Global stability in a class of prey-predator models

Global stability is established in a class of prey-predator models. This includes a prey-predator model in which the predator has Type 2 functional response and no intraspecific interactions. Two simple examples demonstrate that Kolmogoroff’s theorem does not apply to some members of this class of models.     

Structural and functional domains in human tumour necrosis factors.

Human tumour necrosis factors (hTNFs) alpha and beta are related pleiotropic cytokines which share many activities and compete with each other for binding to two receptor components on many cell types. Although structural and biological data indicate that the active form of hTNF-alpha may be a symmetrical trimer, the manner in which hTNFs interact with their receptors to trigger a myriad of cell type-dependent responses is not clear. A combination of chemical modification, epitope mapping and site-directed mutagenesis approaches suggest that at least four distinct peptide sequences are important for the biological activity of hTNF-alpha. In particular, certain peptide sequences between amino acid positions 11 and 35 in hTNF-alpha appear to be critical for receptor binding and triggering biological responses. The recent cloning of the two hTNF-alpha/beta receptors opens the way for precise mapping of the functional domains in hTNFs.     

Protein replenishment in pitcher fluids of Nepenthes × ventrata revealed by quantitative proteomics (SWATH-MS) informed by transcriptomics

Journal of Plant Research - Carnivorous plants capture and digest insects for nutrients, allowing them to survive in soil deprived of nitrogenous nutrients. Plants from the genus Nepenthes produce...     

Alternative Fecal Indicators and Their Empirical Relationships with Enteric Viruses,Salmonella enterica,and Pseudomonas aeruginosa in Surface Waters of a Tropical Urban Catchment

The suitability of traditional microbial indicators (i.e., Escherichia coli and enterococci) has been challenged due to the lack of correlation with pathogens and evidence of possible regrowth in the natural environment. In this study, the relationships between alternative microbial indicators of potential human fecal contamination (Bacteroides thetaiotaomicron, Methanobrevibacter smithii, human polyomaviruses [HPyVs], and F+ and somatic coliphages) and pathogens (Salmonella spp., Pseudomonas aeruginosa, rotavirus, astrovirus, norovirus GI, norovirus GII, and adenovirus) were compared with those of traditional microbial indicators, as well as environmental parameters (temperature, conductivity, salinity, pH, dissolved oxygen, total organic carbon, total suspended solids, turbidity, total nitrogen, and total phosphorus). Water samples were collected from surface waters of urban catchments in Singapore. Salmonella and P. aeruginosa had significant positive correlations with most of the microbial indicators, especially E. coli and enterococci. Norovirus GII showed moderately strong positive correlations with most of the microbial indicators, except for HPyVs and coliphages. In general, high geometric means and significant correlations between human-specific markers and pathogens suggest the possibility of sewage contamination in some areas. The simultaneous detection of human-specific markers (i.e., B. thetaiotaomicron, M. smithii, and HPyVs) with E. coli and enterococcus supports the likelihood of recent fecal contamination, since the human-specific markers are unable to regrow in natural surface waters. Multiple-linear-regression results further confirm that the inclusion of M. smithii and HPyVs, together with traditional indicators, would better predict the occurrence of pathogens. Further study is needed to determine the applicability of such models to different geographical locations and environmental conditions.     

The application of spectroscopy techniques for diagnosis of malaria parasites and arboviruses and surveillance of mosquito vectors: A systematic review and critical appraisal of evidence

Spectroscopy-based techniques are emerging diagnostic and surveillance tools for mosquito-borne diseases. This review has consolidated and summarised recent research in the application of Raman and infrared spectroscopy techniques including near- and mid-infrared spectroscopy for malaria and arboviruses, identified knowledge gaps, and recommended future research directions. Full-length peer-reviewed journal articles related to the application of Raman and infrared (near- and mid-infrared) spectroscopy for malaria and arboviruses were systematically searched in PUBMED, MEDILINE, and Web of Science databases using the PRISMA guidelines. In text review of identified studies included the methodology of spectroscopy technique used, data analysis applied, wavelengths used, and key findings for diagnosis of malaria and arboviruses and surveillance of mosquito vectors. A total of 58 studies met the inclusion criteria for our systematic literature search. Although there was an increased application of Raman and infrared spectroscopy-based techniques in the last 10 years, our review indicates that Raman spectroscopy (RS) technique has been applied exclusively for the diagnosis of malaria and arboviruses. The mid-infrared spectroscopy (MIRS) technique has been assessed for the diagnosis of malaria parasites in human blood and as a surveillance tool for malaria vectors, whereas the near-infrared spectroscopy (NIRS) technique has almost exclusively been applied as a surveillance tool for malaria and arbovirus vectors.Conclusions/SignificanceThe potential of RS as a surveillance tool for malaria and arbovirus vectors and MIRS for the diagnosis and surveillance of arboviruses is yet to be assessed. NIRS capacity as a surveillance tool for malaria and arbovirus vectors should be validated under field conditions, and its potential as a diagnostic tool for malaria and arboviruses needs to be evaluated. It is recommended that all 3 techniques evaluated simultaneously using multiple machine learning techniques in multiple epidemiological settings to determine the most accurate technique for each application. Prior to their field application, a standardised protocol for spectra collection and data analysis should be developed. This will harmonise their application in multiple field settings allowing easy and faster integration into existing disease control platforms. Ultimately, development of rapid and cost-effective point-of-care diagnostic tools for malaria and arboviruses based on spectroscopy techniques may help combat current and future outbreaks of these infectious diseases.     

Rapid selection of potyviral cross-protection effective mutants from the local lesion host after nitrous acid mutagenesis

Zucchini yellow mosaic virus (ZYMV) seriously damages cucurbits worldwide. Control of ZYMV by cross-protection has been practised for decades, but selecting useful mild viruses is time-consuming and laborious. Most attenuated potyviruses used for cross-protection do not induce hypersensitive reaction (HR) in Chenopodium quinoa, a local lesion host Chenopodium quinoa. Here, severe ZYMV TW-TN3 tagged with green fluorescent protein (GFP), designated ZG, was used for nitrous acid mutagenesis. From three trials, 11 mutants were identified from fluorescent spots without HR in inoculated C. quinoa leaves. Five mutants caused attenuated symptoms in squash plants. The genomic sequences of these five mutants revealed that most of the nonsynonymous changes were located in the HC-Pro gene. The replacement of individual mutated HC-Pros in the ZG backbone and an RNA silencing suppression (RSS) assay indicated that each mutated HC-Pro is defective in RSS function and responsible for reduced virulence. Four mutants provided high degrees of protection (84%–100%) against severe virus TW-TN3 in zucchini squash plants, with ZG 4-10 being selected for removal of the GFP tag. After removal of the GFP gene, Z 4-10 induced symptoms similar to ZG 4-10 and still provided 100% protection against TW-TN3 in squash, thus is considered not a genetically engineered mutant. Therefore, using a GFP reporter to select non-HR mutants of ZYMV from C. quinoa leaves is an efficient way to obtain beneficial mild viruses for cross-protection. This novel approach is being applied to other potyviruses.     

The effect of submandibular gland removal on testicular and epididymal parameters

The effect of sialoadenectomy (submandibular gland removal) for four weeks duration was studied in five C3H mice and four sham-operated controls. This preliminary experiment using small numbers of animals indicated that sperm production parameters were lowered in sialoadenectomized animals although there were no significant differences between the sialodenectomized and sham-operated group. In a second experiment using larger numbers of animals, significant differences in testicular weights, epididymal weights, and testis weights were noted. These parameters were reduced only 10-14% from control levels. Epididymal sperm head counts were reduced 10% after sialoadenectomy but the two groups were not significantly different (P less than 0.05). No difference in testicular histology was observed. The present report contrasts to that of Tsutsumi et al. (1986) who indicate that submandibular removal with subsequent depletion of epidermal growth factor (EGF), is extremely deleterious (40-55% decreases in spermatid and sperm content) to the progress spermatogenesis.