Signalling Events and Associated Pathways Related to the Mammalian Sperm Capacitation

Capacitation is a biological phenomenon occurring prior to fertilization and is a multiple event process. Many physiological and biochemical changes takes place during the process; these changes are related to lipid composition of membrane, intracellular modulation of ion concentration, protein phosphorylation, sperm movement and membrane permeability. These events occur when the sperm is exposed to the new environment of ion concentration in the female reproductive tract. Ions such as bicarbonate and calcium facilitate capacitation by activating adenylyl cyclase, thus initiating protein kinase A (PKA) signalling cascade. Extracellular‐regulated kinase pathway is activated by ligand binding to the membrane receptors and intracellular activation by reactive oxygen species (ROS). Activation of these pathways leads to the phosphorylation of different proteins, which is associated with events such as capacitation, hyperactivation and acrosome reaction that are essential for successful fertilization. Extensive studies were carried out on protein phosphorylation in relation to capacitation, but its role still remains ambiguous.     

不同来源大豆品种籽粒品质的比较研究

以辽宁20年代、辽宁当代以及与辽宁近纬度的美国俄亥俄州当代育成的亚有限结荚习性大豆品种各4个为试材,研究了不同来源大豆品种籽粒品质的差异,以及不同磷酸二铵施肥水平对大豆籽粒品质的影响.结果表明:就试验采用的品种而言,俄亥俄州立大学更注重籽粒脂肪含量的改良,而且遗传获得较大,而辽宁省育成的新品种其脂肪含量也比老品种稍高一些,蛋白质含量则有所下降.就品种来说,老品种Mukden的品质最好,蛋脂总含量高达64.7%,辽宁新品种中辽豆12号最好,俄亥俄新品种中OhioFG1最好.蛋白质含量以Mukden含量最高,达44.85%,脂肪含量以Darby含量最高,为21.39%.与不施肥相比,150 kg/hm2、300 kg/hm2磷酸二铵施肥处理会使各品种的蛋白质含量得到提高,脂肪含量有所降低,从不同来源品种组平均值来看,施用磷酸二铵300 kg/hm2的处理,大豆籽粒的蛋白质含量高于150 kg/hm2处理,脂肪含量则与之相反.     

Enzyme activity and carbon dioxide evolution from upland and wetland rice soils under three agricultural practices in hilly regions

Summary Dehydrogenase activity (a measure of microbial biomass), urease activity and CO₂ evolution were measured in soils planted to rice (Oryza sativa L.) under three different agricultural practices prevalent in hill regions. The effects of hill slope, terrace and valley agriculture were investigated for two cropping seasons. The valleys and terraces were kept flooded during each cropping season while the hill slopes were cultivated with dryland practices. The type of agricultural practice and the date of observation had a significant influence on enzyme activity and CO₂ evolution. A positive correlation was observed between dehydrogenase and urease activity and soil moisture content. Dehydrogenase and urease activity and soil respiration were positively correlated among themselves. The activity of both enzymes and CO₂ evolution were highest in valley soils followed by terrace and hill-slope sites.     

Performance stability of maize genotypes across diverse hill environments in Nepal

The national maize improvement program in Nepal regularly receives elite maize (Zea mays L.) genotypes from CIMMYT and other countries and tests them for their performance stability in highly diverse environments. Studies were conducted on research stations and farmers’ fields at five sites in three years to determine performance stability of exotic maize genotypes. Replicated on-station and on-farm studies were conducted using 25 and 10 genotypes, respectively, including a local check and an improved check (Manakamana-3), in 2004–2006. We analyzed grain yield, days to flowering, plant and ear height, plant population, husk cover, and plant and ear aspect. Stability and genotype superiority for grain yield was determined using genotype and genotype × environment (GGE) biplot analysis that compares among a set of genotypes with a reference ‘ideal’ genotype, which has the highest average value of all genotypes and is absolutely stable. Several genotypes produced significantly higher grain yield than the local check. Four genotypes (‘Across9942 × Across9944’, ‘Open Ended White Hill Population’, ‘Population 44C10’ and ‘ZM621’), that produced significantly higher grain yield than the improved check, also had other agronomic traits (days to flowering, plant and ear height, number of ears, resistance to leaf blight, plant and ear aspect and husk cover tightness) equal to or better than the improved check. GGE-biplot analysis showed that Across9942 × Across9944 and ZM621 were the most superior genotypes in the on-station and on-farm trials, respectively. The findings from this study provide new information on the stability of the maize genotypes that are also adapted to other regions of the world. Such information could be useful for maize improvement program for the highlands in Nepal and other similar environments.     

Effect of Red Beet and Betaine Modulating Oxidation and Bioactivity of Rainbow Trout

The present study compares a control diet to four experimental diets, in which two red beet (14% and 28%) and two betaine levels (0.9% and 1.63%) were incorporated in rainbow trout diets according to a factorial design. The effects of the inclusion of different red beet and betaine concentrations on fatty acid (FA) profile, lipid peroxidation, and antioxidant activity on rainbow trout fillets were investigated. Although no significant differences were observed with the control group, results indicated that red beet and betaine improved fish fillet FA profile, producing an increase in polyunsaturated FAs, mainly docosahexaenoic acid. Higher red beet and betaine concentrations increased flavonoid and phenolic content in the diets; however, no effects were observed for the antioxidant properties of rainbow trout fillets.     

Encapsulation of Bolbophorus damnificus (Digenea: Bolbophoridae) Metacercariae in Juvenile Channel Catfish,Ictalurus punctatus,Is Linked to Delayed‐onset Mortality

Bolbophorus damnificus (Digenea: Bolbophoridae) causes significant economic losses in catfish aquaculture in the southeastern USA. To determine mortality trends associated with B. damnificus exposure, three separate disease challenges were conducted. The first challenge exposed channel catfish, Ictalurus punctatus, fingerlings (7–13 cm) to approximately 285 B. damnificus cercariae/L, while the second exposed fish to approximately 215 cercaria/L. Fish were monitored for morbidity and mortality for 28 d. In both studies, mortality first occurred 8 d postchallenge (PC) and peaked at 9 and 10 d PC, respectively. Mortality had subsided by 14 d PC, with only sporadic mortality occurring >15 d PC. Dead and moribund fish presented with lesions consistent with B. damnificus infection. A third challenge was performed to record histological changes associated with parasite development from initial exposure up to the cessation of mortality. Catfish (2–5 cm) were exposed as described above to a range covering 0, 35, 70, 100, 150, 175, and 215 cercariae/L. Each day, two fish were sampled from each treatment. Mortality trends were consistent with previous challenges. The mortality window coincided with parasite encapsulation, neovascularization, and development of the host‐derived cyst, suggesting that morbidity and mortality are linked to host pathophysiological changes in response to metacercariae encapsulation.     

Detection of benzimidazole resistance in Haemonchus contortus using RFLP-PCR technique

Benzimidazole (BZ) resistance in Haemonchus contortus is linked primarily with the mutation in the beta-tubulin isotype 1 gene that substitute phenylalanine (Phe) to tyrosine (Tyr) at 200 codon of the gene. In the present study, a new restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) technique has been developed for detection of BZ resistance in the beta-tubulin isotype 1 gene of H. contortus. The technique utilizes two primers viz. AvikaF and AvikaR to amplify the region containing mutation in the beta-tubulin gene followed by restriction digestion. After digestion, the 'rr' individuals (homozygous resistant) revealed 257 and 48 bp bands, the 'rS' individuals (heterozygous) showed 305, 257 and 48 bp bands, while 'SS' individuals (homozygous susceptible) revealed uncut 305 bp band. A total of 162 adult male H. contortus collected from Avikanagar, Jaipur and Bikaner regions (54 from each region) were genotyped for analyzing BZ resistance in the beta-tubulin gene. Out of which, 130 adults were 'rr' types, 20 'rS' types and 12 'SS' types. The results showed that genotypic frequencies of different genotypes (rr, rS and SS) were highly significant difference among the three regions (P<0.001). The 'rr' individuals were higher (98%) in Jaipur followed by Avikanagar (93%) and Bikaner (50%) regions. Overall, the prevalence of BZ resistant allele (r) was higher (86%) as compared to BZ susceptible allele (S) (14%). The technique was also found suitable for genotyping of larvae of H. contortus and yielded reproducible results. The study indicated that RFLP-PCR is an easy, reproducible and less expensive than allele specific PCR. This technique will be helpful in establishing the prevalence rate of BZ resistance in H. contortus and can also be utilized for existing worm control programme.     

Identification and characterization of SNPs in released,landrace and wild accessions of mungbean (Vigna radiata (L.) Wilczek) using whole genome re-sequencing

Journal of Crop Science and Biotechnology - Mungbean [Vigna radiata (L.) R. Wilczek var. radiata] is vital grain legume having nutritional and socio-economic importance, especially in the...