Impacts of male chromosomal polymorphisms on semen quality and IVF/ICSI outcomes: A retrospective cohort study

OBJECTIVE

The study aims to elucidate the impacts of different types of male chromosomal polymorphisms (MCPs) on various outcomes of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) treatment.

METHODS

This retrospective cohort study included 1442 couples with normal karyotypes, 1442 couples with MCPs, 42 couples with male chromosomal rearrangements (MCRs), and 42 couples with MCRs combined with MCPs who underwent IVF/ICSI treatment at Peking University Third Hospital from 2015 to 2021. The semen quality, embryological outcomes, and clinical outcomes of different groups stratified by karyotypes were compared.

RESULTS

For couples undergoing IVF, male inv(9) was associated with a significantly lower sperm viability rate (29.41% vs 34.49%, P = 0.030), a lower progressive motility rate (25.13% vs 30.50%, P = 0.013), and a lower normal fertilization rate (52.41% vs 59.84%, P = 0.014). Male 9qh + was related to a lower sperm viability rate (27.56% vs 34.49%, P = 0.028). No MCPs were observed to compromise clinical outcomes in couples undergoing IVF. For couples undergoing ICSI, no MCPs exhibited an association with poorer semen quality and embryological outcomes. However, Yqh + and DGpstk+ were found to be significantly correlated with an increased likelihood of preterm birth (23.3% vs 9.2%, P = 0.003; 20.0% vs 9.2%, P = 0.041, respectively). In couples with MCRs, the presence of MCPs significantly reduced the sperm viability rate (19.99% vs 30.97%, P = 0.017) and progressive motility rate (8.07% vs 27.85%, P = 0.018).

CONCLUSION

Our study provides detailed evidence for the impacts of various MCPs on IVF/ICSI outcomes, reveals the complexity and heterogeneity of these impacts, and highlights the adverse effects of male inv(9).

Cranial morphological variation of Ctenomys lami (Rodentia: Ctenomyidae) in a restricted geographical distribution

The relationship between chromosomal and morphological variation in mammals is poorly understood. We analyzed the cranial size and shape variation in Ctenomys lami concerning to the geographic variation in their chromosome numbers. This subterranean rodent occurs in a narrow range of sand-dunes in the Coastal Plain of southern Brazil. This species presents a high karyotypic variation with diploid numbers varying from 2n = 54 to 2n = 58, involving the fission and fusion of chromosome pairs 1 and 2. Due to different chromosome rearrangement frequencies along their geographic distribution, four karyotypic blocks were proposed. This study, explored cranium shape and size variation in geographical, chromosomal polymorphism, and chromosome rearrangements contexts to test whether the four karyotypic blocks reflect morphologically distinct units. For this, we measured 89 craniums using geometric morphometrics and used uni and multivariate statistics to discriminate the predicted groups and test for an association among chromosomal and morphological variation. Our results show the size and shape of sexual dimorphism, with males larger than females, and support the existence of four karyotypic blocks for Ctenomys lami based on morphological variation. However, our results do not support a direct relationship between chromosomal and cranial morphological variation in C. lami.

Chromosome Asynapsis Is the Main Cause of Male Sterility in the Interspecies Hybrids of East Asian Voles (Alexandromys, Rodentia, Arvicolinae)

Closely related mammalian species often have differences in chromosome number and morphology, but there is still a debate about how these differences relate to reproductive isolation. To study the role of chromosome rearrangements in speciation, we used the gray voles in the Alexandromys genus as a model. These voles have a high level of chromosome polymorphism and substantial karyotypic divergence. We investigated testis histology and meiotic chromosome behavior in the captive-bred colonies of Alexandromys maximowiczii, Alexandromys mujanensis, two chromosome races of Alexandromys evoronensis, and their interracial and interspecies hybrids, to explore the relationship between karyotypic differences and male hybrid sterility. We found that the seminiferous tubules of the males of the parental species and the interracial hybrids, which were simple heterozygotes for one or more chromosome rearrangements, contained germ cells at all stages of spermatogenesis, indicating their potential fertility. Their meiotic cells displayed orderly chromosome synapsis and recombination. In contrast, all interspecies male hybrids, which were complex heterozygotes for a series of chromosome rearrangements, showed signs of complete sterility. Their spermatogenesis was mainly arrested at the zygotene- or pachytene-like stages due to the formation of complex multivalent chains, which caused extended chromosome asynapsis. The asynapsis led to the silencing of unsynapsed chromatin. We suggest that chromosome asynapsis is the main cause of meiotic arrest and male sterility in the interspecies hybrids of East Asian voles.

The Influence of Chromosomal Polymorphism on Embryo Development and Embryonic Molecular Karyotype in Preimplantation Genetic Testing for Chromosomal Translocation

Traditionally, chromosomal polymorphisms (CPMs) are normal genetic variants in individuals with no phenotypic variations. However, some studies have shown that CPM is related to reproductive diseases. We explored the influence of CPM on embryonic development and molecular karyotype in chromosomal translocation (CT) patients undergoing preimplantation genetic testing (PGT) between February 2013 and May 2019. Twenty-six cases with CPM and 56 controls with normal chromosomes were included. Furthermore, a 1:4 match pair analysis by female age included 39 cases with CTCPM and 185 controls with CT. There was no statistical difference in fertilization rate (78.48% vs. 78.33%), cleavage rate on Day 3 (90.32% vs. 89.16%), blastocyst rate (60.00% vs. 60.80%), and the high-quality blastocyst rate (36.31% vs. 35.22%) between CPM and normal chromosomes. The high-quality blastocyst rate of CTCPM was significantly lower than that for CT (26.78% vs. 38.89%). Moreover, there was no statistical difference in fertilization rate (70.65% vs. 70.37%), cleavage rate on Day 3 (88.67% vs. 89.53%), and blastocyst rate (48.48% vs. 53.17%) between CTCPM and CT. In addition, one CTCPM spouse had a lower high-quality blastocyst rate, especially of males with CTCPM. Abnormal embryo rates of CTCPM were significantly higher than those for CT (78.64% vs. 68.93%). Abnormal embryo rates were higher in both CTCPM and CPM paternal carriers with CT partners, respectively. For CT, CTCPM may have an impact on the high-quality blastocyst rate and embryonic molecular karyotype, especially in male patients. Patients with CTCPM are relatively rare, but this population would benefit from being explored using a larger sample size.

[Chromosomal polymorphisms are associated with blastomere multinucleation in IVF/ICSI cycles]

OBJECTIVE

To investigate the association of chromosomal polymorphisms with multinucleated embryos in infertile couples undergoing in vitro fertilization-intracytoplasmic sperm injection (IVF-ICSI).

METHODS

This retrospective case-control study was conducted among 1145 infertile couples undergoing their first IVF/ICSI cycles. According to their karyotype, the couples were divided into chromosomal polymorphism group and control group, and the former group was divided into 3 subgroups: inversion group, D and G genome polymorphic group and 1, 9, and 16 qh+group. The blastomere multinucleation rate, clinical pregnancy rate and live birth rate were compared between the groups.

RESULTS

Of the total of 1145 couples, 139 (6.10%) had chromosomal polymorphisms at least in one partner. No significant differences were found in female age, BMI, basal FSH level, total gonadotropin dose, E₂ level on day of HCG, number of oocytes retrieved, fertilization rate, top quality embryo rate, clinical pregnancy rate or live birth rate among the groups (P > 0.05). The multinuclear rate of the embryos in couples with pericentric inversion of chromosomes 1, 9, and Y chromosomes and those with D and G genome polymorphisms were 8.23% and 4.65%, respectively, significantly higher than that in the control group (2.69%; P < 0.05); the multinuclear rate of the embryos was 2.77% in 1, 9, and 16 qh+ group, similar with that in the control group (P > 0.05).

CONCLUSIONS

Infertile couples with pericentric inversion of chromosomes 1, 9, and Y chromosomes and in those with D and G genome polymorphism are at higher risks of blastomere multinucleation in IVF- ICSI cycles; 1, 9, and 16 qh + polymorphisms do not increase the rate of blastomere multinucleation of the embryos.

Chromosomal Differentiation in Genetically Isolated Populations of the Marsh-Specialist Crocidura suaveolens (Mammalia: Soricidae)

The genus Crocidura represents a remarkable model for the study of chromosome evolution. This is the case of the lesser white-toothed shrew (Crocidura suaveolens), a representative of the Palearctic group. Although continuously distributed from Siberia to Central Europe, C. suaveolens is a rare, habitat-specialist species in the southwesternmost limit of its distributional range, in the Gulf of Cádiz (Iberian Peninsula). In this area, C. suaveolens is restricted to genetically isolated populations associated to the tidal marches of five rivers (Guadiana, Piedras, Odiel, Tinto and Guadalquivir). This particular distributional range provides a unique opportunity to investigate whether genetic differentiation and habitat specialization was accompanied by chromosomal variation. In this context, the main objective of this study was to determinate the chromosomal characteristics of the habitat-specialist C. suaveolens in Southwestern Iberia, as a way to understand the evolutionary history of this species in the Iberian Peninsula. A total of 41 individuals from six different populations across the Gulf of Cádiz were collected and cytogenetically characterized. We detected four different karyotypes, with diploid numbers (2n) ranging from 2n = 40 to 2n = 43. Two of them (2n = 41 and 2n = 43) were characterized by the presence of B-chromosomes. The analysis of karyotype distribution across lineages and populations revealed an association between mtDNA population divergence and chromosomal differentiation. C. suaveolens populations in the Gulf of Cádiz provide a rare example of true karyotypic polymorphism potentially associated to genetic isolation and habitat specialization in which to investigate the evolutionary significance of chromosomal variation in mammals and their contribution to phenotypic and ecological divergence.

Constitutive heterochromatin heteromorphism in the Neotropical armored catfish Hypostomusregani (Ihering, 1905) (Loricariidae, Hypostominae) from the Paraguay River basin (Mato Grosso do Sul, Brazil)

A cytogenetic analysis based on the integration of a number of different chromosomal methodologies, including chromosome microdissection was carried out to characterize the chromosomally polymorphic Hypostomusregani population from the Paraguay River basin, state of Mato Grosso do Sul in Brazil. All specimens had 2n=72 (FN=116) but two distinct karyotype formulas: karyomorph A (12m+14sm+18s+28a) and karyomorph B (13m+14sm+17st+28a). Karyomorph A and B differed only for pair 19 that consisted of two subtelocentrics in karyomorph A and a large metacentric and a subtelocentric in karyomorph B. This heteromorphism was due to extensive heterochromatinization of the short arm of the large metacentric, as highlighted by C-banding. The microdissection of the large metacentric of pair 19 allowed the production of a probe, named HrV (Hypostomusregani Variant), that hybridized to the whole p arm of the large metacentric and the pericentromeric region of the short arm of its (subtelocentric) homologue (karyomorph B) and of both homologs of pair 19 in karyomorph A. Additional cytogenetic techniques (FISH with 18S and 5S rDNA probes, CMA₃ and DAPI staining) allowed a finer distinction of the two karyomorphs. These results reinforced the hypothesis that the novel large metacentric of H.regani (karyomorph B) was the result of the amplification of heterochromatin segments, which contributed to karyotypic diversification in this species.

Chromosomal polymorphisms are associated with female infertility and adverse reproductive outcomes after infertility treatment: a 7-year retrospective study

Data from 19,950 women were retrospectively analysed to determine the effect of chromosomal polymorphisms on female infertility and pregnancy outcome; fertile women were used as controls. Frequency of chromosomal polymorphisms and adverse pregnancy outcomes were compared between groups. A significantly higher incidence of chromosomal polymorphisms was found in total infertile patients, and patients with tubal infertility, ovulatory dysfunction, cervical and uterine abnormalities, and unexplained infertility compared with controls (5.53% [P < 0.001], 4.86% [P = 0.012] 5.40% [P < 0.001], 5.75% [P < 0.001] and 8.51% [P < 0.001], versus 3.74%, respectively). Infertile women had a higher incidence of 9qh+ and inv(9) compared with controls (P < 0.001 and P = 0.027). Logistic regression analysis showed an effect of chromosomal polymorphisms on female infertility (adjusted OR 1.662, 95% CI 1.551 to 1.796, P < 0.001). All couples reported a phenotypically normal baby. In control and tubal infertility groups, miscarriage rates were higher in women with chromosomal polymorphisms than in women with normal chromosomes (4.95% versus 0.96%, P = 0.001 and 6.17% versus 1.08%, P < 0.001). Preterm birth rate showed a similar trend. Chromosomal polymorphisms adversely affected spontaneous miscarriage rates (adjusted OR 1.625, 95% CI 1.514 to 1.769, P = 0.005).

New Oligonucleotide Probes for ND-FISH Analysis to Identify Barley Chromosomes and to Investigate Polymorphisms of Wheat Chromosomes

Oligonucleotide probes that can be used for non-denaturing fluorescence in situ hybridization (ND-FISH) analysis are convenient tools for identifying chromosomes of wheat (Triticum aestivum L.) and its relatives. New oligonucleotide probes, Oligo-HvT01, Oligo-pTa71-1, Oligo-s120.1, Oligo-s120.2, Oligo-s120.3, Oligo-275.1, Oligo-275.2, Oligo-k566 and Oligo-713, were designed based on the repetitive sequences HVT01, pTa71, pTa-s120, pTa-275, pTa-k566 and pTa-713. All these probes can be used for ND-FISH analysis and some of them can be used to detect polymorphisms of wheat chromosomes. Probes Oligo-HvT01, Oligo-pTa71-1, Oligo-s120.3, Oligo-275.1, Oligo-k566 and Oligo-713 can, respectively, replace the roles of their original sequences to identify chromosomes of some barley (Hordeum vulgare ssp. vulgare) and the common wheat variety Chinese Spring. Oligo-s120.1, Oligo-s120.2 and Oligo-275.2 produced different hybridization patterns from the ones generated by their original sequences. In addition, Oligo-s120.1, Oligo-s120.2 and Oligo-s120.3, which were derived from pTa-s120, revealed different signal patterns. Likewise, Oligo-275.1 and Oligo-275.2, which were derived from pTa-275, also displayed different hybridization patterns. These results imply that differently arranged or altered structural statuses of tandem repeats might exist on different chromosome regions. These new oligonucleotide probes provide extra convenience for identifying some wheat and barley chromosomes, and they can display polymorphisms of wheat chromosomes.

Karyotype characteristics, larval morphology and chromosomal polymorphism peculiarities of Glyptotendipes salinus Michailova, 1983 (Diptera, Chironomidae) from Tambukan Lake, Central Caucasus

Data on the karyotype characteristics, larval morphology and features of chromosomal polymorphism of a population of Glyptotendipes salinus Michailova, 1983 (Diptera, Chironomidae) from Tambukan Lake (on the northern macroslope of the central Caucasus) are presented. It was found that diagnostic larval characters of Glyptotendipes salinus from Caucasus in general are similar to those described in previous studies, but with some significant differences. By some morphological characteristics Caucasian larvae appeared to be closer to Glyptotendipes barbipes than to ones provided for European larvae of Glyptotendipes salinus by Contreras-Lichtenberg (1999). Obtained morphological data make possible to conclude that Caucasian population of Glyptotendipes salinus can be a markedly diverged population of the species, probably even subspecies. In the Caucasian population 12 banding sequences were found: two in arms A, B, C, E, and G, and one in arms D and F. Eight of these are already known for this species, and four, salA2, salB2, salEX, and salG3, are described for the first time. Genetic distances between all the previously studied populations of Glyptotendipes salinus were measured using Nei criteria (1972). The population of the central Caucasus occupies a distinct position on the dendrogram compared with populations from Altai and Kazakhstan. All the obtained morphological and cytogenetic data can indicate the plausible relative isolation and complexity of the Caucasus from the viewpoint of microevolution. More researches are required in other parts of Caucasus and other geographically distant regions for more specific allegations.

Chromosome analysis of Endochironomus albipennis Meigen, 1830 and morphologically similar Endochironomus sp. (Diptera, Chironomidae) from water bodies of the Volga region, Russia

Based upon the detailed chromosome map of polytene chromosomes of the eurybiont species Endochironomus albipennis Meigen, 1830, the localization of the centromere regions using a C-banding technique is defined. Chromosomal polymorphism in populations from two water bodies in the Volga region has been studied, 17 sequences are described. Polytene chromosomes of Endochironomus sp. (2n=6), having larvae morphologically similar to those of Endochironomus albipennis Meigen, 1830 (2n=6) are described for the first time.

Effect of chromosomal polymorphisms of different genders on fertilization rate of fresh IVF-ICSI embryo transfer cycles

To explore whether chromosomal polymorphisms of different genders affect outcomes of fresh IVF and intracytoplasmic sperm injection (ICSI) embryo transfer cycles differently, 37 couples with chromosomal polymorphisms were identified out of 614 infertile couples undergoing IVF-ICSI treatments. Group 1 included 20 couples in which only the male carried chromosomal polymorphisms; group 2 included 17 couples with female carriers only; group 3 included 19 infertile couples with normal karyotypes randomly selected as controls. A significantly lower fertilization rate was found in group 1 compared with groups 2 and 3 (56.68% in Group 1, 78.02% in group 2 and 71.74% in group 3; group 1 versus group 2, P < 0.001; group 1 versus group 3, P = 0.001; respectively). When stratified according to fertilization method, the fertilization rate in IVF cycles of group 1 was significantly lower than group 3 (50.00% in Group 1, 73.89% in Group 3, P < 0.001). Fertilization rates in ICSI cycles between groups 1 and 3 were not significantly different. This study suggests that male chromosomal polymorphisms adversely influence fertilization rates of IVF cycles. The use of ICSI may improve the success of infertility treatment by increasing the fertilization rate for men with chromosomal polymorphisms.

The role of chromosome variation in the speciation of the red brocket deer complex: the study of reproductive isolation in females

BACKGROUND

The red brocket deer, Mazama americana, has at least six distinct karyotypes in different regions of South America that suggest the existence of various species that are today all referred to as M. americana. From an evolutionary perspective, the red brockets are a relatively recent clade that has gone through intense diversification. This study sought to prove the existence of post-zygotic reproductive isolation in deer offspring between distinct chromosome lineages. To achieve this, inter-cytotype and intra-cytotype crosses were performed, which resulted in both F1 hybrid (n = 5) and pure offspring (n = 3) in captivity.

RESULTS

F1 females were analyzed in terms of their karyotypes, ovarian histology, estrous cycles and in vitro embryo production. Pure females presented parameters that were similar to those previously reported for M. Americana; however, the parameters for hybrid females were different. Two hybrids were determined to be sterile, while the remaining hybrids presented characteristics of subfertility.

CONCLUSIONS

The results support the existence of well-established reproductive isolation among the most distant karyotype lineages and elucidates the need to define all karyotype variants and their geographical ranges in order to define the number of species of red brocket.

Karyotypes of Chironomus Meigen (Diptera: Chironomidae) species from Africa

The karyotypes of six African Chironomus species (Chironomus alluaudi Kieffer, 1913, Chironomus transvaalensis Kieffer, 1923, Chironomus sp. Nakuru, Chironomus formosipennis Kieffer, 1908, Chironomus prope pulcher Wiedemann, 1830, Chironomus sp. Kisumu) were investigated; four of these karyotypes were described for the first time (Chironomus sp. Nakuru, Chironomus formosipennis, Chironomus prope pulcher, Chironomus sp. Kisumu). Of the six Chironomus karyotypes, three had "pseudothummi" cytocomplex chromosome arms combinations AE CD BF G (Chironomus alluaudi, Chironomus transvaalensis, Chironomus sp. Nakuru), two had "thummi"cytocomplex arms combinations AB CD EF G (Chironomus formosipennis, Chironomus prope pulcher), and one had "parathummi"armcombinations AC BF DE G (Chironomus sp. Kisumu). Thus, three of the ten main cytocomplexes known were detected in Africa. Detailed photomaps of all chromosome arms, with the exception of arms B and G, were prepared for the karyotypes of Chironomus alluaudi, Chironomus transvaalensis, Chironomus sp. Nakuru, Chironomus prope pulcher; the karyotypes of Chironomus formosipennis, Chironomus sp. Kisumucould only be fragmentarily mapped. Endemic African banding sequences were characteristic for most of the chromosomal arms in all species studied. However, basic sequences, which can be present in different Chironomus species on different continents (Wülker, 1980; Kiknadze et al. 2008), were also detected also in several African species (Chironomus alluaudi, Chironomus sp. Nakuru, and Chironomus formosipennis). The banding sequences of African species studied allow discussion of the derivation of modern banding patterns from hypothetical species, living before separation of cytocomplexes and continents.

Tsetse genetics: contributions to biology, systematics, and control of tsetse flies

Tsetse flies (Diptera: Glossinidae) constitute a small, ancient taxon of exclusively hematophagous insects that reproduce slowly and viviparously. Because tsetse flies are the only vectors of pathogenic African trypanosomes, they are a potent and constant threat to humans and livestock over much of sub-Saharan Africa. Despite their low fecundity, tsetse flies demonstrate great resilience, which makes population suppression expensive, transient, and beyond the capacities of private and public sectors to accomplish, except over small areas. Nevertheless, control measures that include genetic methods are under consideration at national and supranational levels. There is a pressing need for sufficient laboratory cultures of tsetse flies and financial support to carry out genetic research. Here we review tsetse genetics from organismal and population points of view and identify some research needs.

Chromosomal control of mating activity in Drosophila pseudoobscura

Lines containing two third-chromosome inversions (Arrowhead and Pikes Peak) of Drosophila pseudoobscura selected for fast and slow mating speed were crossed to a multichromosomal, dominant marker inversion stock, and strains with various combinations of chromosomal derivation were tested for their mating activity. When lines were selected isodirectionally with the known third-chromosome control, the third chromosome was found to possess major epistatic control over mating speed, followed by the fourth, with no appreciable effect from the first and second. However, polygenic modification mating activity was found throughout the genome when selection was applied opposite to the original third-chromosome control. The work reported here strengthens the evidence that the adaptive role of chromosomal polymorphism has a behavioral basis in mating activity.