beta-Glucans in promoting health: prevention against mutation and cancer

The polysaccharides beta-glucans occur as a principal component of the cellular walls. Some microorganisms, such as yeast and mushrooms, and also cereals such as oats and barley, are of economic interest because they contain large amounts of beta-glucans. These substances stimulate the immune system, modulating humoral and cellular immunity, and thereby have beneficial effect in fighting infections (bacterial, viral, fungal and parasitic). beta-Glucans also exhibit hypocholesterolemic and anticoagulant properties. Recently, they have been demonstrated to be anti-cytotoxic, antimutagenic and anti-tumorogenic, making them promising candidate as pharmacological promoters of health.     

Assessing the impact of rumen microbial communities on methane emissions and production traits in Holstein cows in a tropical climate

The evaluation of how the gut microbiota affects both methane emissions and animal production is necessary in order to achieve methane mitigation without production losses. Toward this goal, the aim of this study was to correlate the rumen microbial communities (bacteria, archaea, and fungi) of high (HP), medium (MP), and low milk producing (LP), as well as dry (DC), Holstein dairy cows in an actual tropical production system with methane emissions and animal production traits. Overall, DC cows emitted more methane, followed by MP, HP and LP cows, although HP and LP cow emissions were similar. Using next-generation sequencing, it was found that bacteria affiliated with Christensenellaceae, Mogibacteriaceae, S24-7, Butyrivibrio, Schwartzia, and Treponema were negatively correlated with methane emissions and showed positive correlations with digestible dry matter intake (dDMI) and digestible organic matter intake (dOMI). Similar findings were observed for archaea in the genus Methanosphaera. The bacterial groups Coriobacteriaceae, RFP12, and Clostridium were negatively correlated with methane, but did not correlate with dDMI and dOMI. For anaerobic fungal communities, no significant correlations with methane or animal production traits were found. Based on these findings, it is suggested that manipulation of the abundances of these microbial taxa may be useful for modulating methane emissions without negatively affecting animal production.     

Nisin Resistance of Streptococcus bovis

The growth of Streptococcus bovis JB1 was initially inhibited by nisin (1 μM), and nisin caused a more than 3-log decrease in viability. However, some of the cells survived, and these nisin-resistant cells grew as rapidly as untreated ones. To see if the nisin resistance was merely a selection, nisin-sensitive cells were obtained from agar plates lacking nisin. Results indicated that virtually any nisin-sensitive cell could become nisin-resistant if the ratio of nisin to cells was not too high and the incubation period was long enough. Isolates obtained from the rumen were initially nisin sensitive, but they also developed nisin resistance. Nisin-resistant cultures remained nisin resistant even if nisin was not present, but competition studies indicated that nisin-sensitive cells could eventually displace the resistant ones if nisin was not present. Nisin-sensitive, glucose-energized cells lost virtually all of their intracellular potassium if 1 μM nisin was added, but resistant cells retained potassium even after addition of 10 μM nisin. Nisin-resistant cells were less hydrophobic and more lysozyme-resistant than nisin-sensitive cells. Because the nisin-resistant cells bound less cytochrome c, it appeared that nisin was being excluded by a net positive (i.e., less negative) charge. Nisin-resistant cells had more lipoteichoic acid than nisin-sensitive cells, and deesterified lipoteichoic acids from nisin-resistant cells migrated more slowly through a polyacrylamide gel than those from nisin-sensitive cells. These results indicated that lipoteichoic acids could be modified to increase the resistance of S. bovis to nisin. S. bovis JB1 cultures were still sensitive to monensin, tetracycline, vancomycin, and bacitracin, but ampicillin resistance was 1,000-fold greater.     

Immune response in COVID-19: what is next?

The coronavirus disease 2019 (COVID-19) has been a global pandemic for more than 2 years and it still impacts our daily lifestyle and quality in unprecedented ways. A better understanding of immunity and its regulation in response to SARS-CoV-2 infection is urgently needed. Based on the current literature, we review here the various virus mutations and the evolving disease manifestations along with the alterations of immune responses with specific focuses on the innate immune response, neutrophil extracellular traps, humoral immunity, and cellular immunity. Different types of vaccines were compared and analyzed based on their unique properties to elicit specific immunity. Various therapeutic strategies such as antibody, anti-viral medications and inflammation control were discussed. We predict that with the available and continuously emerging new technologies, more powerful vaccines and administration schedules, more effective medications and better public health measures, the COVID-19 pandemic will be under control in the near future. Subject terms: Infectious diseases, Antimicrobial responses     

Mechanical and biological performances of new scaffolds made of collagen hydrogels and fibroin microfibers for vascular tissue engineering

A microstructured composite material made of collagen hydrogel (matrix) and silk fibroin microfibers (randomly oriented reinforcing fibers) is investigated in order to conjugate the mechanical resistance of fibroin with the suitable biological performance of collagen to design new scaffolds for vascular tissue engineering. Results show that fibroin microfibers and collagen fibrils have suitable interfacial adhesion, and the scaffold exhibits improved mechanical properties if compared with a pure collagen hydrogel. Furthermore, the overall biological performance is improved.     

A protein factor binding to an octamer motif in the gamma-globin promoter disappears upon induction of differentiation and hemoglobin synthesis in K562 cells.

Using the electrophoretic mobility shift assay and the footprinting technique, we studied the binding of nuclear proteins from erythroid and non erythroid human cells to the promoter region of the human gamma-globin gene. Two regions (A and B) of the promoter are bound by proteins present in uninduced K562 cells, but not in induced K562 cells nor in fetal liver erythroblasts; a protein binding to region A is also present in a variety of lymphoid and myeloid cells. Region B is centered on an octamer sequence identical to that present in immunoglobulin promoter and enhancers and other eukaryotic promoters; a B region binding protein common to K562 and other cells efficiently binds the octamer containing region of the histone H2B gene, while different B region proteins are more specific for uninduced K562 cells and the gamma-globin octamer containing fragment. The possible role of these nuclear proteins in gamma-globin gene regulation and/or cell differentiation is discussed.     

The effects of once or twice daily injections of pFSH on superovulatory response in heifers

Follicle stimulating hormone (FSH) is a glycoprotein hormone with a short half-life and has to be given twice daily for 3-4 days to induce superovulation in heifers. Since such a regimen is time consuming we compared the ovulatory response and yield of embryos in heifers following superovulation with either once or twice daily injections of pFSH for 4 days during the mid-luteal phase of a synchronized estrous cycle or during a prolonged luteal phase in heifers which had been immunized against prostaglandin F2alpha (PG). In Experiment 1, crossbred heifers (n = 42) previously actively immunized against a PG immunogen were superovulated in a 2 (cyclic or persistent corpus luteum) x 2 (once or twice daily injection) factorial plan. The heifers were superovulated with 75 units pFSH, which was injected subcutaneously once (22.5, 22.5, 15 and 15 units per day) or twice daily (9.3 units per injection) for 4 days. In Experiment 2, cyclic crossbred beef heifers (n = 80) were superovulated using pFSH which was given randomly to heifers once daily subcutaneously (T1) or twice daily intramuscularly (T2) using the same daily dose of 9, 7, 5, and 3 mg per day. Estrus was induced in all heifers in both experiments using 500 mug and 250 mug Cloprostenol 12 hours apart on the third day of pFSH injections. All heifers were inseminated twice with frozen-thawed semen at 12 and 24 hours after the onset of standing estrus or at 56 and 72 hours after the first PG if estrus was not observed. Embryos were recovered at slaughter and graded on a scale of 1 to 5 (1 = excellent, 5 = degenerated). Data were recorded for the number of corpora lutea (CL), large (>/=10 mm) and medium (5-9 mm) follicles, number of embryos recovered and embryo morphology. Data were analyzed by least squares analysis of variance procedures. In Experiment 1, there was no difference in ovulation rate between main effects. Fewer embryos were recovered from heifers with a persistent corpus luteum (pCL) and injected once daily (1.71+/-.75 vs 5.75+/-1.27) than from any other group. Heifers with pCL yielded lower (P < 0.05) numbers of freezable embryos than cyclic animals, regardless of injection regimen. In Experiment 2, T2 heifers had a significantly higher number of CL (16.4+/-1.7 vs 7.7+/-1.7; P = 0.0003), large follicles (4.1+/-0.5 vs 2.8+/-0.5; P = 0.04), medium follicles (6.4+/-0.7 vs 4.4+/-0.7; P = 0.04), embryos recovered (9.6+/-1.1 vs 4.9+/-1.1; P = 0.0025) and freezable embryos (4.7+/-0.7 vs 2.1+/-0.7; P = 0.014) than T1 heifers. It is concluded that a single daily subcutaneous injection of pFSH results in a lower superovulatory response than the twice daily regimen in heifers.     

Production and identification of natural monocyte chemotactic protein from virally infected murine fibroblasts. Relationship with the product of the mouse competence (JE) gene

Primary cultures of mouse embryonic fibroblasts and confluent monolayers of mouse fibroblastoid cells (L929) were found to secrete a chemotactic factor specific for monocytes. It biological activity was deduced from both the migration distance under agarose and the number of migrated monocytes in the micropore filter method. The monocyte chemotactic protein (MCP) was inducible in these cells by double-stranded RNA and by infection with virus. In embryonic fibroblasts MCP was also produced in response to the cytokines interleukin-1 (IL-1) and tumor necrosis factor (TNF). Under all conditions for induction of MCP tested no production of chemotactic activity for granulocytes could be detected. MCP activity from virally infected L929 cells was concentrated and purified by sequential adsorption to controlled pore glass, heparin-Sepharose chromatography, ion-exchange FPLC and reversed-phase HPLC. Pure MCP was found to occur mainly as a 7-8-kDa protein. Although the mature protein possessed a blocked NH2-terminus, it was identified by enzymatic cleavage and sequence analysis of an internal fragment. The sequence obtained corresponded to a part of the cDNA-derived protein sequence of the murine 'competence' (JE) gene, inducible in fibroblasts by cytokines and virus. In all probability the 7-8-kDa MCP form represents the natural product of the mouse gene JE. Murine MCP can thus be classified in the novel family of small inducible inflammatory proteins.