Effects of melatonin on sperm quality, enzyme activity, antioxidant gene expression and fertility of cryopreserved bovine semen.

Melatonin (MLT) has strong antioxidant capacity and can reduce the damage caused by oxidative stress in sperm, but there is still little content in the field we have studied. In this study, we are committed to scientific research on adding melatonin to Belgian blue bull semen diluent for cryopreservation. Different concentrations (0, 0.1, 0.3, 0.5 or 0.7 mg/mL) of MLT were added diluent. Sperm kinetic parameters, enzyme activity, antioxidant gene expression and fertility were analyzed after thawing. The results showed that MLT concentration of 0.3 mg/mL exerted positive effects on post-thaw kinetic parameters. Compared with other groups, 0.3 mg/mL MLT treated sperm acrosome and plasma membrane integrity, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels significantly increased. Meanwhile, the mRNA expression of antioxidant genes SOD2, CAT and GPx increased in the 0.3 mg/mL MLT treatment group, and the mRNA expression of apoptosis genes Caspase-3 and Bax were significantly reduced. In addition, in vitro fertilization (IVF) embryo cleavage, blastocyst rate and artificial insemination (AI) pregnancy rate were higher in 0.3 mg/mL MLT. Therefore, MLT showed cryoprotective capacity to the freezing diluent used for Belgian blue bull sperm during the process of freezing-thawing, and the optimal concentration of MLT for the frozen diluent was 0.3 mg/mL.

Effector enrichment by Candidatus Liberibacter promotes Diaphorina citri feeding via Jasmonic acid pathway suppression.

BACKGROUND: Citrus huanglongbing (HLB) is a devastating disease caused by Candidatus Liberibacter asiaticus (CLas) that affects the citrus industry. In nature, CLas relies primarily on Diaphorina citri Kuwayama as its vector for dissemination. After D. citri ingests CLas-infected citrus, the pathogen infiltrates the insect's body, where it thrives, reproduces, and exerts regulatory control over the growth and metabolism of D. citri. Previous studies have shown that CLas alters the composition of proteins in the saliva of D. citri, but the functions of these proteins remain largely unknown. RESULTS: In this study, we detected two proteins (DcitSGP1 and DcitSGP3) with high expression levels in CLas-infected D. citri. Quantitative PCR and Western blotting analysis showed that the two proteins were highly expressed in the salivary glands and delivered into the host plant during feeding. Silencing the two genes significantly decreased the survival rate for D. citri, reduced phloem nutrition sucking and promoted jasmonic acid (JA) defenses in citrus. By contrast, after overexpressing the two genes in citrus, the expression levels of JA pathway-associated genes decreased. CONCLUSION: Our results suggest that CLas can indirectly suppress the defenses of citrus and support feeding by D. citri via increasing the levels of effectors in the insect's saliva. This discovery facilitates further research into the interaction between insect vectors and pathogens. © 2024 Society of Chemical Industry.

Prevalence, antibiotic susceptibility and genomic analysis of Salmonella from retail meats in Shaanxi, China.

Salmonella is a major foodborne pathogen that poses a substantial risk to food safety and public health. This study aimed to assess the prevalence, antibiotic susceptibility, and genomic features of Salmonella isolates recovered from 600 retail meat samples (300 pork, 150 chicken and 150 beef) from August 2018 to October 2019 in Shaanxi, China. Overall, 40 (6.67 %) of 600 samples were positive to Salmonella, with the highest prevalence in chicken (21.33 %, 32/150), followed in pork (2.67 %, 8/300), while no Salmonella was detected in beef. A total of 10 serotypes and 11 sequence types (STs) were detected in 40 Salmonella isolates, with the most common being ST198 S. Kentucky (n = 15), ST13 S. Agona (n = 6), and ST17 S. Indiana (n = 5). Resistance was most commonly found to tetracycline (82.50 %), followed by to ampicillin (77.50 %), nalidixic acid (70.00 %), kanamycin (57.50 %), ceftriaxone (55.00 %), cefotaxime (52.50 %), cefoperazone (52.50 %), chloramphenicol (50.00 %), levofloxacin (57.50 %), cefotaxime (52.50 %), kanamycin (52.50 %), chloramphenicol (50.00 %), ciprofloxacin (50.00 %), and levofloxacin (50.00 %). All ST198 S. Kentucky isolates showed multi-drug resistance (MDR; ≥3 antimicrobial categories) pattern. Genomic analysis showed 56 distinct antibiotic resistance genes (ARGs) and 6 target gene mutations of quinolone resistance determining regions (QRDRs) in 40 Salmonella isolates, among which, the most prevalent ARG types were related to aminoglycosides and ß-lactams resistance, and the most frequent mutation in QRDRs was GyrA (S83F) (47.5 %). The number of ARGs in Salmonella isolates showed a significant positive correlation with the numbers of insert sequences (ISs) and plasmid replicons. Taken together, our findings indicated retail chickens were seriously contaminated, while pork and beef are rarely contaminated by Salmonella. Antibiotic resistance determinants and genetic relationships of the isolates provide crucial data for food safety and public health safeguarding.

A novel detection method for neuronal death indicates abnormalities in intracellular membranous components in neuronal cells that underwent delayed death.

Acute neuronal degeneration is always preceded under the light and electron microscopes by a stage called microvacuolation, which is characterized by a finely vacuolar alteration in the cytoplasm of the neurons destined to death. In this study, we reported a method for detecting neuronal death using two membrane-bound dyes, rhodamine R6 and DiOC6(3), which may be associated with the so-called microvacuolation. This new method produced a spatiotemporally similar staining pattern to Fluoro-Jade B in kainic acid-damaged brains in mice. Further experiments showed that increased staining of rhodamine R6 and DiOC6(3) was observed only in degenerated neurons, but not in glia, erythrocytes, or meninges. Different from Fluoro-Jade-related dyes, rhodamine R6 and DiOC6(3) staining is highly sensitive to solvent extraction and detergent exposure. Staining with Nile red for phospholipids and filipin III for non-esterified cholesterol supports that the increased staining of rhodamine R6 and DiOC6(3) might be associated with increased levels of phospholipids and free cholesterol in the perinuclear cytoplasm of damaged neurons. In addition to kainic acid-injected neuronal death, rhodamine R6 and DiOC6(3) were similarly useful for detecting neuronal death in ischemic models either in vivo or in vitro. As far as we know, the staining with rhodamine R6 or DiOC6(3) is one of a few histochemical methods for detecting neuronal death whose target molecules have been well defined and therefore may be useful for explaining experimental results as well as exploring the mechanisms of neuronal death.

Different changes in pre- and postsynaptic components in the hippocampal CA1 subfield after transient global cerebral ischemia.

To date, ischemia-induced damage to dendritic spines has attracted considerable attention, while the possible effects of ischemia on presynaptic components has received relatively less attention. To further examine ischemia-induced changes in pre- and postsynaptic specializations in the hippocampal CA1 subfield, we modeled global cerebral ischemia with two-stage 4-vessel-occlusion in rats, and found that three postsynaptic markers, microtubule-associated protein 2 (MAP2), postsynaptic density protein 95 (PSD95), and filamentous F-actin (F-actin), were all substantially decreased in the CA1 subfield after ischemia/reperfusion (I/R). Although no significant change was detected in synapsin I, a presynaptic marker, in the CA1 subfield at the protein level, confocal microscopy revealed that the number and size of synapsin I puncta were significantly changed in the CA1 stratum radiatum after I/R. The size of synapsin I puncta became slightly, but significantly reduced on Day 1.5 after I/R. From Days 2 to 7 after I/R, the number of synapsin I puncta became moderately decreased, while the size of synapsin I puncta was significantly increased. Interestingly, some enlarged puncta of synapsin I were observed in close proximity to the dendritic shafts of CA1 pyramidal cells. Due to the more substantial decrease in the number of F-actin puncta, the ratio of synapsin I/F-actin puncta was significantly increased after I/R. The decrease in synapsin I puncta size in the early stage of I/R may be the result of excessive neurotransmitter release due to I/R-induced hyperexcitability in CA3 pyramidal cells, while the increase in synapsin I puncta in the later stage of I/R may reflect a disability of synaptic vesicle release due to the loss of postsynaptic contacts.

Neurological involvement in the respiratory manifestations of COVID-19 patients.

The peculiar features of coronavirus disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), are challenging the current biological knowledge. Early in Feb, 2020, we suggested that SARS-CoV-2 may possess neuroinvasive potential similar to that of many other coronaviruses. Since then, a variety of neurological manifestations have been associated with SARS-CoV-2 infection, which was supported in some patients with neuroimaging and/or cerebrospinal fluid tests. To date, at least 27 autopsy studies on the brains of COVID-19 patients can be retrieved through PubMed/MEDLINE, among which neuropathological alterations were observed in the brainstem in 78 of 134 examined patients, and SARS-CoV-2 nucleic acid and viral proteins were detected in the brainstem in 16/49 (32.7%) and 18/71 (25.3%) cases, respectively. To shed some light on the peculiar respiratory manifestations of COVID-19 patients, this review assessed the existing evidence about the neurogenic mechanism underlying the respiratory failure induced by SARS-CoV-2 infection. Acknowledging the neurological involvement has important guiding significance for the prevention, treatment, and prognosis of SARS-CoV-2 infection.

Evidence of central nervous system infection and neuroinvasive routes, as well as neurological involvement, in the lethality of SARS-CoV-2 infection.

The outbreak of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has become a significant and urgent threat to global health. This review provided strong support for central nervous system (CNS) infection with SARS-CoV-2 and shed light on the neurological mechanism underlying the lethality of SARS-CoV-2 infection. Among the published data, only 1.28% COVID-19 patients who underwent cerebrospinal fluid (CSF) tests were positive for SARS-CoV-2 in CSF. However, this does not mean the absence of CNS infection in most COVID-19 patients because postmortem studies revealed that some patients with CNS infection showed negative results in CSF tests for SARS-CoV-2. Among 20 neuropathological studies reported so far, SARS-CoV-2 was detected in the brain of 58 cases in nine studies, and three studies have provided sufficient details on the CNS infection in COVID-19 patients. Almost all in vitro and in vivo experiments support the neuroinvasive potential of SARS-CoV-2. In infected animals, SARS-CoV-2 was found within neurons in different brain areas with a wide spectrum of neuropathology, consistent with the reported clinical symptoms in COVID-19 patients. Several lines of evidence indicate that SARS-CoV-2 used the hematopoietic route to enter the CNS. But more evidence supports the trans-neuronal hypothesis. SARS-CoV-2 has been found to invade the brain via the olfactory, gustatory, and trigeminal pathways, especially at the early stage of infection. Severe COVID-19 patients with neurological deficits are at a higher risk of mortality, and only the infected animals showing neurological symptoms became dead, suggesting that neurological involvement may be one cause of death.

Trisubstituted alkenes with a single activator as dipolarophiles in a highly diastereo- and enantioselective [3+2] cycloaddition with vinyl epoxides under Pd-catalysis.

1,1,2-Trisubstituted alkenes with a single strongly electronic withdrawing activator, which are unreactive electron-deficient alkenes in transition metal-catalyzed [3+2] cycloaddition with vinyl three-membered heterocycles, were used in the Pd-catalyzed asymmetric cycloaddition of vinyl epoxides, affording multifunctionalized tetrahydrofurans in high yields with high diastereo- and enantioselectivities.

Diastereo- and Enantioselective Palladium-Catalyzed Dearomative [3+2] Cycloaddition of 3-Nitroindoles.

Diastereo- and enantioselective cycloaddition of 3-nitroindoles with vinyl aziridine was realized under Pd-catalysis using commercially available Walphos as the ligand, affording pyrroloindolines in high yields with high diastereo- and enantioselectivities. The reaction can be scaled up to a gram scale and the reaction products are easily converted to amino pyrroloindoline and other pyrroloindoline derivatives.

Highly Diastereo- and Enantioselective Palladium-Catalyzed [3 + 2] Cycloaddition of Vinyl Epoxides and α,ß-Unsaturated Ketones.

An asymmetric [3 + 2] cycloaddition reaction of vinyl epoxides with α,ß-unsaturated ketones, the single activated electron-deficient alkenes, has been achieved under Pd-catalysis in excellent diastereo- and enantioselectivity. The utilities of the protocol are demonstrated by transformation of the products into other useful chiral molecules. Density functional theory calculations rationalize the stereocontrol of the reaction.

Efficient fabrication of high-capacity immobilized metal ion affinity chromatographic media: The role of the dextran-grafting process and its manipulation.

Novel high-capacity Ni(2+) immobilized metal ion affinity chromatographic media were prepared through the dextran-grafting process. Dextran was grafted to an allyl-activated agarose-based matrix followed by functionalization for the immobilized metal ion affinity chromatographic media. With elaborate regulation of the allylation degree, dextran was completely or partly grafted to agarose microspheres, namely, completely dextran-grafted agarose microspheres and partly dextran-grafted ones, respectively. Confocal laser scanning microscope results demonstrated that a good adjustment of dextran-grafting degree was achieved, and dextran was distributed uniformly in whole completely dextran-grafted microspheres, while just distributed around the outside of the partly dextran-grafted ones. Flow hydrodynamic properties were improved greatly after the dextran-grafting process, and the flow velocity increased by about 30% compared with that of a commercial chromatographic medium (Ni Sepharose FF). A significant improvement of protein binding performance was also achieved by the dextran-grafting process, and partly dextran-grafted Ni(2+) chelating medium had a maximum binding capacity for His-tagged lactate dehydrogenase about 2.5 times higher than that of Ni Sepharose FF. The results indicated that this novel chromatographic medium is promising for applications in high-efficiency and large-scale protein purification.

Highly diastereo- and enantioselective palladium-catalyzed [3+2] cycloaddition of vinyl aziridines and α,ß-unsaturated ketones.

A palladium-catalyzed asymmetric [3+2] cycloaddition reaction of vinylaziridines with α,ß-unsaturated ketones, wherein the alkenes have a single activator, is realized in high diastereo- and enantioselectivity, thus affording 3,4-disubstituted pyrrolidines in high yields with excellent ee values. The introduction of a methyl group at C1 of the vinyl group the vinylaziridines greatly improves the stereochemistry of the reaction. A plausible transition state is proposed.