[Effect of induced chromosomal rearrangements on the fertility and viability of Anopheles atroparvus]

Partial sterility in 3 strains of malarial mosquito Anopheles atroparvus with heterozygous chromosomal rearrangements In2(R;L) 1+In2L1; In3(R;L) 1+D3R1; T(2R;3R)1 was studied. Fertility of these lines was decreased 2.5 to 5 times, as compared with the control. No homozygotes for rearrangements were detected. Causes for partial sterility of insects with heterozygous insertions, translocations and the significance of constructing homozygous strains are discussed.

[Chromosome analysis of bulls in relation to disorders of sexual activity]

Chromosomal analysis was used for the examination of 16 bulls of different breeds from the Milhostov breeding station. The examined bulls exhibited disorders of sexual activity (disorders of spermiogenesis, aspermia, bad quality of semen, hypoplasia of testes, etc.). The examination was performed by the method after Moorhead et al. (1960) modified by Lojda et al. (1974): metaphase plates were evaluated microscopically (100 X 12) and from photos. The chromosomes were counted by means of the counting documator (from film negatives) and from photos. A card was prepared for each animal. Hyposomy (11 sires--68.75%) and hyperploidy (10 sires--62.5%) were found to be the most frequent numerical aberrations, followed by polysomy (4 sires--25.0%) and other aneuploidies (one case--6.2%). As to structural defects, breaks occurred in 14 sires (87.5%), bichromatid breaks in five sires (31.25%) and breaks on sexual chromosomes in three sires (18.75%). Centric fusion was observed in one case (6.25%), association in two cases (12.5%) and mixed aberrations in four cases (25.00%).

Cytogenetic investigations in 150 cases with complaints of sterility or primary amenorrhea

Cytogenetic investigations were carried out on 150 individuals. Out of these 107 were females and 43 males. Eighty seven of the above (43 males and 44 females) had been referred for sterility. Sixty three patients had primary amenorrhea and had been referred directly to this laboratory by clinicians, having been suspected of genetic abnormalities. Twenty-two cases (14.7%) involved in this study chromosomal abnormalities and seven cases (4.7%) showed chromosomal polymorphism. Of the 107 females (44 sterile and 63 with primary amenorrhea), 11 (10.2%) showed numerical or structural sex chromosomal abnormalities. Five patients (4.67%) showed chromosomal polymorphism (involving the paracentromeric and centromeric regions of chromosomes 1 and 9, double satellites, and giant satellites. Of the 43 males, 11 (25.59%) showed numerical and structural abnormalities. Ten cases were anomalies involving the sex chromosomes. One case of a triple autosomal translocation in an otherwise phenotypically normal azoospermic male was of particular interest. Two cases (4.65%) showed double satellites of the acrocentrics.

The molecular basis of P-M hybrid dysgenesis: the role of the P element, a P-strain-specific transposon family

We have shown previously that four of five white mutant alleles arising in P-M dysgenic hybrids result from the insertion of strongly homologous DNA sequence elements. We have named these P elements. We report that P elements are present in 30-50 copies per haploid genome in all P strains examined and apparently are missing entirely from all M strains examined, with one exception. Furthermore, members of the P family apparently transpose frequently in P-M dysgenic hybrids; chromosomes descendant from P-M dysgenic hybrids frequently show newly acquired P elements. Finally, the strain-specific breakpoint hotspots for the rearrangement of the pi 2 P X chromosome occurring in P-M dysgenic hybrids are apparently sites of residence of P elements. These observations strongly support the P factor hypothesis for the mechanistic basis of P-M hybrid dysgenesis.

Psychogenic factors in some genetic and non-genetic forms of infertility

Five categories of patients suffering from different genetic and non-genetic forms of infertility and three categories of similarly affected, but potentially fertile, clinically normal individuals were studied. The Eysenck's Personality Inventory (1964), Ryle's Marital Patterns Test (1966) and Leckie and Wither's Inventory for Depressive Illness (1967) were used to determine the role played by psychogenic factors in causing infertility. No significant quantitative or qualitative differences were observed in the various groups studied. The psychogenic disturbances present in these individuals appear to be the result of the effect of persisting infertility rather than the cause of it.

Contribution of chromosome abnormalities to human morbidity and mortality

Estimates of the association of chromosome aberrations with various adverse health outcomes are as follows: embryonic and fetal death (5-28 weeks), 33%; stillbirths, 5-10%; infant and early childhood death, 5-7%; retardation (IQ less than 50), 20-35%; (IQ 50-69), 5-15%; criminality an d retardation or psychiatric disturbance in males, 3%; other criminality, 0.3-0.8%; birth defects, 2.5-8%; heart defects, 10%; subfertility or infertility, 2-8%; multiple miscarriages, less than 1 to 13%; male pseudohermaphroditism, less than 25%; and primary amenorrhea, 25%. Variations in rates reflect statistical fluctuations and variations in the selection of populations for study. The estimates are based on currently used techniques; cryptic structural rearrangements may also contribute significantly to these outcomes.

X-autosome translocations: cytogenetic characteristics and their consequences

To define the principal characteristics of X-autosome translocations, the authors present a study of 105 cases, five of which are personal observations. The autosomal pairs 15, 21, and 22 are affected by t(X-Aut) more often than would be expected. The distribution of breakpoints on the X chromosome does not differ significantly from the expected distribution. The analysis of different patterns of inactivation seems to confirm that the inactivation could occur at random, but would be followed by a cellular selection favoring the better genetic balance. An estimate of the incidence of t(X-Aut) is proposed, based upon the conclusions that only one chromosome is susceptible to translocation in meiosis in both males and females and that all affected men will be sterile, as will be 50% of women.

Adenosine deaminase polymorphism. Associations at clinical level suggest a role in cell functions and immune reactions

It is well known that subjects homozygous for a rare silent allele of ADA may experience a severe combined immunodeficiency. By analogy we have investigated the possible relationship of normal ADA polymorphism with some situations, such as reproductive defects and fetomaternal interactions, in which immunological mechanisms may play an important role. A total of 572 consecutive newborns, 93 consecutive low birthweight infants, 46 couples with unexplained habitual abortion, and 24 couples with unexplained sterility were studied. The proportion of ADA 2-1 phenotype was reduced in couples with reproductive defects. In the sample of consecutive newborns the proportion of ABO incompatible babies was higher among ADA 2-1 than among ADA 1 types. ADA 2-1 phenotype was also associated with a reduction in the variability of gestational length. These associations were much more marked among male than among female babies. The proportion of ADA 2-1 was significantly lower in low birthweight infants than in the consecutively studied infants and normal adults. The present data suggest that biochemical variability resulting from the normal ADA polymorphism may be, at least in part, responsible for the variability of some immunological functions and related physiological variables and pathological conditions. They also provide evidence in favour of a selective advantage of ADA heterozygotes.

Suppression and function of X-linked lethal and sterile mutations in Caenorhabditis elegans

We have expanded our collection of recessive lethal and sterile mutants in the region of the X chromosome balanced by mnDp1(X;V), about 15% of the X linkage map, to a total of 54 mutants. The mutations have been mapped with respect to 20 overlapping deficiencies and five X duplications, and they have been assigned to 24 genes by complementation testing. Nine mutants are hermaphrodite-sterile: one of these is a sperm-defect mutant, two have abnormal gonadogenesis and six, in five genes, are maternally influenced mutants, producing inviable zygote progeny. One of the gonadogenesis mutants and two of the maternally influenced mutants are male fertile. All but one of the maternally influenced mutants give cross progeny when mated with wild-type males. Forty-three mutants were tested for suppression by homozygous sup-5 (e1464), which is believed to be specific for null alleles. Ten mutants that were judged by independent criteria not to be null mutants are not suppressed. Nine of the other 33 mutants, in nine genes, are suppressed, five in both heterozygous and homozygous suppressor stocks and four only in homozygous suppressor stocks.

Rapid unidirectional change of hybrid dysgenesis potential in Drosophila

Two main types of Drosophila melanogaster strains have been previously described in relation to hybrid gonadal sterility: P (paternally derived) and M (maternally derived). When M strain females are mated with P strain males, cytoplasm-chromosome interactions result in variable frequencies of sterility in their hybrid progeny. A third neutral strain type, Q, generally has no significant potential for sterility in any hybrid strain combination. Mixed populations of these three types of strains were set up in various combinations and initial frequencies. They were subsequently maintained without artificial selection and monitored for their gonadal sterility and potential. All 24 mixed cultures initiated with P and M parents independently evolved rapidly towards a state of at least moderate P activity, which was maintained in succeeding generations. The M cytotype was not maintained after 10-20 generations except at very low frequencies. Changes in sterility potential were less clear cut in those mixed populations that originally included neutral strain flies, but there was a tendency for the frequencies of sterility of the majority of PQ and QM mixed cultures to change in the same direction as for the P and M combinations. The results are discussed in terms of conventional mechanisms of segregation and selection and in terms of an alternative hypothesis of chromosome contamination in which sterility factors may be transposed from P to M chromosomes, resulting in extremely rapid unidirectional population changes. Possible implications of these results for general models of the evolution of hybrid dysgenesis are explored.

Response to divergent selection for nesting behavior in Mus musculus

Replicated bidirectional selection (with control lines) for nest-building behavior in Mus musculus, where nesting scores consisted of the total weight of cotton pulled through the cage lid during four days of testing, yielded an eight-fold difference between high and low lines after 15 generations of selection. The overall realized heritability pooled across lines and replicates was 0.18 +/- 0.02 (0.15 +/- 0.03 for high nesting scores and 0.23 +/- 0.04 for low nesting scores), or 0.28 +/- 0.05 when adjusted for within-family selection. Across the 15 generations and the entire experiment, average body weight and number of infertile matings increased, while average litter size decreased, although these changes were not consistent across lines. Inbreeding could account for average decreases in the fertility traits, but there was also a correlated response to selection, since both high lines showed increased litter size and decreased infertile matings.

Sterility in D. melanogaster due to nucleocytoplasmic interactions

A case of sterility in Drosophila melanogaster is due to the interaction between a second chromosome recessive conditional gene, str(2)350, recovered from a natural population and the cytoplasm. The gene is located between Sp(22.0) and B1(54.8) about one-eighth the distance from B1. The final effect of this interacting system is the suppression of gonad development in both sexes.

A cytogenetical analysis of sterile mutants in Caenorhabditis elegans

The regulation of gametogenesis in the hermaphrodite and proterandrous nematode Caenorhabditis elegans is introduced here through the analysis of nonconditional sterile mutants. To investigate the mechanisms which allow the two gametogenetic phases to succeed each other in the same ovotestis, three mutants were studied cytogenetically. Two of the mutants exhibit only the spermatocyte phase and the third shows a greatly reduced and disturbed oogenesis. These three mutations all produce large decreases in ovotestis size and gonocyte number. Each of the three is monofactorial, recessive, autosomal and independent. Homozygous mutant males are also sterile. The gametogenesis phases which could be disturbed by mutation were determined by cytological analysis of the ovotestis of 12 other sterile strains. These phases occur during mitotic divisions of the genital primordium, zygotene chromosome pairing, male meiosis and spermiogenesis, oogenesis induction and oocyte maturation. These steps of gametogenesis need a wild-type genic activity to occur normally. It appears that spermatogenesis and oogenesis are two genetically independent processes, and that oogenesis is rather autonomous and its induction would depend on a hormonal factor.

Cytogenetical studies of infertile pigs

Cytogenetical studies were made on 6 infertile pigs. Post-mortem examination of the reproductive organs of 5 of these pigs showed them to be intersexes. Regardless of the degree of gonadal deviation from the normal, chromosome karyotype of cultured peripheral blood lymphocytes, bone marrow, liver and kidney, revealed that 4 of the intersexes had a 38,XX constitution. One intersex exhibited sex chromosome mosaicism (38XX/38XY) in lymphocytes from the peripheral blood and bone marrow and a normal male karyotype (38XY) in cultured liver and kidney cells. The sixth pig, a phenotypically normal boar, also had a 38XX/38XY chromosome constitution.

Mutagen-sensitive mutants in Neurospora

Initial work on the fungus Neurospora crassa has shown that a least two DNA-repair systems exist in this eukaryote: excision repair and a mutation-prone repair. The evidence suggests that there is also a third repair system. Recently, new mutagen-sensitive strains have been isolated in several laboratories, but they are not yet fully characterized. A hunt for cytoplasmically inherited UV sensitivity has failed to turn up any such mutants among 25 new UV-sensitive isolates.

[Human chromosomal polymorphism and reproductive function disorder. III. Extreme autosomal C-variants: an analysis of their distribution and combination in the karyotype]

Distribution of extreme C-stained polymorphic variants of autosomes 1, 9, 13-16 21 and 22, alone and in combinations, was studied in married couples with reproductive failure (200 individuals) and in couples having normal children. There were no significant differences between the frequencies of extreme C-band variants (total and "plus"-variants) for two sexes in control group. Individuals of this group had combination of one of two extreme variants and one heteromorphic pair (out of three possible) pairs of chromosomes, 1, 9 and 16 per individual karyotype. There was a significant increase of the frequencies of extreme C-band variants (total and "plus"-variants) in women with reproductive failure comparing to the men of the same group and to the women of the controls. There was significant difference in frequencies of individuals with combination of three extreme C-band variants per one karyotype in women with the reproductive failure comparing to men of the same group.

Extrachromosomal control of mutability in Drosophila melanogaster

Hybrid dysgenesis is a syndrome of germ-line aberrations including, e.g., sterility and mutation, found in certain interstrain hybrids of Drosophila melanogaster. Previous studies of sterility have shown that elements responsible for dysgenesis may reside on all major chromosomes, but that their dysgenesis-causing ability is controlled by an unknown extrachromosomal factor. Dysgenic hybrids also give rise to unstable visible mutations thought to be DNA insertions at certain sensitive loci. One such unstable allele at the singed bristle locus, designated snw, was found to mutate at extraordinary rates exceeding 50%. This instability was shown to be under the same extrachromosomal control as hybrid dysgenesis itself. That is, the mutability of snw was reversibly suppressed when placed in the background cytotype known to prevent sterility and other characteristics of hybrid dysgenesis. These results suggest that snw may represent an insertion at the singed locus of a hypothetical gene responsible for hybrid dysgenesis.

[Pericentric inversions: studies in 47 cases]

The authors report 47 cases of pericentric inversion. Eleven of them involve the chromosomes No. 2, 11 and 9. It appears that the risk of malformations and/or encephalopathy is obviously increased either by "position effect", aneusomie de recombinaison" or "interchromosomal effect". Prenatal diagnosis is therefore indicated. Thirty six cases involve the secondary constriction of chromosome No. 9. In such cases the risk is not enough increased to justify the prenatal diagnosis.

Lethals, steriles and deficiencies in a region of the X chromosome of Caenorhabditis elegans

Twenty-one X-linked recessive lethal and sterile mutations balanced by an unlinked X-chromosome duplication have been identified following EMS treatment of the small nematode, Caenorhabditis elegans. The mutations have been assigned by complementation analysis to 14 genes, four of which have more than one mutant allele. Four mutants, all alleles, are temperature-sensitive embryonic lethals. Twelve mutants, in ten genes, are early larval lethals. Two mutants are late larval lethals, and the expression of one of these is influenced by the number of X chromosomes in the genotype. Two mutants are maternal-effect lethals; for both, oocytes made by mutant hermaphrodites are rescuable by wild-type sperm. One of the maternal-effect lethals and two larval lethals are allelic. One mutant makes defective sperm. The lethals and steriles have been mapped by recombination and by complementation testing against 19 deficiencies identified after X-ray treatment. The deficiencies divide the region, about 15% of the X-chromosome linkage map, into at least nine segments. The deficiencies have also been used to check the phenotypes of hemizygous lethal and sterile hermaphrodites.

Hybrid dysgenesis in Drosophila melanogaster: the biology of female and male sterility

High levels of female and male sterility were observed among the hybrids from one of the two reciprocal crosses between a wild strain of D. melanogaster known as pi2 and laboratory strains. The sterility, which is part of a common syndrome called hybrid dysgenesis, was found to be associated with the rudimentary condition of one or both of the ovaries or testes. All other tissues, including those of the reproductive system were normal, as were longevity and mating behavior. The morphological details of the sterility closely mimic the agametic condition occurring when germ cells are destroyed by irradiation or by the maternal-effect mutation, grandchildless. We suggest that sterility in hybrid dysgenesis is also caused by failure in the early development of germ cells. There is a thermo-sensitive period beginning at approximately the time of initiation of mitosis among primordial germ cells a few hours before the egg hatches and ending during the early larval stages. Our results suggest that hybrid dysgenesis, which also includes male recombination, mutation and other traits, may be limited to the germ line, and that each of the primordial germ cells develops, or fails to develop, independently of the others. This hypothesis is consistent with the observed frequencies of unilateral and bilateral sterility, with the shape of the thermosensitivity curves and with the fact that males are less often sterile than females. The features of this intraspecific hybrid sterility are found to resemble those seen in some interspecific Drosophila hybrids, especially those from the cross D. melanogaster X D. simulans.

Genetic causes and workup of male and female infertility. 1. Prenatal reproductive loss

Studies show that the greatest check on human reproduction occurs prenatally in apparently fertile couples. Most chromosomally abnormal embryos are aborted spontaneously. This paper, to be published in three parts, reviews the major known anatomic, functional, genetic, and environmental causes of infertility and reproductive wastage. The second and third parts, to appear in succeeding issues, are concerned with chromosome abnormalities and congenital malformations in the period from birth to adult life and with the diagnostic workup of infertile men and women.

Satellite DNAs in eukaryotes: a non-adaptive mechanism of speciation which originated with sexual reproduction?

Satellite DNAs may have originated during evolution at the same time as sexual reproduction in order to suppress crossingover between the 2 heterogametic sex chromosomes, and may have acquired a function of sterility barriers in hybrid species during evolution. This origin of satellite DNAs appears to be reflected in different stages of speciation: partial and total heterogametic sex hybrid sterility and full hybrid sterility might correspond to subspecies, semispecies and full species.

Accumulation of deleterious genes in a cage population of Drosophila melanogaster

Lethal and sterility mutations were accumulated in a cage population which was initiated with lethal- and sterility-free second chromosomes of D. melanogaster. It took about 2,000 days for the frequencies of these genes to reach equilibrium levels, i.e., 18% lethal and 9% male-sterile chromosomes. Two other cage populations which were initiated with random chromosomes sampled from natural populations and kept for more than eleven years in the laboratory showed 19-20% lethal content. The elimination rates of lethals by homozygosis in these populations were smaller than the mutation rate. By using NEI's formulae, the deleterious effect of a lethal gene in heterozygous condition (h) was estimated to be 0.035. The effective population number in the cage populations was estimated to be 1,000-2,900, while the actual population number was 3,500-7,800.

[Problem of the infertility of hybrids of the muscovy (Cairina moschata L.) and the domestic duck (Anas platyrhynchos domestica)]

Analysis of blood serum proteins electrophoretic spectra for perching and domestic ducks resulted in revealing interspecific differences of prealbumin and transferrin types showing incomplete identity of loci in analogous sites of some homologous chromosomes in the hybridizants. This confirms the genetic nature of sterility in this crossing combination hybrids whose blood serum proteins electrophoretic spectrum displays a complex hybrid phenotype.

Chromosome markers in Mus musculus: differences in C-banding between the subspecies M.m. musculus and M.m. molossinus

Quinacrine (Q-band) and centromeric heterochromatin (C-band) patterns of metaphase chromosomes of two subspecies of Mus musculus were compared. M.m. musculus (the laboratory mouse) and M.m. molossinus (a subspecies from Southeast Asia) had similar Q-band patterns along the length of the chromosomes, but differences were observed in the centromeric region of some chromosomes. The two subspecies had very different distributions of C-band material. Antibodies to 5-methyleytosine were bound to regions of the chromosome corresponding to the C-bands in each animal. These findings support the idea that satellite DNA, which is concentrated in the C-band region, changes more quickly than bulk DNA. The interfertility of these two subspecies permits the development of a musculus strain carrying normal marker chromosomes for genetic studies.

Association of pericentric inversion of chromosome 9 and reproductive failure in ten unrelated families

A pericentric inversion of chromosome 9 has been detected in 10 unrelated families. The break points are identical and the inversions involved the heterochromatic segment. The effects of inversion of chromosome 9 on different aspects of reproductive failure are discussed.

The effects of mutant p-alleles on the reproductive system in mice

Thep6H,p25H, andpbsalleles at the pink-eyed dilution locus in mice (Mus musculus) cause sterility in males and semi-fertility in females when homozygous, while thepd, pun, p, and + alleles do not reduce fertility. Pituitaries from sterile males had significantly lower proportions of gonadotropic cells than pituitaries from fertile males. Ovaries from semi-fertile females contained large numbers of developing follicles, but no corpora lutea or corpora hemorrhagica were found. The proportion of polyovular follicles in ovaries of semifertile females was abnormally high.

Pituitary gonadotropins appear to be reduced in the sterile genotypes although the lesion cannot be localized. Possible relationships between these and other pleiotropic effects of mutantp-alleles are discussed.

Meiosis in interspecific equine hybrids. I. The male mule (Equus asinus X E. caballus) and hinny (E. caballus X E. asinus)

A detailed investigation of meiosis in the male mule and hinny has been made. Although breakdown of spermatogenesis at the pachytene stage of meiotic pro-phase was observed in most germ cells of the two hybrids, a few mature spermatozoa were recovered from the ejaculate and epididymal flushings of the hinny.