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PubMed1999

Genetics of the female reproductive ducts.

Familial aggregates of the most common disorders of müllerian differentiation in females-Müllerian aplasia, incomplete Müllerian fusion-are best explained on the basis of polygenic/multifactorial inheritance. No information exists on the number and chromosomal location of responsible genes. Single mutant genes (Mendelian) are responsible for the McKusick-Kaufman syndrome (MKS) and the hand-foot-genital syndrome. The molecular basis for the latter condition involves HOXA13, but the molecular basis of MKS and other disorders of the female reproductive ducts is unknown. Vaginal atresia, Müllerian aplasia, and incomplete Müllerian fusion are not infrequently observed in malformation syndromes.

Cervix Uteri↗
PubMed1996

Significant competitive advantage conferred by meiosis and syngamy in the yeast Saccharomyces cerevisiae.

The presumed advantages of genetic recombinations are difficult to demonstrate directly. To investigate the effects of recombination and background heterozygosity on competitive ability, we have performed serial-transfer competition experiments between isogenic sexual and asexual strains of the yeast Saccharomyces cerevisiae. The members of these diploid pairs of strains differed only in being heterozygous (sexual) or homozygous (asexual) at the mating type or MAT locus. Competing pairs had either a completely homozygous or a heterozygous genetic background, the latter being heterozygous at many different loci throughout the genome. A round of meiotic recombination (automixis) conferred a large and statistically significant enhancement of competitive ability on sexual strains with a heterozygous genetic background. By contrast, in homozygous background competitions, meiosis decreased the sexual strains' initial relative competitive ability. In all cases, however, the sexual strains outcompeted their isogenic asexual counterparts, whether meiotic recombination had occurred or not. In some genetic backgrounds, this was due in part to an overdominance effect on competitive advantage of heterozygosity at the MAT locus. The advantage of the sexual strains also increased significantly during the course of the homozygous background competitions, particularly when meiosis had occurred. This latter effect either did not occur or was very weak in heterozygous background competitions. Overall, sexual strains with heterozygous genetic backgrounds had a significantly higher initial relative competitive ability than those with homozygous backgrounds. The advantage of mating type heterozygosity in this organism extends far beyond the ability to recombine meiotically.

Biological Evolution↗
PubMed2003

Origin usage during euplotes ribosomal DNA amplification.

The macronuclear genome of the ciliate Euplotes is comprised of millions of small linear DNA molecules that have telomeres on each end. These molecules are generated during the sexual stage of the life cycle, when the new macronucleus is formed by a series of DNA processing events and multiple rounds of DNA amplification. We have used two-dimensional gels to compare the location of the replication origins used during vegetative growth and the two periods during macronuclear development when DNA amplification takes place. When we examined the pattern of ribosomal DNA (rDNA) replication intermediates, we observed almost identical Y arcs regardless of when in the Euplotes life cycle the DNA was isolated. No bubble or bubble-to-Y arcs could be detected. This indicates that replication of the macronuclear rDNA initiates at or near the telomere even when these molecules are being differentially amplified. Since replication rarely initiated from both ends of the rDNA, we examined the direction of replication fork movement to determine which end of the rDNA served as the origin. Fork movement gels indicated that replication initiated at the 5' end. As transcription also starts near the telomere at the 5' end, our findings suggest that the telomere and the promoter region cooperate to recruit Euplotes replication initiation complexes.

Animals↗
PubMed1999

The Creatures global digital ecosystem.

An artificial life entertainment software product called Creatures was released in Europe in late 1996 and in the United States and Japan in mid-1997. When installed on a domestic computer (PC or Macintosh), each Creatures CD-ROM creates a virtual world in which autonomous software agents exist. The agents, known as "norn," interact with the human user, with each other, and with objects in their virtual world. Each norn coordinates perception and action via its own modular recurrent neural network. Each network has Hebbian learning, plus diffuse modulation of activity via a "hormonal" system that is part of that norns "biochemistry." Details of each norns neural network and biochemistry are genetically specified, and norns can breed via sexual reproduction. In the reproduction process, genetic material may be mutated and may also be subjected to "gene duplications" that enable potentially unlimited increases in complexity of the norns' design. Over 500,000 Creatures CD-ROMS have now been sold. As each installed copy of Creatures can support 5 to 10 simultaneously existing individual norns, it seems reasonable to estimate that there are up to 5 million norns existing in the "cyberspace" provided by the global Creatures user community. Continued growth of the global norn population, to figures measured in tens of millions, is quite likely. Although a commercial product, the Creatures digital ecosystem should be of interest to artificial life scientists. There are obvious parallels with Yaeger's PolyWorld and Ray's NetTierra systems. This article provides a detailed discussion of the links between the artificial life literature and the technology used in Creatures and includes anecdotal discussion of the "digital naturalism" witnessed on the many independent websites maintained by Creatures enthusiasts.

Biochemical Phenomena↗
PubMed1991

Genetics of growth and reproduction in the turkey. 12. Results of long-term selection for increased 180-day egg production.

A line of turkeys selected 28 generations for increased 180-day egg production (E) was compared through regression analysis with the randombred control population (RBC1) from which it originated. The only curvilinear trends observed for RBC1 were for egg weight and 8-wk (both sexes) and 16-wk (males) BW. Linear declines in egg production and rate of lay through 84 and 180 days of lay, the number of clutches during the 180-day production period, effective days of egg production, and 16-wk (females) and 20-wk (both sexes) BW were observed for RBC1. The RBC1 turkeys had linear increases in the percentage of broody hens during the first 84 and 180 days of production, the average length of the broody period, and the total number of days lost to broodiness during the 180-day period. When expressed as a deviation from RBC1, positive quadratic curvilinear changes were observed for E turkeys for number of clutches and broody periods, and days lost to broodiness during the first 180 days of production. Percentage hatch of fertile eggs at 8 and 12 wk of production also exhibited a positive quadratic change with generation. Linear increases in egg production, rate of lay, clutch length (average and maximum), number of effective days of production, and percentage hatch of fertile eggs 12 wk into production were observed for E turkeys. There were linear declines in number of days from photostimulation to the production of first egg, number of clutches, and number, average length, and days lost to broodiness for E line turkeys.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

[Genetic-epidemiologic study of reproductive outcomes in the Ozersk population, located in "Maiak" control area].

In the population of Ozyorsk town situated in the control area of the nuclear enterprise (Production Association "Mayak") the number of pregnancies and its outcomes was studied in cohort of 2.258 women of completed fertility. The mean number of pregnancies per woman is 5.6 +/- 0.07. The mean size of family is 1.9 +/- 0.02. It was estimated that 2.7% of women had no pregnancies, 4.0% of women had no delivery till the end of their reproductive performance. 4.65% of women contributed nothing to the genofond of the next generation, i.e., they had not any children lived till their reproductive performance (20 years). The Crow Index of Opportunity for Selection and its components connected with differential fertility and differential mortality were estimated. In the population under study tow components of selection--selection at the prenatal stages (72.6%) and selection associated with infertility--are shown to be significant.

Cohort Studies↗
PubMed2005

[The effect of reproduction biotopes on the genetic differentiation of populations of sockeye salmon Oncorhynchus nerka].

Variation of mitochondrial DNA (mtDNA) was examined in nine populations from three lake-river systems of Chukotka and Kamchatka. Significant differences were found between most of the sockeye salmon samples studied. The genetic differences among populations were not high and often did not correlate with the geographical distances between them. The low population divergence is explained by a short time of existence of most of them, having been formed after the recession of the upper Pleistocene glacier. When the populations were grouped according to their spawning biotopes (river or lake), they in general appeared more genetically similar than upon their grouping by geographical location (the lake-river systems). The differences between the river and lake populations in the lake--river systems increased from north to south.

Animals↗