Nuclear retention of pre-mRNA involving Cajal bodies during meiotic prophase in plants

Gene regulation ensures that the appropriate genes are expressed at the proper times. Nuclear retention of incompletely spliced or mature mRNAs emerges as a novel, previously underappreciated layer of post-transcriptional gene regulation. Studies on this phenomenon indicated that it exerted significant impact on the regulation of gene expression by regulating export and translation delay, which allows synthesis of specific proteins in response to a stimulus, e.g. under stress conditions or at strictly controlled time points, e.g. during cell differentiation or development. Here, we found that transcription in microsporocytes, during prophase of the first meiotic division, occurs in pulsatile manner. After each pulse, the transcriptional activity is silenced, but the transcripts synthesized at this time are not exported immediately to the cytoplasm, but are retained in the nucleoplasm and Cajal bodies (CBs). In contrast to nucleoplasm, mature transcripts were not found in CBs. Only non-fully-spliced transcripts with retained introns were stored in the CBs. Retained introns are spliced at precisely defined times, and fully mature mRNAs are released into the cytoplasm, where the proteins are produced. These proteins are necessary for further cell development during meiotic prophase. Our findings provide new insight into the regulatory mechanisms of gene expression based on mRNA retention in the nucleus during the development of generative cells in plants. Similar processes were observed during spermatogenesis in animals. This indicates the existence of an evolutionarily conserved mechanism of gene expression regulation during generative cells development in Eukaryota.

Isolation of male and female gametes, zygotes and proembryos of leek (Allium tuberosum Roxb)

SummaryThe isolation of male and female gametes is an effective method to study the fertilization mechanisms of higher plants. An osmotic shock method was used to rupture pollen grains of Allium tuberosum Roxb and release the pollen contents, including generative cells, which were mass collected. The pollinated styles were cut following 3 h of in vivo growth, and cultured in medium for 6–8 h, during which time pollen tubes grew out of the cut end of the style. After pollen tubes were transferred into a solution containing 6% mannitol, tubes burst and released pairs of sperm cells. Ovules of A. tuberosum were incubated in an enzyme solution for 30 min, and then dissected to remove the integuments. Following transfer to a dissecting solution free of enzymes, each nucellus was cut in the middle, and squeezed gently on the micropylar end, resulting in the liberation of the egg, zygote and proembryo from ovules at selected stages. These cells can be used to explore fertilization and embryonic development using molecular biological methods for each cell type and development stage.

PSXIII-1 Age-related changes in the ratio of different spermatogonia types in the seminiferous tubules of quail testes

Spermatogonia are early-undifferentiated germ cells, giving rise to mature male generative cells — the spermatozoa. There are two types of spermatogonia – A and B. Of greatest interest is the use of type A spermatogonia, which are the stem cells of the testes. To select the appropriate age for collecting spermatogonia А from quails it is necessary to know the specific features of spermatogenesis. Development dynamics of various spermatogonia types in the quail testicular tubules was studied. Histological studies of the quails testicular tubules at the age of 1, 2, 3, 4, 5 and 6 weeks (n = 30) were carried out. Samples of testis tissue were fixed in Bouin’s fixative. Histological sections were stained with hematoxylin-eosin. Identification of different spermatogonia types was carried out according to their morphology. Type A spermatogonia were additionally identified by immunohistochemistry using SSEA-1 antibodies. The proportion of spermatogonia in the total number of spermatogenic cells in the seminiferous tubules of quails changed with age. The maximum value was reached at the age of 3 weeks and it was 76±6%. On reaching maturity (6 weeks), this indicator decreased to 12 ± 1 %. In the early period of ontogenesis (1–2 weeks), spermatogonia cells were represented mainly by type A spermatogonia. The proportion of these cells from the total number of spermatogonia reached 80 ± 3 %. With increasing age, this indicator decreased, reaching minimum values for achieving maturity (6 weeks) - 16 ± 1 %. The percentage of type B spermatogonia in the seminiferous tubule of quails on the contrary increased with age — from 5 ± 1% at 1 week old to 70 ± 2% at maturity. Thus, the age no later than 2 weeks is the most optimal for the isolation type A spermatogonia of quails. Supported by RFBR (18-29-07079).

Applying the nanobiotechnological methods for optimize the in vitro cultivation technology for cows oocytes

Aim. Investigated effect nanomaterial of highly dispersed ultra fine silica (UFS) by carbohydrate – sucrose (UFS/sucrose) on the effectiveness of meiotic maturation cows oocytes in vitro. Methods. The fresh and frozen – thawed cow oocyte-cumulus complex (OCC) was divided into four groups: three experimental in which the cultivation was carried out in a medium containing of 0, 1; 0, 01 and 0,001 % UFS/sucrose and control without adding nanomaterial. Results. It was concluded that the addition of UFS/sucrose in 0.001 % concentration is effective for elevation level of oocytes maturation and provides reception of 76,8% oocytes that induced the metaphase II of meiosis. Adding carbohydrate – sucrose (UFS/sucrose) in 0.001 % concentration to the culture medium frozen – thawed cow generative cells, make positive effect on in vitro fertilization and provide embryos quantity enhancement to 33.3 %. Conclusions. Addition of UFS/sucrose in 0.001 % concentration to the culture medium have increase effect and promote level in vitro maturation of cows oocytes rising to 76.8 %. Usage of UFS/sucrose in 0.001 % concentration as part of in vitro culture medium for cows oocyte-cumulus complex conduce rising quantity of cattle embryos to 33.3 % after in vitro fecundation frozen – thawed and maturation oocytes. Keywords: oocytes, in vitro culture, embryos, nanomaterial, ultra fine silica (UFS).

THE STUDY OF THE LEVELS OF METALLOPROTEINASES, CYTOKINES AND LYMPHOCYTE ACTIVATION MARKERS IN SEMINAL PLASMA OF MEN, DEPENDING ON FERTILITY

The study of the concentration of metalloproteinases, pro- and anti-inflammatory cytokines, lymphocyte activation markers in seminal plasma of men with oligosymptomatic forms of chronic inflammation of the urogenital tract (CIUT), depending on the fertility rate are presented in the article. Quantitative characteristics in male sperm with different forms of pathospermia were studied for matrix metalloproteinases (MMP) -2 and MMP-9 and their inhibitors - tissue inhibitors of metalloproteinases (TIMP)-1 and TIMP-2. It was shown, that during chronic inflammation of the urogenital tract of men are shifting levels of cytokine profile, reducing the concentration of metalloproteinase-2, chemokines - fractalkine and regulated by activation, expression and secretion of normal T-cells (RANTES), sharp increase in IL-8, MCP-1 and elevation of the CD25+ / CD95+, indicating that the disturbance of apoptosis of pathological forms generative cells and their accumulation in the sperm. The ratio of immunological indices IL-2/IL-4, IL-10/IL-12 was calculated and a significant increase in the IL-10/IL-12 index was noted in the group of individuals with elevated levels of hypercapitated form of sperm, and a reduced proportion of this ratio was observed in the microsomatic morphology of sperm. Prolonged inflammation in the genital area accompanied by depletion of the local immune system, resulting in the development of infertility. Immunocorrection therapy for men with CIUT should take into account the peculiarities of changes in local immunity and be differentiated depending on the prevalence of certain pathological forms of sperm and changes in the cytokine profile of the seminal plasma.

143 The Dynamics of Spermatogenesis in Guinea Fowls

Male gonads are valuable genetic material for creation of biomaterial cryobanks to preserve the genes of various animals, including poultry. Spermatogonia, which are stem cells of the testes, are of greatest interest. For effective selection of spermatogenic cells, including spermatogonia, it is necessary to know the specific features of spermatogenesis of the species of interest. In this regard, the aim of this study was to investigate the dynamics of spermatogenesis in guinea fowl. Histological examinations of guinea fowl testes (n = 90 birds) were done for 9 age categories, from 2 wk to 6 months. For each individual, at least 30 seminiferous tubules were examined. Seminiferous tubule diameters and numbers and types of spermatogenic cells (based on morphology) were determined. Overall, the histologic structure of guinea fowl testes was similar to that of mammals. Cell populations of the seminiferous tubules included Sertoli cells and generative cells, including spermatogonia, spermatocytes, spermatids, and sperm, at various stages of differentiation. Diameter of seminiferous tubules was (mean ± SEM) 36 ± 1, 58 ± 1, 64 ± 1, 65 ± 1, 110 ± 3, 178 ± 4, 233 ± 4, 274 ± 6, and 295 ± 5 µm at 2 wk, 1, 1.5, 2, 2.5, 3, 4, 5, and 6 months, respectively. Furthermore, at those ages, the number of spermatogenic cells per tubule was 18 ± 1, 20 ± 1, 29 ± 2, 30 ± 2, 68 ± 5, 114 ± 8, 186 ± 10, 400 ± 20, and 447 ± 24. Maximum percentage of spermatogonia was 72 ± 2% at 6 wk. Primary and secondary spermatocytes were first observed at 10 and 12 wk of age, respectively, whereas spermatids were first apparent at 4 months. Sperm were first identified at 5 months, with more present at 6 months. We concluded that the optimal age for retrieving testicular germ cells in guinea fowl was no later than 8 wk, as that represented the age when seminiferous tubules were dominated by spermatogonia. The study was supported by the Russian Science Foundation (Project no.16-16-04104).

Genotoxic effects of N-nitrosodimethylamine in somatic and generative cells of mice

N-Nitrosodimethylamine (NDMA) was shown to have genotoxic properties in acute and subacute studies on laboratory mice. The organ-specificity of the genotoxic effect of NDMA was revealed using the Comet assay. The most sensitive organs to the action of NDMA were kidneys and liver. DNA damage in liver cells of NDMA-treated animals at doses of 4.0 and 8.0 mg/kg, increased compared to control in 6.9 and 12.5 (р < 0.001), and in kidney cells – in 8.1 and 14.2 times (р < 0.001), respectively. NDMA also showed genotoxic activity in the reproductive cells of experimental animals, causing structural disorders of synaptonemal complexes in spermatocyte. In NDMA-treated animals at a dose of 2.0 mg/kg in acute and subacute studies, the level of spermatocytes with damaged synaptonemal complexes increased statistically significantly compared to control in 6.0 and 7.0 (р < 0.05) times, respectively.

Relationship between nuclear DNA-content of sperm cells and the timing of events in the cell cycle of Brassica campestris L. (Brassicaceae)

In this work we conducted a quantitative analysis of the nuclear DNA-content of developing sperm cells of the plant <em>Brassica campestris</em> L. The sperm cells were in young pollen grain, mature pollen grain and pollen tubes. When generative cells, at the pre-anthesis stage, split into two sperm cells, we have established that the newly-formed sperm cells begin to synthesize nuclear DNA in developing pollen grain of <em>B. campestris</em>. We measured this DNA-content during the development of sperm cells. The results indicate that during development, sperm cells of <em>B. campestris</em> have passed the G₁ phase of the cell cycle and entered the S phase, presumably then fusing with egg cells at a level of 2C, as is characteristic of G₂ type fertilization in angiosperms.