Effect of lactic starter cultures on the organic acid composition of milk and cheese during ripening—analysis by HPLC

The major function of lactic starter cultures in cheese making is to produce lactic and other organic acids from the carbohydrates present in milk. The activity of six starter cultures consisting of two Lactococcus lactis ssp. lactis , two Lactococcus lactis ssp. lactis biovar. diacetylactis and two Leuconostoc strains, was tested by monitoring the evolution of the organic acid composition of milk by a modified HPLC method. In addition, their performance as cheese starters was also tested. The HPLC method developed proved to be a precise tool to monitor the organic acid content. Thus, it can be used to follow the fermentation ability of starter cultures, providing information about the type of fermentation. The use of any of the six starters assayed is suggested for manufacturing Afuega'l Pitu cheese.     

Testis size,epididymis weight,and sperm competition in rhesus macaques

The intensity of sperm competition is often measured using the gonadosomatic index (testes/body weight). But sperm competition could be mediated more by size of the epididymis than by size of the testicles, and little information is available on the relationship between testicular and epididymal size. We found that both organs were positively correlated in size among male rhesus macaques. Body weight accounted for over 70% of the variance in testicle size and volumetric estimates of testicle size accurately reflected testicle weight. We conclude that methods for ascertaining testicle size are accurate, but the covariation in size between testicles and epididymis will hamper understanding of the physiological mechanisms involved in sperm competition in primates. © 1993 Wiley-Liss, Inc.     

Initiation of growth in pbpAts and rodAts mutants of Escherichia coli

Escherichia coli strains harbouring pbpAts mutations are particularly sensitive to functional alterations of penicillin-binding protein 2 (PBP 2) at the initiation of growth. Shift-up to 42 degrees C results in the inability of cells to reach a steady rate of growth and division. Furthermore, a very high proportion of cells generate minicell-like structures which are pinched-off through a process requiring the activity of penicillin-binding protein 3 (PBP 3).     

Hydrogen sulfide:A novel component in Arabidopsis peroxisomes which triggers catalase inhibition

Plant peroxisomes have the capacity to generate different reactive oxygen and nitrogen species(ROS and RNS),such as H_2O_2,superoxide radical(O_2~-),nitric oxide and peroxynitrite(ONOO~-).These organelles have an active nitrooxidative metabolism which can be exacerbated by adverse stress conditions.Hydrogen sulfide(H_2S)is a new signaling gasotransmitter which can mediate the posttranslational modification(PTM)persulfidation.We used Arabidopsis thaliana transgenic seedlings expressing cyan fluorescent protein(CFP)fused to a canonical peroxisome targeting signal 1(PTS1)to visualize peroxisomes in living cells,as well as a specific fluorescent probe which showed that peroxisomes contain H_2S.H_2S was also detected in chloroplasts under glyphosate-induced oxidative stress conditions.Peroxisomal enzyme activities,including catalase,photorespiratory H_2O_2-generating glycolate oxidase(GOX)and hydroxypyruvate reductase(HPR),were assayed in vitro with a H_2S donor.In line with the persulfidation of this enzyme,catalase activity declined significantly in the presence of the H_2S donor.To corroborate the inhibitory effect of H_2S on catalase activity,we also assayed pure catalase from bovine liver and pepper fruit-enriched samples,in which catalase activity was inhibited.Taken together,these data provide evidence of the presence of H_2S in plant peroxisomes which appears to regulate catalase activity and,consequently,the peroxisomal H_2O_2 metabolism.     

Genetic Screens Identify Host Factors for SARS-CoV-2 and Common Cold Coronaviruses

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Bifidobacteria-mediated immune system imprinting early in life

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The synthetic varespladib molecule is a multi-functional inhibitor for PLA2 and PLA2-like ophidic toxins

BackgroundThe treatment for snakebites is early administration of antivenom, which can be highly effective in inhibiting the systemic effects of snake venoms, but is less effective in the treatment of extra-circulatory and local effects. To complement standard-of-care treatments such as antibody-based antivenoms, natural and synthetic small molecules have been proposed for the inhibition of key venom components such as phospholipase A₂ (PLA₂) and PLA₂-like toxins. Varespladib (compound LY315920) is a synthetic molecule developed and clinically tested aiming to block inflammatory cascades of several diseases associated with high PLA₂s. Recent studies have demonstrated this molecule is able to potently inhibit snake venom catalytic PLA₂ and PLA₂-like toxins.MethodsIn vivo and in vitro techniques were used to evaluate the inhibitory effect of varespladib against MjTX-I. X-ray crystallography was used to reveal details of the interaction between these molecules. A new methodology that combines crystallography, mass spectroscopy and phylogenetic data was used to review its primary sequence.ResultsVarespladib was able to inhibit the myotoxic and cytotoxic effects of MjTX-I. Structural analysis revealed a particular inhibitory mechanism of MjTX-I when compared to other PLA₂-like myotoxin, presenting an oligomeric-independent function.ConclusionResults suggest the effectiveness of varespladib for the inhibition of MjTX-I, in similarity with other PLA₂ and PLA₂-like toxins.General significanceVarespladib appears to be a promissory molecule in the treatment of local effects led by PLA₂ and PLA₂-like toxins (oligomeric dependent and independent), indicating that this is a multifunctional or broadly specific inhibitor for different toxins within this superfamily.     

Automated sample preparation and gas chromatographic–mass spectrometric analysis of urinary androgenic anabolic steroids

This paper presents an automated method for extracting anabolic agents from urine samples for their GC–MS analysis by selected-ion monitoring. The sample preparation was carried out in a Hewlett-Packard 7686 SPE PrepStation system. Each 0.6-ml aliquot was hydrolyzed, extracted, dried and trimethylsilyl (TMS) derivatized in a 2-ml vial without any hands-on labor. When sample preparation was finished 2 μl of the extract was injected into the gas chromatograph by split (1:10) mode. Due to the small amount of free space in the 2-ml vials for handling the sample, parameters like time of hydrolysis, type of shaking, number of extractions and some TMS derivatization parameters had to be adjusted to achieve the best recovery for all of the compounds in the screening. Manual and automated sample preparation schemes were compared in terms of linearity, precision, accuracy, limit of detection and recovery data. When large concentrations were analyzed using the automated method no carry-over effect was observed.