired pups had likely been azoospermic from puberty (congenital azoospermia). Two dogs were azoospermic as a result of tumors (Sertoli cell tumor and malignant astrocytoma of the pituitary gland). Deposits of IgG were observed in testicular biopsy samples, which suggested an auto-immune cause for azoospermia in 5 dogs. One of the 5 dogs with IgG deposits in testicular tissues also had evidence of immune-mediated thyroiditis. Culturing of microbes in the semen was not helpful in determining potential causes of azoospermia, and results did not correlate with organisms isolated from testicular biopsy samples or with the finding of inflammation in biopsy samples. Because 6 dogs had relatives with histories of reproductive dysfunction, inbreeding also must be considered when evaluating dogs for azoospermia.

Alkaline Phosphatase↗
PubMed2004

Ace Alu insertion polymorphism in Croatia and its isolates.

Alu elements are a family of interspersed repeats in the genome propagating by retroposition into new chromosomal locations. Alu insertion in Ace gene is known to be polymorphic (presence/absence of Alu element) in worldwide populations and as such serves as marker for population structure analyses. In this study we examined the distribution of genotypes and allele frequencies of this polymorphism in general Croatian population and its two isolates (the island of Hvar and the coastal region of the Middle Dalmatia) and related them to the level of endogamy as an indicator of inbreeding in these populations. Results showed that these three population groups are different with respect to Ace Alu polymorphism. The endogamy was highest on the island of Hvar. With the increase of endogamy a decrease in heterozigosity was observed. The same trend was observed for the frequency of insertion allele. Its frequencies in the village subpopulations of two studied isolates are subject to genetic drift due to small population sizes and high levels of endogamy. This in turn causes genetic differentiation among villages that is observed to be higher on the island of Hvar than in the coastal region. In the worldwide perspective, the Ace Alu insertion allele frequency of 50.6% in the general Croatian population falls within the range of other European populations.

Adult↗
PubMed2005

[Genetic risks in plant ex situ conservation].

Conserving genetic diversity of rare and endangered species and their evolutionary potential is one of the long-term goals of ex-situ conservation. Some potential genetic risks in ex-situ conservation in botanical gardens are presented. The preserved species may lack genetic representativity because of poor sampling. Inappropriate plantations, inadequate records and unclear kinships jeopardize endangered species to genetic confusion, inbreeding depression or outbreeding depression. Artificial selection and habitat conversion also potentially result endangered plants in adapting to ex-situ conservation, which had been usually overlooked. All the genetic risks can decrease the success of reintroduction and recovery. Therefore, appropriate genetic management should be carried out in botanical gardens to decrease or avoid genetic risks in ex-situ conservation.

Adaptation, Biological↗
PubMed2005

Breakdown of self-incompatibility in the perennial Arabidopsis lyrata (Brassicaceae) and its genetic consequences.

Mating systems in plants are known to be highly labile traits, with frequent transitions from outcrossing to selfing. The genetic basis for breakdown in self-incompatibility (SI) systems has been studied, but data on variation in selfing rates in species for which the molecular basis of SI is known are rare. This study surveyed such variation in Arabidopsis lyrata (Brassicaceae), which is often considered an obligately outcrossing species, to examine the causes and genetic consequences of changes in its breeding system. Based on controlled self-pollinations in the greenhouse, three populations from the Great Lakes region of North America included a minority of self-compatible (SC) individuals, while two showed larger proportions of SC individuals and all populations contained some individuals capable of setting selfed seeds. Loss of SI was not associated with particular haplotypes at the S-locus (as estimated by alleles amplified at the SRK locus, the gene controlling female specificity) and all populations contained similar numbers of SRK alleles, suggesting that some other genetic factor is responsible for modifying the SI reaction. The loss of SI has resulted in an effective shift in the mating system, as the two populations with a high frequency of SC individuals showed significantly lower microsatellite-based multilocus outcrossing rates and higher inbreeding coefficients than the other populations. Based on microsatellites, observed heterozygosities and genetic diversity were also significantly depressed in these populations. These findings provide the unique opportunity to examine in detail the consequences of mating system changes within a species with a well-characterized SI system.

Analysis of Variance↗
PubMed2005

Evaluating the costs of mosquito resistance to malaria parasites.

Costly resistance mechanisms have been cited as an explanation for the widespread occurrence of parasitic infections, yet few studies have examined these costs in detail. A malaria-mosquito model has been used to test this concept by making a comparison of the fitness of highly susceptible lines of mosquitoes with lines that are resistant to infection. Malaria infection is known to cause a decrease in fecundity and fertility of mosquitoes; resistant mosquitoes were thus predicted to be fitter than susceptible ones. Anopheles gambiae were selected for refractoriness/resistance or for increased susceptibility to infection by Plasmodium yoelii nigeriensis. Additional lines that acted as controls for inbreeding depression were raised in parallel but not exposed to selection pressure. Selections were made in triplicate so that founder effects could be detected. Resistance mechanisms that were selected included melanotic encapsulation of parasites within 24 h postinfection and the complete disappearance of parasites from the gut. Costs of immune surveillance were assessed after an uninfected feed, and costs of immune deployment were assessed after exposure to infection and to infection and additional stresses. Mosquito survivorship was unaffected by either resistance to infection or by an increased burden of infection when compared with low levels of infection. In most cases reproductive fitness was equally affected by refractoriness or by infection. Resistant mosquitoes did not gain a fitness advantage by eliminating the parasites. Costs were consistently associated with larval production and egg hatch rate but rarely attributed to changes in blood feeding and never to changes in mosquito size. No advantages appeared to be gained by the offspring of resistant mosquitoes. Furthermore, we were unable to select for refractoriness in groups of mosquitoes in which 100% or 50% of the population were exposed to infection every generation for 22 generations. Under these selection pressures, no population had become completely refractory and only one became more resistant. Variations in fitness relative to control lines in different groups were attributed to founder effects. Our conclusion from these findings is that refractoriness to malaria is as costly as tolerance of infection.

Animals↗
PubMed2006

Minimal selfing, few clones, and no among-host genetic structure in a hermaphroditic parasite with asexual larval propagation.

Little is known about actual mating systems in natural populations of parasites or about what constitutes the limits of a parasite deme. These parameters are interesting because they affect levels of genetic diversity, opportunities for local adaptation, and other evolutionary processes. We expect that transmission dynamics and the distribution of parasites among hosts should have a large effect on mating systems and demic structure, but currently we have mostly speculation and very few data. For example, infrapopulations (all the parasites in a single host) should behave as demes if parasite offspring are transmitted as a clump from host to host over several generations. However, if offspring are well mixed, then the parasite component population (all the parasites among a host population) would function as the deme. Similarly, low mean intensities or a high proportion of worms in single infections should increase the selfing rate. For species having an asexual amplification stage, transmission between intermediate and definitive (final) hosts will control the variance in clonal reproductive success, which in turn could have a large influence on effective sizes and rates of inbreeding. We examined demic structure, selfing rates, and the variance in clonal reproductive success in natural populations of Plagioporus shawi, a hermaphroditic trematode that parasitizes salmon. Overall levels of genetic diversity were very high. An a posteriori inference of population structure overwhelmingly supports the component population as the deme, rather than individual infrapopulations. Only a single pair of 597 adult individuals was identified as clones. Thus, the variance in clonal reproductive success was almost zero. Despite being hermaphroditic, P. shawi appears to be almost entirely outcrossing. Genetic estimates of selfing (<5%) were in accordance with the proportion of parasites from single infections. Thus, it appears that individual flukes outcross whenever possible and only resort to selfing when alone. Finally, our data support the hypothesis that aquatic transmission and the use of several intermediate hosts promotes high genetic diversity and well-mixed infrapopulations.

Animals↗
PubMed2006

[Medical genetic study of the Rostov oblast population: analysis of surname distribution in seven districts].

Data on the surname frequency distribution in seven districts (districts) of the Rostov oblast (region) have been used to calculate random inbreeding varying from 0.000064 to 0.000186 in the Volgodonsk and Millerovo districts, respectively. Schematic surname landscapes have been constructed for six districts. The observed spectrum of frequent surnames is compared with that of the complete register of surnames in Russia.

Female↗
PubMed2006

[Case report: congenital myoclonus in a German Holstein calf].

A female German Holstein calf was not able to stand up after birth. Resting the animal was lying in normal position and could lift its head. Sensory stimuli like auditory or tactile impulses induced myoclonic jerking of the whole body. Afterwards it calmed down quickly. The signs observed correspond to the clinical findings of congenital myoclonus in poll Hereford calves. The pathological examination revealed no indications for changes in organs. The inbreeding coefficient of the calf was 1.56 %. The present type of congenital myoclonus in the calf examined is likely to be genetically determined, even if the point mutation in exon 2 of the glycin receptor alpha 1 gene was not confirmed.

Animals↗
PubMed2006

[Microsatellite DNA monitoring in inbred cultivation of outbred rats].

Microsatellite DNA was used to monitor the gene inheritance of successive generations of rats. It is useful in selective breeding to quickly bring genes to homozygosity and to shorten the cultivation periods of new inbreeding of rats. Thirty microsatellite DNA loci were PCR amplified to analyze the DNA polymorphism in generational crosses between the outbred Wistar and SD rats. Rats in F generations with a moderate to high coefficient of similarity with the female F0 SD rats were crossed. All loci in the F2 generation were heterozygous and polymorphic. By F9, 27 loci have become homozygotic, with a homozygosity rate of 90%. The coefficient of similarity tended to increase at a rate of 6%-20% with each successive generation. Skin grafting confirmed no rejection among the F9 generation of rats. Therefore we have established a novel method for rapid cultivation of inbred rats.

Animals↗
PubMed2006

[Case report: arhinia and cyclopia in a German Fleckvieh calf].

A German Fleckvieh calf was diagnosed with cyclopia in shape of united eye sockets in one orbit. However, two fully developed eye balls were present while the nostril was not developed. The malformed calf was inbred on a bull used for artificial insemination (AI) with an inbreeding coefficient of 3.125%. Teratogenic plant alkaloids were unlikely to be responsible for the malformation of this calf. Neither in the five progeny of the dam nor in the descendants of the AI-bull with a total of 8083 calvings, calves with such anomalies were found.

Animals↗
PubMed2006

[Case report: Ectopia cordis in a German Holstein calf].

A case of ectopia cordis pectoralis was diagnosed in a black and white coloured German Holstein calf. The heart and pericard were displaced through a fissure in the breastbone. The heart was connected with the thoracic cavity by its large vessels. Besides of the ectopia cordis no other defects of the heart were noticed. The liver was deformed and many organs showed passive hyperaemia. The calf was well developed and died under birth. The lungs were not ventilated. The malformed calf was inbred on a bull used for artificial insemination with an inbreeding coefficient of 3.125%. The ectopia cordis probably resulted from the fissure of the breastbone.

Animals↗
PubMed2006

[Aphakia in a German Holstein calf].

Aphakia and further malformations of both eyes were diagnosed in a female German Holstein calf. Besides aphakia of the left eye, the calf exhibited microphthalmia, glaucoma and a hypoplastic uveoscleral tissue. Additional findings in the right eye were buphthalmus and glaucoma. Instead of aphakia, pathohistological and investigations revealed a very small (microphakia) and luxated lens. Neither the clinical nor the pathological examination revealed further malformations of other organs. A BVD infection could be excluded as cause for the ocular malformations observed. A deficiency or excess of vitamine A was unlikely because this would have also applied to all other calves born at the same time on the farm. An inbreeding coefficient of 3.168% for the malformed calf and the exclusion of environmental causes for these malformations of the eyes let us suppose a hereditary problem.

Animals↗
PubMed1991

Pre-implantation embryo development in BALB/C ByJ mice.

Problem of failure of ovum implantation in BALB/C ByJ strain in comparison to Swiss inbred mouse was studied. The results were compared with those of BALB outbred mice thereafter. BALB/C ByJ strain showed a poor responsiveness to superovulatory stimuli and their embryo development was not uniform. The embryo were delayed in attaining blastocyst stage on day 4. The delay was not significant in Swiss inbred embryos and was prevented by in vitro cultures. By direct embryo transfer it was shown that the uterus was not receptive for successful implantation. However, when these blastocysts were transferred to F1 hybrid (CBA x BALB outbred) recipients demonstrated normal acceptances. This may be a manifestation of inbreeding depression.

Animals↗
PubMed1991

Streptococcus canis arthritis in a cat breeding colony.

This is the first description of a pathologic condition--arthritis in cats affecting mainly one joint, i.e. monarthritis--caused by Streptococcus canis (S. canis), of the Lancefield serologic group G. Six cases were recorded in a closed cat breeding colony during a 6 month period in 1988, and one additional case in 1990. Therapy with penicillin and streptomycin led to full recovery in four of six cases. The bacterium had been detected from different purulent processes sporadically--including one case of purulent arthritis in 1982--as a nosocomial infection since 1980, the year the breeding colony was established. A possible genetic predisposition (high inbreeding) may have contributed to the accumulation of the six cases in 1988. Although S. canis was isolated in mouse, rat, rabbit and dog, cat and man seem to be more frequently affected. There are some similarities between S. canis-arthritis in cat and man.

Animals↗
PubMed1990

Familial incidence of multiple births in a colony of chimpanzees (Pan troglodytes).

This paper describes the incidence of multiple births in the Yerkes Chimpanzee colony for a period of about 63 years. Pedigrees are presented for all multiple births. They demonstrate the recurrence of twins in relatively few family lines which can be traced back to a small number of ancestors. The findings suggest that twinning is a family trait in chimpanzees and they support the hypothesis that the incidence of multiple births is genetically influenced in this colony. In addition, a relatively high level of inbreeding may have enhanced the incidence of multiple births in these family lines. Similar findings are known from human populations.

Animals↗
PubMed1986

Pedigree analysis of Abyssinian cats with familial amyloidosis.

Pedigrees of 62 Abyssinian cats with familial amyloidosis were compared with those of 100 Abyssinian cats registered with the Cat Fanciers Association. The inbreeding coefficients of the 2 samples of cats were not significantly different. Analysis of the pedigrees with respect to specific ancestors, however, showed that certain cats were significantly more common in the pedigrees of affected cats than in those of cats in the randomly selected sample. These data support a genetic basis for this disease, but do not allow determination of the mode of inheritance.

Amyloidosis↗

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