Meiosis in the human pathogen Aspergillus fumigatus has the highest known number of crossovers

Evidence from both population genetics and a laboratory sexual cycle indicate that sex is common in the fungus Aspergillus fumigatus. However, the impact of sexual reproduction has remained unclear. Here, we show that meiosis in A. fumigatus involves the highest known recombination rate, producing ~29 crossovers per chromosome. This represents the highest known crossover rate for any Eukaryotic species. We validate this recombination rate by mapping resistance to acriflavine, a common genetic marker. We further show that this recombination rate can produce the commonly encountered TR34/L98H azole-resistant cyp51A haplotype in each sexual event, facilitating its rapid and global spread. Understanding the consequences of this unparalleled crossover rate will not only enrich our genetic understanding of this emergent human pathogen, but of meiosis in general.

Stress conditions promote Leishmania hybridization in vitro marked by expression of the ancestral gamete fusogen HAP2 as revealed by single-cell RNAseq

Leishmania are protozoan parasites transmitted by the bite of sand fly vectors producing a wide spectrum of diseases in their mammalian hosts. These diverse clinical outcomes are directly associated with parasite strain and species diversity. Although Leishmania reproduction is mainly clonal, a cryptic sexual cycle capable of producing hybrid genotypes has been inferred from population genetic studies, and directly demonstrated by laboratory crosses. Experimentally, mating competence has been largely confined to promastigotes developing in the sand fly midgut. The ability to hybridize culture promastigotes in vitro has been limited so far to low efficiency crosses between two L. tropica strains, L747 and MA37, that mate with high efficiency in flies. Here, we show that exposure of promastigote cultures to DNA damage stress produces a remarkably enhanced efficiency of in vitro hybridization of the L. tropica strains, and extends to other species, including L. donovani, L. infantum, and L. braziliensis, a capacity to generate intra- and interspecific hybrids. Whole genome sequencing and total DNA content analyses indicate that the hybrids are in each case full genome, mostly tetraploid hybrids. Single-cell RNA sequencing of the L747 and MA37 parental lines highlights the transcriptome heterogeneity of culture promastigotes and reveals discrete clusters that emerge post-irradiation in which genes potentially involved in genetic exchange are expressed, including the ancestral gamete fusogen HAP2. By generating reporter constructs for HAP2, we could select for promastigotes that could either hybridize or not in vitro. Overall, this work reveals that there are specific populations involved in Leishmania hybridization associated with a discernible transcriptomic signature, and that stress facilitated in vitro hybridization can be a transformative approach to generate large numbers of hybrid genotypes between diverse species and strains.

Ihtiofauna lacului de acumulare Dubăsari – compoziția, dinamica modificărilor stării cantitative și calitative

This paper represents the results of the researches of the ichthyofauna of the Dubăsari accumulation lake in successional aspect. It was found that due to the influence of anthropogenic factors in the last 5-6 decades (construction of Naslavcea and Novodnestrovsc dams, excavation of sand and river gravel from the minor riverbed, use of water for various purposes, accidental, biological and thermal pollution, damage and destruction of substrate of reproduction for lithophilic and phytophilic species, etc.) in the ichthyofauna of the middle course of the Dniester River (Naslavcea – Camenca village) and the Dubasari accumulation lake have undergone essential changes, reflecting the structural and functional status of the fish populations, the growth rate, sexual maturation, prolificacy and the annual sexual cycle. Apart from these factors that have influenced and continue to negatively influence the fishery resources in the Dubasari reservoir, the factor of their poor management also persists in the last 25 years.

Genetic Networks That Govern Sexual Reproduction in the Pezizomycotina

Sexual development in filamentous fungi is a complex process that relies on the precise control of and interaction between a variety of genetic networks and pathways. The mating-type ( MAT ) genes are the master regulators of this process and typically act as transcription factors, which control the expression of genes involved all stages of the sexual cycle.

Alpha/Beta Hydrolase Domain-Containing Protein 2 Regulates the Rhythm of Follicular Maturation and Estrous Stages of the Female Reproductive Cycle

Mammalian female fertility is defined by a successful and strictly periodic ovarian cycle, which is under the control of gonadotropins and steroid hormones, particularly progesterone and estrogen. The latter two are produced by the ovaries that are engaged in controlled follicular growth, maturation, and release of the eggs, i.e., ovulation. The steroid hormones regulate ovarian cycles via genomic signaling, by altering gene transcription and protein synthesis. However, despite this well-studied mechanism, steroid hormones can also signal via direct, non-genomic action, by binding to their membrane receptors. Here we show, that the recently discovered membrane progesterone receptor α/β hydrolase domain-containing protein 2 (ABHD2) is highly expressed in mammalian ovaries where the protein plays a novel regulatory role in follicle maturation and the sexual cycle of females. Ablation of Abhd2 caused a dysregulation of the estrous cycle rhythm with females showing shortened luteal stages while remaining in the estrus stage for a longer time. Interestingly, the ovaries of Abhd2 knockout (KO) females resemble polycystic ovary morphology (PCOM) with a high number of atretic antral follicles that could be rescued with injection of gonadotropins. Such a procedure also allowed Abhd2 KO females to ovulate a significantly increased number of mature and fertile eggs in comparison with their wild-type littermates. These results suggest a novel regulatory role of ABHD2 as an important factor in non-genomic steroid regulation of the female reproductive cycle.

Reproductive Potential of Stone Moroko (Pseudorasbora parva, Temminck et Schlegel, 1846) (Teleostei: Cypriniformes: Gobionidae) Inhabiting Central Europe

Similar to other invasive species, stone moroko is extending its global distribution. The present study aimed to assess the reproductive potential of stone moroko fish in a new habitat in Poland based on analysing the sexual cycle and fecundity. Fish morphometric data, age, and gonadal structures were analysed. Fish age ranged from 0+ to 5+ years. Most females and males (93% and 60%, respectively) had reached sexual maturity in the first year of their life, with the smallest length of 25 mm and 28 mm, respectively. The mean, standard length of the body was 50 mm. The spawning season was spread over four months from late-April to mid-August. Females laid eggs in portions, and the absolute and relative fecundity was 1372 and 1691, respectively. Stone moroko males were ready to spawn for a longer time period than females. The present study shows greater reproductive potential of stone moroko population in the central Europe than the native population, suggesting its successful colonisation in the new habitat.

Stress conditions promote the mating competency of Leishmania promastigotes in vitro marked by expression of the ancestral gamete fusogen HAP2

Leishmania are protozoan parasites transmitted by the bite of sand fly vectors producing a wide spectrum of diseases in their mammalian hosts. These diverse clinical outcomes are directly associated with parasite strain and species diversity. Although Leishmania reproduction is mainly clonal, a cryptic sexual cycle capable of producing hybrid genotypes has been inferred from population genetic studies, and directly demonstrated by laboratory crosses. Experimentally, mating competency has been largely confined to promastigotes developing in the sand fly midgut. The ability to hybridize culture promastigotes in vitro has been limited so far to low efficiency mating between two L. tropica strains, L747 and MA37, that mate with high efficiency in flies. Here, we show that exposure of promastigote cultures to DNA damage stress produces a remarkably enhanced efficiency of in vitro hybridization of the L. tropica strains, and extends to other species, including L. donovani, L. infantum, and L. braziliensis, a capacity to generate intra- and interspecific hybrids. Whole genome sequencing and total DNA content analyses indicate that the hybrids are in each case full genome, polyploid hybrids. Single-cell RNA sequencing of the L747 and MA37 parental lines highlights the transcriptome heterogeneity of culture promastigotes and reveals discrete clusters that emerge post-irradiation in which genes potentially involved in genetic exchange are expressed, including the ancestral gamete fusogen HAP2. By generating reporter constructs for HAP2, we could select for mating-competent and mating-incompetent promastigotes. Overall, this work reveals that there are specific populations involved in Leishmania mating associated with a discernible transcriptomic signature, and that stress facilitated in vitro hybridization can be a transformative approach to generate large numbers of hybrid genotypes between diverse species and strains.

Influence of sexual cycle phases on cognitive abilities and physical endurance

We researched the dependence of cognitive abilities, mostly connected to functions of right and left hemispheres, and physical endurance on phases of sexual cycle. We discovered that on the first day of the cycle the number of correct tasks, connected with functions of the right hemisphere, was bigger than in the middle of the cycle, while no difference was detected in tasks, connected with functions of the left hemisphere. In the beginning of the cycle all test subjects correctly answered more "right hemisphere" questions, than during the ovulation phase, in the middle of the cycle the majority of test subjects correctly answered more "left hemisphere" tasks. We assume that sexual steroids moderate functional differences, connected with functions of right and left hemisphere. Precisely, low level of sexual steroids in the beginning of the cycle helps to activate functions of the right hemisphere, while steroids concentration in the middle of the cycle stops those functions. The level of heartbeat under the physical load was bigger in the luteal phase than before the ovulation; with the increase of load the heartbeat decreased before the ovulation and increase in the luteal phase. We assume that increased content of estrogens before the ovulations lead to decrease in physical endurance, while the decrease of concentration of estrogens in the luteal phase increased this endurance. Therefore, influence of sexual steroids helps to activate functions, which characterize specific psychological and physical status of women sex, particularly verbal abilities, lower abilities for visual analysis, and lower physical endurance of women.

Short homology-directed repair using optimized Cas9 in the pathogen Cryptococcus neoformans enables rapid gene deletion and tagging

Cryptococcus neoformans, the most common cause of fungal meningitis, is a basidiomycete haploid budding yeast with a complete sexual cycle. Genome modification by homologous recombination is feasible using biolistic transformation and long homology arms, but the method is arduous and unreliable. Recently, multiple groups have reported the use of CRISPR-Cas9 as an alternative to biolistics, but long homology arms are still necessary, limiting the utility of this method. Since the S. pyogenes Cas9 derivatives used in prior studies were not optimized for expression in C. neoformans, we designed, synthesized, and tested a fully C. neoformans-optimized Cas9. We found that a Cas9 harboring only common C. neoformans codons and a consensus C. neoformans intron together with a TEF1 promoter and terminator and a nuclear localization signal (C. neoformans-optimized CAS9 or 'CnoCAS9') reliably enabled genome editing in the widely-used KN99α C. neoformans strain. Furthermore, editing was accomplished using donors harboring short (50 bp) homology arms attached to marker DNAs produced with synthetic oligonucleotides and PCR amplification. We also demonstrated that prior stable integration of CnoCAS9 further enhances both transformation and homologous recombination efficiency; importantly, this manipulation does not impact virulence in animals. We also implemented a universal tagging module harboring a codon-optimized fluorescent protein (mNeonGreen) and a tandem Calmodulin Binding Peptide-2X FLAG Tag that allows for both localization and purification studies of proteins for which the corresponding genes are modified by short homology-directed recombination. These tools enable short-homology genome engineering in C. neoformans.