Effect of enzymatic pro-oxidant and antioxidant systems on bovine oocyte in vitro maturation

The role of reactive oxygen species (ROS) during oocyte in vitro maturation (IVM) is still controversial. Although an increase in ROS production may cause deleterious effects in cells, these reactive species may also act as signaling molecules influencing different cell functions. The aim of this study was to examine the effect of varying endogenous ROS levels during IVM on the process of bovine oocyte maturation. To do so, different enzymatic antioxidant (catalase, or superoxide dismutase + catalase, or diphenyl iodonium) or pro-oxidant systems (xanthine + xanthine oxidase, or xanthine + xanthine oxidase + catalase) were added to the culture medium. ROS levels were determined by 2′,7′-dichlorodihydrofluorescein diacetate stain, nuclear maturation was evaluated by the presence of the metaphase II chromosome configuration at 22h of IVM and cleavage rate was recorded 48hs post- in vitro fertilization. ROS levels were only significantly increased (P<0.05) by the O2 .- generating system (xanthine + xanthine oxidase + catalase), but meiotic maturation rates were significantly lower (P<0.05) in all the evaluated systems compared with the control, except for the diphenyl iodonium group. However, this last group presented a significantly lower (P<0.05) cleavage rate in comparison to the control group. These results indicate that ROS would play an essential role during oocyte maturation, since its increase or decrease beyond a physiological level significantly reduced nuclear or cytoplasmic maturation rates in bovine oocytes.

MORPHOLOGICAL AND CHROMOSOMAL CHARACTERIZATION OF ORCHID Peristylus goodyeroides Lindl. FROM CURUG SETAWING, KULONPROGO

Peristylus goodyeroides is a terestrial orchid that scattered around Southeast Asia. Morphological characters of P. goodyeroides can vary, depending on the ecological factors and habitat. Cytological characters in the form of chromosome configurations can be used as a taxonomic tool for the process of identifying and understanding variations in taxa. The purpose of this study was to determine the morphological characters and chromosome configuration of the P. goodyeroides from Curug Setawing, Kulonprogo. The method used was morphological characterization and plant chromosome preparation by squash method with the main steps of fixation, maceration, staining and observation. Data were analyzed with the help of Image raster 3, Corel Draw X7, and Microsoft Excel 2013. P. goodyeroides from Curug Setawing has the morphological characters of root tubers, cylindrical stems, ovate leaf shape, convolutive leaf arrangement and creamy white flowers. The orchid has a number of chromosomes 2n = 10 with a karyotype formula of 2n = 2x = 8m + 2t. Metacentric chromosomes are found on chromosomes 1-8 and telocentric chromosomes 9-10. The absolute arm length of the chromosomes has a range of 2.03-3.44 μm, the relative arm length of the chromosomes is 2.21-3.32 μm, the length of the p arm is 1.13-1.58 μm and the q arm is 1.23-2.12 μm.

Metazoan-like kinetochore arrangement masked by the interphase RabI configuration

During cell cycle progression in metazoan, the kinetochore, the protein complex attached to centromeres which directly interacts with the spindle microtubules, the vehicle of chromosome segregation, is assembled at mitotic onset and disassembled during mitotic exit. This program is assumed to be absent in budding and fission yeast because kinetochore proteins are stably maintained at the centromeres throughout the entire cell cycle. In this work, we show that the assembly program at the mitotic onset of the Ndc80 complex, a crucial part of the outer kinetochore, is unexpectedly conserved in Schizosaccharomyces pombe. We have identified this behavior by removing the Rabl chromosome configuration during interphase, in which centromeres are permanently associated with the nuclear envelope beneath the spindle pole body. Hence, the Rabl configuration masks the presence of a program to recruit Ndc80 at mitotic onset in fission yeast, similar to that taking place in metazoan. Besides the evolutionary implications of our observations, we think that our work will help understand the molecular processes behind the kinetochore assembly program during mitotic entry using fission yeast as the model organism.

A 1Ns Disomic Addition from Psathyrostachys Huashanica Keng Confers Resistance to Powdery Mildew in Wheat

Powdery mildew is a fungal disease that threatens wheat production throughout the world. Breeding resistant cultivars is an effective way to reduce harm caused by powdery mildew. In this study, 35 wheat-Psathyrostachys huashanica-derived lines were developed by crossing common wheat and P. huashanica Keng (2n = 2x = 14, NsNs) using embryo culture. Resistance to powdery mildew in the derived lines was identified at the seedling and adult stages. Line H5-5-4-2 was selected with immunity to powdery mildew at both growth stages. The chromosome structure of this line was characterized by cytology, genomic in situ hybridization (GISH), and expressed sequence tag-sequence-tagged site (EST-STS) analysis. The chromosome configuration was 2n = 44 = 22II. Two P. huashanica chromosomes with strong hybridization signals were detected by GISH analysis. Among 83 EST-STS markers that covered all seven homologous groups in wheat, three pairs of STS markers, BE497584, BF202643, and BG262410, located in wheat homologous group 1 amplified clear specific bands related to P. huashanica. The results indicated that resistant line H5-5-4-2 was a wheat-P. huashanica 1Ns disomic addition line.

Spindle and chromosome configuration analysis of human biopsied versus non-biopsied embryos by confocal laser scanning microscopy following vitrification

SummaryThe aim of this study was to investigate the effects of zona drilling and biopsy on day 3 followed by vitrification on day 5 on the cytoskeleton and development of human embryos, by analysing survival rates and spindle and chromosome configurations by fluorescence and confocal laser scanning microscopy in human biopsied and non-biopsied embryos. In total, 98 human blastocysts (50 non-biopsied and 48 following biopsy on day 3) were vitrified on day 5 using either a commercial dimethyl sulphoxide (DMSO)-free vitrification kit or increasing concentrations of DMSO/EG (5%/5–10%/10–20%/20%). Following warming, the blastocysts were allowed to recover in culture for 24 h and were immunostained with α-tubulin, acetylated tubulin, and/or γ-tubulin antibodies in combination with 4′,6-diamidino-2-phenylindole (DAPI). Labelled embryos were examined by both fluorescence and confocal laser scanning microscopy. The survival rates following warming (92% non-biopsied vs 83.3% biopsied) and the incidence of normal spindle chromosome configurations was not statistically different between the two groups (65.2% non-biopsied vs 59.2% biopsied, P>0.05). The incidence of spindle abnormalities including multipolarity, chromosome lagging, congression failure and chromosome bridging were also similar between the two groups (P>0.05). This study is the first to compare the incidence of cytoskeletal abnormalities in biopsied and non-biopsied human embryos following vitrification. We conclude that there was no significant difference in the survival rates and the incidence of spindle abnormalities between the two groups.

Timing mechanism of sexually dimorphic nervous system differentiation

The molecular mechanisms that control the timing of sexual differentiation in the brain are poorly understood. We found that the timing of sexually dimorphic differentiation of postmitotic, sex-shared neurons in the nervous system of the Caenorhabditis elegans male is controlled by the temporally regulated miRNA let-7 and its target lin-41, a translational regulator. lin-41 acts through lin-29a, an isoform of a conserved Zn finger transcription factor, expressed in a subset of sex-shared neurons only in the male. Ectopic lin-29a is sufficient to impose male-specific features at earlier stages of development and in the opposite sex. The temporal, sexual and spatial specificity of lin-29a expression is controlled intersectionally through the lin-28/let-7/lin-41 heterochronic pathway, sex chromosome configuration and neuron-type-specific terminal selector transcription factors. Two Doublesex-like transcription factors represent additional sex- and neuron-type specific targets of LIN-41 and are regulated in a similar intersectional manner.

Characterization of wheat – Psathyrostachys huashanica small segment translocation line with enhanced kernels per spike and stripe rust resistance

Psathyrostachys huashanica Keng (2n = 2x = 14, NsNs), a distant wild relative of common wheat, possesses rich potentially valuable traits, such as disease resistance and more spikelets and kernels per spike, that could be useful for wheat genetic improvement. Development of wheat – P. huashanica translocation lines will facilitate its practical utilization in wheat breeding. In the present study, a wheat – P. huashanica small segmental translocation line, K-13-835-3, was isolated and characterized from the BC1F5 population of a cross between wheat – P. huashanica amphiploid PHW-SA and wheat cultivar CN16. Cytological studies showed that the mean chromosome configuration of K-13-835-3 at meiosis was 2n = 42 = 0.10 I + 19.43 II (ring) + 1.52 II (rod). GISH analyses indicated that chromosome composition of K-13-835-3 included 40 wheat chromosomes and a pair of wheat – P. huashanica translocation chromosomes. FISH results demonstrated that the small segment from an unidentified P. huashanica chromosome was translocated into wheat chromosome arm 5DS, proximal to the centromere region of 5DS. Compared with the cultivar wheat parent CN16, K-13-835-3 was highly resistant to stripe rust pathogens prevalent in China. Furthermore, spikelets and kernels per spike in K-13-835-3 were significantly higher than those of CN16 in two growing seasons. These results suggest that the desirable genes from P. huashanica were successfully transferred into CN16 background. This translocation line could be used as novel germplasm for high-yield and, eventually, resistant cultivar breeding.

46 SPINDLE CONFIGURATION OF IN VITRO-MATURED BOVINE OOCYTES EXPOSED TO SODIUM CHLORIDE OR SUCROSE PRIOR TO CRYOTOP VITRIFICATION

It has been previously described that a simple treatment with medium containing elevated NaCl or sucrose concentrations increases the cryotolerance and developmental competence of in vitro-matured porcine oocytes after vitrification and parthenogenetic activation (Lin et al. 2009 Reprod. Fertil. Dev. 21, 338–344). This work was designed to study whether the exposure to increased concentrations of NaCl or sucrose before vitrification improves cryotolerance of in vitro-matured bovine oocytes. In Experiment 1, in vitro-matured oocytes were exposed to different NaCl and sucrose concentrations (from 375 to 808 mOsm) for 1 h. In Experiment 2, and according to the results obtained in the first experiment, oocytes were exposed to 375 mOsm NaCl or sucrose solution, vitrified, and warmed. Nontreated oocytes were used as controls. In both experiments, oocytes were fixed after treatment and microtubule, and chromosome distribution was analysed by immunocitochemistry. All statistical analyses were conducted with the IBM SPSS 19 for Windows (IBM corp., Chicago, IL). ANOVA was performed to analyse differences in meiotic spindle. Statistical significance was set at P < 0.05. After exposure to 375 mOsm of NaCl or sucrose, similar percentages of oocytes showing normal chromosome distribution were obtained compared to the control group (83.4, 71.8, and 85.0%, respectively). Groups treated with higher concentrations (443 to 808 mOsm) triggered significantly lower proportions of normal spindles. After vitrification/warming, no significant differences were observed between nonvitrified oocytes (71.3%) and those treated with NaCl before vitrification/warming procedure (41.9%) when normal chromosome organisation was analysed. Significantly higher percentages of normal chromosome configuration were observed when oocytes were exposed to sucrose before vitrification (34.2%) compared with control-vitrified oocytes (23.3%). However, pretreatment with NaCl or sucrose before vitrification did not trigger significant differences in terms of percentages of normal microtubule configuration (41.9 and 32.9%, respectively) compared with control-vitrified oocytes (40.2 and 24.4%, respectively), although both treatments differed significantly from control (79.1 and 81.7%, respectively). In conclusion, this study showed that a 375-mOsm NaCl or sucrose pretreatment of bovine oocytes before vitrification did not have a deleterious effect on the organisation of the meiotic spindle of vitrified/warmed bovine oocytes. Further experiments are required to investigate whether in vitro-matured oocytes subjected to this osmotic treatment could improve their development competence after being vitrified/warmed.

45 SPINDLE CONFIGURATION AND DNA FRAGMENTATION OF VITRIFIED BOVINE OOCYTES AFTER IN VITRO MATURATION WITH L-CARNITINE AND/OR RESVERATROL

After cryopreservation, oocytes may suffer morphological and functional damage, due to the high cytoplasm lipid content and to the reactive oxygen species formation. The aim of this work was to evaluate the spindle configuration and the DNA fragmentation of vitrified/warmed oocytes after in vitro maturation (IVM) in a media supplemented with l-carnitine and/or resveratrol, a lipolytic and antioxidant agent, respectively. The IVM viable COC with at least 3 cumulus cell layers and homogenous cytoplasm were randomly distributed into 4 groups: (1) control: conventional IVM media with TCM-199, epidermal growth factor, and 10% FCS; (2) L-CAR: control media supplemented with 0.6 mg mL–1 of l-carnitine; (3) RES: control media supplemented with 1 μM mL–1 of resveratrol; and 4) L+R: control media supplemented with 0.6 mg mL–1 of l-carnitine and 1 μM mL–1 of resveratrol. After 22 h of IVM, half of the COC from each group were vitrified and warmed, using the cryotop methodology. After warming, the oocytes were allowed to recover in their respective media for 2 additional hours. After 24 h of IVM, oocytes from all treatments were completely denuded and fixed and stained using specific fluorescent probes. The microtubule/chromosome configuration and the DNA fragmentation were analysed by immunocytochemistry under a fluorescent microscope (A.40FL, Carl Zeiss, Oberkochen, Germany). All statistical analyses were conducted with IBM SPSS 19 (IBM; Chicago, IL, USA). ANOVA was performed to analyse differences in meiotic spindle configuration, and the Chi-squared test was used for DNA fragmentation. The significance level was 5%. Although vitrification may cause severe oocyte damage, IVM with l-carnitine alone or in association with resveratrol was able to reduce the percentage of abnormal spindle configurations (Table 1), whereas the addition of resveratrol alone or its association with l-carnitine reduced DNA fragmentation of IVM oocytes after a vitrification/warming process. These results indicate the IVM supplementation with RES and/or L-CAR could modify oocyte composition, increasing its cryotolerance. However further studies are required to confirm the beneficial effect of these molecular interactions. Table 1.Evaluation of spindle configuration (Experiment 1) and apoptotic cell status (Experiment 2) of fresh or vitrified/warmed oocytes matured with RES and/or L-CAR