Effects of Melatonin on Spermatozoa Activity and Associated Mechanisms in Heat-Stressed Rats

In animals,heat stress(HS)disrupts spermatogenesis,reducing sperm quality and,in severe cases,potentially inducing the loss of male reproductive function.Melatonin confers significant resistance to oxidative stress and apoptosis;however,its specific effects on rat spermatocytes and the mechanism underlying its anti-HS effects remain inadequately explored.Therefore,this study aimed to analyze the effects of melatonin at different concentrations on sperm cell activity in heat-stressed rats.Modeling heat stress injury,sperm viability and density assay,sperm plasma membrane integrity analysis,and oxidative stress assay of testicular tissue were conducted.The results revealed that HS caused sperm cell injury.However,the intraperitoneal injection of melatonin effectively improved spermatozoa quality,and a dose of 1 mM significantly alleviated the HS-induced damage.Moreover,HS increased the levels of oxidative and endoplasmic reticulum(ES)stress in rat testicular tissues,inducing germ cell apoptosis and pathological changes.Similarly,melatonin treatment improved sperm cell viability and density,inhibited germ cell apoptosis,and reduced oxidative and ES stress levels.Overall,melatonin effectively reduced the adverse effects of HS on rat sperm cells,and an intraperitoneal injection of 1 mM(0.6966 mg)melatonin facilitated the normal production of spermatozoa.Notably,its mechanism may involve reduced ES and oxidative stress levels in testicular tissues,increased expression of the anti-apoptotic protein Bcl-2,and inhibition of germ cell apoptosis.

Effects of Nitrogen Application Level on Rice Nutrient Uptake and Ammonia Volatilization

The effects of different nitrogen application levels on nutrient uptake and ammonia volatilization were studied with the rice cultivar Zheyou 12 as a material.The accumulative amounts of nitrogen,phosphorus and potassium in rice plants across all growth stages showed a trend to increase with increasing nitrogen application levels from 0 to 270 kg/hm 2,but decreased at nitrogen application levels exceeding 270 kg/hm 2.Moreover,the accumulative uptake of nitrogen,phosphorus and potassium by the rice plants was increased by application of organic manure in combination with 150 kg/hm 2 nitrogen.The nitrogen uptake was high during the jointing to heading stages.Correlation analysis showed that rice yield was positively correlated with the accumulative uptake of nitrogen,phosphorus and potassium by the rice plants.The highest correlation coefficient observed was between the amount of nitrogen uptake and rice yield.The rate and accumulative amounts of ammonia volatilization increased with increasing nitrogen fertilizer application level.Compared with other stages,the rate and accumulative amount of ammonia volatilization were higher after base fertilizer application.The ammonia volatilization rates in response to the nitrogen application levels of 270 kg/hm 2 and 330 kg/hm 2 were much higher than those in the other treatments.The loss of nitrogen through ammonia volatilization accounted for 23.9% of the total applied nitrogen at the nitrogen application level of 330 kg/hm 2.

Proteomic Analysis of Fruit Bending in Cucumber (Cucumis sativus L.)

In cucumber, fruit shape is an important quality criterion, and fruit bending is known to limit growth, yield, and taste. To investigate the post-transcriptional changes that regulate fruit bending and to better understand the underlying molecular mechanisms, we generated a proteomic profile of the abdomen and back of cucumber bending fruit. Two-dimensional gel electrophoresis （2-DE） allowed the detection of approximately 900 distinct protein spots in each gel, 32 of which were differentially expressed in the abdomen and back of bending cucumber fruit. Ten of the differentially expressed proteins were analyzed using matrix-assisted laser ionization time of flight mass spectrometry （MALDI-TOF/MS）. A search of primary databases showed that the identified proteins are involved in various metabolic processes and cellular responses, including photosynthesis metabolism, energy metabolism, defense and stress response, and regulation. The identified proteins included large subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase, which are involved in photosynthesis and photorespiratory metabolism, and isocitrate dehydrogenase, which is involved in the tricarboxylic acid cycle. It is possible that imbalances in catabolic and anabolic processes directly affect the bending of cucumber fruit. The predicted function of the cobalamin- independent methionine synthase isozyme is closely related to ethylene biosynthesis; fruit bending may be regulated by ethylene, or by ethylene signaling crosstalk during fruit development. The 14-3-3 protein is usually considered to be a regulation-related protein, which plays a role in regulating cell hyperplasia, cell differentiation during growth, and apoptosis during senescence. Involvement of guanosine triphosphate （GTP）-binding proteins in signal transmission is known to regulate the development of cells in cucumber fruits and to play a role in fruit shape variation. Patterns of protein expression showed high repeatability. We hypothesize that these proteins may play an important role in growth and bending of cucumber fruits. The results of our study provide insight into the genetic mechanism underlying fruit bending in cucumber, and may help to promote cultivation of new varieties with superior fruits.

A Novel Angiotensin I Converting Enzyme Inhibitory Peptide from the Milk Casein:Virtual Screening and Docking Studies

Angiotensin I converting enzyme （ACE） plays an important physiological role in the regulation of hypertension. In this study, we applied virtual screening to discover a novel angiotensin I converting enzyme inhibitory peptides from milk casein. One potential hit was identified based on docking scores, subsequently confirmed by activity studies in vitro （IC50=20.85 μmol L-1）. The proposed peptide in this study contains a unique sequence, Lys-Val-Leu-Ile-Leu-Ala. Moreover, we performed the docking studies to understand the binding mode between the enzyme and peptide hit.

Production of hispidin polyphenols from medicinal mushroom Sanghuangporus vaninii in submerged cultures

Objective: The medicinal mushroom Sanghuangporus vaninii produces pharmaceutically valuable hispidin polyphenols in natural habitats. However, due to the slow growth in nature, S. vaninii grown in the field(sclerotia) is not reliable for pharmaceutical purposes. Although higher biomass of fungal mycelia can be obtained in submerged cultures, the accumulation of hispidin polyphenols is rare.Methods: In this study, the polyunsaturated fatty acids(PUFAs), linoleic acid(LA), linolenic acid(ALA),and methyl jasmonate(Me Ja) were employed as the stimulant agents to coordinate the accumulation of biomass and hispidin polyphenols in its submerged cultures.Results: The addition of LA and ALA promoted the mycelial accumulation, while the addition of Me Ja inhibited the growth of S. vaninii concomitant with reduced total polyphenols. UPLC-Triple-TOF-MS analysis revealed an increased production of hispidin, phellinstatin, pinnilidine, and its derivatives upon the addition of LA and ALA, and hypholomine B and its isomer, 3,14’-bihispidinyl, and phelligridin E upon the addition of Me Ja on day 13. Intriguingly, total polyphenols from the Me Ja-supplementing cultures harbored a high capacity in scavenging free radicals. Chemical structural analysis showed that hispidin polyphenols had higher antioxidant activity due to more hispidin moieties induced by Me Ja.Conclusion: The supplement of PUFAs affects the synthesis and composition of hispidin polyphenols in S.vaninii. Our results provide a possibility to coordinate the production of hispidin polyphenols via submerged cultures of S. vaninii.

Rescued virus from infectious cDNA clone of rabbit hemorrhagic disease virus is adapted to RK13 cells line

Based on the infectious full-length cDNA clone of rabbit hemorrhagic disease virus (RHDV), the in vitro transcripts are introduced into RK13 cells. 12 h later, CPE could be observed clearly, and virual antigen could also be detected by IFA. The titre of the recovered virus is 104.6/mL. Immune electron micro-scopic observation of the virus particles revealed that the particles were rotund with a diameter of about 30 nm. Besides, virus titre quantification obtained by qRT-PCR showed a correlation between time from infection and virus titre. All these results showed that we have recovered RHDV from RK13 cells by re-verse genetics technology successfully, and this would be very useful in studies of the antigenicity, virulence, pathogenesis, maturation and new type vaccines of RHDV.

Kernel position effects of grain morphological characteristics by X-ray micro-computed tomography (μCT)

Grain size and shape are important factors for yield and quality.The difference in grain phenotypic characteristics in the same maize hybrid is related to its position in the ear.This study aimed to clarify the distribution characteristics of grain morphological characteristics in the ear and to provide guidance for research of grain phenotype and kernel position effects.Three maize hybrids were used in the experiment,namely,Denghai 618(DH618),KX3564,and Xianyu 335(XY335),and the kernel number per row were 40,40,and 36,respectively.The X-rayμCT was applied to obtain five kernel morphological indicators,including grain length,width,thickness,volume,surface area.Grain sphericity,length-width ratio,specific surface area,and volume coefficient were further calculated.The results showed that there were three types of maize ear morphological indicators trends:grain length,width,volume,and surface area were parabolic;thickness and sphericity were inverted parabolic;length-to-width ratio and specific surface area were irregular.The volume coefficient of grain at different parts of the ear,namely the relation coefficient between grain volume and grain length,width,and thickness,was determined.The average value of the middle grains morphological indicators of the ear was taken to select kernels representing stable characteristics of the variety.Within the range of 5%deviation from the morphological mean value of the middle grains of the ear,the grains in the middle part accounted for 26.39%of the total ear,about 10 grains extending from the 14th grain at the base of the ear to the top.Within the range of 10%deviation,the middle accounted for 47.22%,about 18 grains extending from the 12th grain at the base of the ear to the top.This study found that grain morphological indicators were greatly different at different positions of the maize ear,and showed different change rules as extend from the base to the top of the ear.Therefore,there were different grain volume coefficients at different positions of maize ear.And the representative sampling range on maize ear was determined based on the comprehensive analysis of different morphological indexes variation of grain.