Trends in taxonomy of Triatomini (Hemiptera, Reduviidae, Triatominae): reproductive compatibility reinforces the synonymization of Meccus Stål, 1859 with Triatoma Laporte, 1832

Background Meccus' taxonomy has been quite complex since the first species of this genus was described by Burmeister in 1835 as Conorhinus phyllosoma. In 1859 the species was transferred to the genus Meccus and in 1930 to Triatoma. However, in the twentieth century, the Meccus genus was revalidated (alteration corroborated by molecular studies) and, in the twenty-first century, through a comprehensive study including more sophisticated phylogenetic reconstruction methods, Meccus was again synonymous with Triatoma. Events of natural hybridization with production of fertile offspring have already been reported among sympatric species of the T. phyllosoma subcomplex, and experimental crosses demonstrated reproductive viability among practically all species of the T. phyllosoma subcomplex that were considered as belonging to the genus Meccus, as well as between these species and species of Triatoma. Based on the above, we carried out experimental crosses between T. longipennis (considered M. longipennis in some literature) and T. mopan (always considered as belonging to Triatoma) to evaluate the reproductive compatibility between species of the T. phyllosoma complex. In addition, we have grouped our results with information from the literature regarding crosses between species that were grouped in the genus Meccus with Triatoma, in order to discuss the importance of experimental crosses to confirm the generic reorganization of species. Results The crosses between T. mopan female and T. longipennis male resulted in viable offspring. The hatching of hybrids, even if only in one direction and/or at low frequency, demonstrates reproductive compatibility and homeology between the genomes of the parents. Conclusion Considering that intergeneric crosses usually do not result in viable offspring in Triatominae, the reproductive compatibility observed between the T. phyllosoma subcomplex species considered in the Meccus genus with species of the Triatoma genus shows that there is “intergeneric” genomic compatibility, which corroborates the generic reorganization of Meccus in Triatoma. Graphic Abstract

Interchromosomal insertion (11;2): analysis of segregation in 4 generation of the family and characterization of segmental monoand trisomy phenotype in offspring

Межхромосомная инсерция - редкий вариант сбалансированной перестройки, когда интерстициальный фрагмент одной хромосомы встраивается в другую негомологичную хромосому. Носители инсерций имеют нормальный фенотип и фертильность, но повышенный риск как спонтанных абортов (СА), так и рождения детей с хромосомным дисбалансом. Цель исследования: оценить сегрегацию хромосом у носителей межхромосомной инсерции ins(11;2)(q21;q31.1q32.3) для уточнения риска наследования потомством несбалансированного набора хромосом, провести анализ фенотипических проявлений при сегментных моно- и трисомии 2q31.1q32.3. Представлены клинико-цитогенетические данные носителей межхромосомной ins(11;2)(q21;q31.1q32.1) с длиной инсертированного фрагмента 0,8-0,9% гаплоидной длины аутосом. У 6 носителей зарегистрировано 15 беременностей, из которых 47% завершилось неблагополучным исходом: удельный вес СА составил 20%, в 1 случае диагностирована неразвивающаяся беременность (кариотип плода 46,XY), унаследованный дисбаланс установлен у 3 потомков. Распределение вариантов с кариотипами нормальный : сбалансированная инсерция : der(2) : der(11) составило 3:6:1:1, эмпирический риск образования зигот с хромосомным дисбалансом - 18% (2/11). Данные сравнительного анализа проявлений моносомии 2q31.1q32.1 (2 представленных родственника) и моносомии 2q31q33 (18 ранее описанных живорожденных пациентов) демонстрируют высокую степень фенотипического сходства. Фенотипические признаки у двух пациентов с der(2)ins(11;2) соответствуют симптомокомплексу, который рассматривается клинически очерченным синдромом моносомии 2q31q32. Наличие эктродактилии у 2 детей подтверждает связь порока с утратой генов, локализованных в сегменте 2q31.1. Результаты анализа репродуктивных исходов в представленной семье и описанных в литературе случаев демонстрируют возможность рождения потомства как с моно-, так и с трисомией 2q31q32, и позволяют оценивать риски повторного рождения детей с данными сегментными анеусомиями на уровне 30-40%, а вероятность СА - в 20-33%. У плода с трисомией 2q31.1q32.3 отмечены неспецифические признаки аутосомного дисбаланса. Микроцефалия, расщелина неба/губы и неба, эктродактилия являются основными диагностическими маркерами патологии плода, значимыми для пренатальной УЗ диагностики. Interchromosomal insertion is a rare balanced chromosomal rearrangement that occur when an interstitial segment of one chromosome is translocated into another non-homologous chromosome. Carriers of insertions display normal phenotype and fertility, but have an increased risks of spontaneous abortions (SA) and viable offspring with inherited chromosomal imbalance. The aim of study: to assess the interchromosomal ins(11;2)(q21;q31.1q32.3) segregation to determine the genetic risk of inheriting an unbalanced karyotype by the outcome; to analyze segmental mono- and trisomy 2q31.1q32.3 phenotypic manifestations.Family with reproductive failure history was investigated using a clinical, genealogical, ultrasound, cytogenetical (GTG-banding) and morphological methods. Risks of reproductive loss and aneusomic offspring birth were calculated. The outcome prognosis and prenatal diagnostics results were discussed. Clinical, cytogenetical and reproductive history data of carriers ins(11;2) (q21;q31.1q32.3) were presented. The size of insertional segment is about 0,8-0,9% haploid autosomal length (HAL). Outcomes of 15 pregnancies of 6 carriers were as follows: rate of miscarries - 20%, one miscarriage - fetus with karyotype 46,XY, 3 cases - chromosomal imbalance. The segregation ratio for normal:balanced:der(2):der(11) is 3:6:1:1; the empirical risk for forming aneuploid zygotes is 18% (2/11). Segmental monosomy 2q31.1q32.1 phenotypic features in 2 presented patients are similar with clinical signs of 18 previously reported live-born children with monosomy 2q31q33. Ectrodactyly in 2 our patients confirms association of malformation with 2q31.1 region loss. The presented and reported cases data illustrate a possibility of giving birth of offspring with segmental monosomy as well as trisomy 2q31q32, risk of viable offspring with inherited imbalance may be estimated as 30-40%, spontaneous abortions rate - 20-33%. Fetus with trisomy 2q31.1q32.3 showed unspecific signs of autosomal imbalance. Pattern of phenotypical features reported in 2 relatives with der(2)ins(11;2) correlates with clinically recognizable monosomy 2q31q32 syndrome. Microcephaly, cleft palate/cleft lip and palate, ectrodactyly are the main diagnostic markers of fetal pathology which can be identified using prenatal ultrasound investigation.

Studies on Mating Preference and Productivity in Drosophila ananassae and D. pallidosa and Their Hybrids

During speciation different kinds of reproductive barriers originate to preclude gene flow between diverging populations. Reproductive isolation or barriers to gene flow can be categorized by the temporal nature of their effect: pre-zygotic barriers occur before fertilization and post-zygotic barriers occur after fertilization. In this study, we studied each components of reproductive isolation between D. ananassae and D. pallidosa, including both pre-zygotic and post-zygotic barriers. Because it might be possible that by dissecting these barriers one can get the answers of many unresolved questions related to the process of speciation of these two sibling species. We reported premating isolation because females of both D. ananassae and D. pallidosa were more discriminative for mating against the alien males rather than conspecific males, and this discrimination was much stronger in case of D. ananassae females for being the ancestral and cosmopolitan species. We also did not find any decrease in the production of progeny or viable offspring in comparison to conspecific males, indicating a lack of postmating prezygotic isolating barriers. Further, there is no complete lack of intrinsic post-zygotic isolation between these species or not complete presence of post-zygotic isolation, as both the hybrid sons were producing less number of progeny in comparison to all the crosses but it is near to significant but not significant and this is contrasting to the results of a previous study.

Formation of reproductive organs of young livestock depending on paratypic factors

The study was conducted to identify the early use of young animals (gobies and heifers) in cattle for breeding purposes. The condition under which the research was carried out was intensive and traditional rearing of young cattle. In the experimental groups, feeding was intense, and in the control groups – according to the accepted technology in the farm. Young growth was carried out until the age of 15 months. Under such different growing conditions, we have established the features of the formation of reproductive organs in gobies and heifers. The good development of the genitals of the heifers of the experimental group, and especially the ovaries, made it possible to carry out their fruitful insemination in the period from 13 to 14 months of age. For this, two bulls were selected from the experimental group at the age of 12-13 months, which, by manual mating, inseminated 20 heifers for a month. During a rectal examination, they turned out to be all pregnant and in due time, without complications, became hotels, gave normal viable offspring. Calving calves aged 22-23 months during 1 lactation they were in no way inferior in milk production to heifers inseminated at the age of 24-28 months and calving at 33-37 months.

Investigation of the Guinea fowl and domestic fowl hybrids as potential surrogate hosts for avian cryopreservation programmes

In the last decade, avian gene preservation research has focused on the use of the early precursors of the reproductive cells, the primordial germ cells (PGCs). This is because avian PGCs have a unique migration route through the vascular system which offers easy accessibility. Furthermore, culturing of the cells in vitro, freezing/thawing, reintegration into a recipient embryo and the development of the germ cells can be carried out in well-defined laboratory circumstances. The efficient recovery of the donor genotype and the frequency of germline transmission from the surrogate host animals are still areas which need further development. Thus, the aim of the present study was to investigate an infertile interspecific hybrid (recipient) as an appropriate host for primordial germ cells from native poultry breeds. Guinea fowl × chicken hybrids were produced, the crossing was repeated inversely. The phenotype, the hatching time, the hatching rate, the sex ratio, the presence of own germ cells, the fertility and the phenotype of viable hybrids and the incidence of chromosomal abnormalities of dead hybrid embryos were described. 6.65% viable offspring was obtained with crossing of Guinea fowl females with domestic fowl males. Crossing of domestic fowl hens with Guinea fowl male resulted in lower fertility, 0.14% viable offspring. Based on the investigations, the observed offspring from the successful crossing were sterile male hybrids, thus an extreme form of Haldane’s rule was manifested. The sterile hybrid male embryos were tested by injecting fluorescently labeled chicken PGCs. The integration rate of labeled PGCs was measured in 7.5-day, 14.5-day and 18.5-day old embryonic gonads. 50%, 5.3% and 2.4% of the injected hybrid embryos survived and 40%, 5.3% and 2.4% of the examined gonads contained fluorescent labeled donor PGCs. Therefore, these sterile hybrid males may be suitable recipients for male PGCs and possibly for female PGCs although with lower efficiency. This research work shows that the sterility of hybrids can be used in gene conservation to be a universal host for PGCs of different avian species.

Haploinsufficient maternal effect of Epidermal Growth Factor Receptor A mutation in zebrafish

Generation of viable offspring depends both on genetic and environmental factors of both mother and child. Analysis of a likely amorphic allele of the zebrafish epidermal growth factor receptor a (egfra) gene revealed that heterozygous females were infertile due to death of all fertilized eggs during embryonic and early larval life with cardiac, tail and other defects. Comparison of the severe dominant maternal effect with previous studies using pharmacological inhibitors of Egfrs or antisense morpholino injection indicate that a normal level of maternal Egfra is required for viability of offspring both during egg development and in the embryo after fertilisation. As heterozygous mothers were not fertile, the homozygous zygotic egfrakg134 phenotype could not be analysed. Heterozygous egfra+/kg134 males crossed to wild type females produced fully viable offspring, among which egfra+/kg134 individuals had increased slow muscle but no functional motility defect. Our findings suggest that Egfra activity is crucial for early development both before and after fertilisation and are likely to constitute a rare example of a haploinsufficient maternal effect in a species lacking imprinting.

Conservation of chicken male germline by orthotopic transplantation of primordial germ cells from genetically distant donors†

Successful derivation and cultivation of primordial germ cells (PGCs) opened the way to efficient transgenesis and genome editing in the chicken. Furthermore, implantation of male PGCs from non-chicken galliform species into the chicken embryos resulted in cross-species germline chimeras and viable offspring. We have recently improved the PGC technology by demonstrating that chicken male PGCs transplanted into the testes of adult cockerel recipients mature into functional sperms. However, the availability of this orthotopic transplantation for cross-species transfer remains to be explored. Here we tested the capacity of genetically distant male PGCs to mature in the microenvironment of adult testes. We derived PGCs from the Chinese black-bone Silkie and transplanted them into infertile White Leghorn cockerels. Within 15–18 weeks after transplantation, we observed restoration of spermatogenesis in recipient cockerels and production of healthy progeny derived from the transplanted PGCs. Our findings also indicate the possibility of cross-species orthotopic transplantation of PGCs. Thus, our results might contribute to the preservation of endangered avian species and maintaining the genetic variability of the domestic chicken.

First empirical evidence of naturally occurring androgenesis in vertebrates

Androgenesis among vertebrates is considered a rare phenomenon, with some cases reported so far, but linked to experiments involving gamete manipulation (artificial androgenesis). Herein, we report the first empirical evidence of the natural occurrence of spontaneous androgenesis in a vertebrate, the Squalius alburnoides allopolyploid complex. A genetically screened random sample of a natural population was allowed to reproduce in an isolated pond without any human interference, and the viable offspring obtained was later analysed for paternity. Both nuclear and mitochondrial markers showed that the only allodiploid fish found among all the allotriploid offspring was androgenetically produced by an allodiploid male. This specimen had no female nuclear genomic input, and the sequence of the mitochondrial fragment examined differed from that of the male progenitor, matching one of the parental females available in the pond, probably the mother. The possible role of androgenesis in the reproductive dynamics of this highly successful vertebrate complex is discussed.