Tris(2,2′-bipyridine)ruthenium(II) as a peroxide-producing replacement for enzymes as chemical labels

The concentration of the ruthenium-based label is determined from the rate of hydrogen peroxide production elicited by photolysis. Electron transfer quenching of the photoexcited label by methyl viologen (1,1′-dimethyl-4,4′-bipyridinium dication, MV²⁺) and/or oxygen in the presence of EDTA generates hydrogen peroxide. Both flow injection and direct photolysis techniques were tested, with the latter showing better results. Direct photolysis is more sensitive, faster, requires only a 20 μl sample volume, uses only 30 mW laser power and shows a smaller background. The presence of 5% normal human serum in the sample did not interfere with the measurements. Linear calibration curves were obtained in the nanomolar concentration range for goat antimouse antibody labeled with the ruthenium complex. The determination of membrane-surface-bound labeled IgG is accomplished by direct photolysis of a membrane that covers a platinum microelectrode.     

Simplification and standardization of dot-ELISA for human schistosomiasis mansoni

Dot-ELISA, a technique that shares the same principles as the enzyme immunoassay, is useful for detection of anti-Schistosoma mansoni antibodies in the sera of patients with Schistosoma mansoni infections. The antigens were fixed to the nitrocellulose strips, blocked with 1% bovine serum albumin in 0.05% Tween 20. Patient sera (40) and normal laboratory personnel sera (9) were applied to the sheet directly, without cutting the strips into small discs. The nitrocellulose sheets are kept in a humid chamber for 30 min and then washed. After incubation with peroxidase-conjugated goat anti-human antibody, washing, and addition of substrate, positive reactions appear as brown dots against the white background. The room temperature assay takes about 2 hr. The optimum antigen concentration is 20-80 ng per dot and the optimum serum dilution is 1:100-1:400. The sensitivity and specificity of the assay are 90-95% and 90%, respectively. The level of positivity of the dot-ELISA by an arbitrary scale compares with standard micro-ELISA. The single positive reaction in a normal serum sample in dot-ELISA is also positive in micro-ELISA. Cross-reactivity between the S. mansoni antigen and human fascioliasis sera was noticed in 2 out of 8 patient sera. Good correlation between the arbitrary level of dot-ELISA and the absorbance of standardized micro-ELISA shows that the dot-ELISA is useful both for laboratory and field studies.     

The murine homeo box gene product, Hox 1.1 protein, is growth-controlled and associated with chromatin

In order to gain insight into the function of the Hox 1.1 gene, we studied the expression of the murine homeo box gene product, the Hox 1.1 protein. Monoclonal antibodies were raised against synthetic peptides of the Hox 1.1 protein to study the localization and expression pattern of this protein under various culture conditions. By means of indirect immunofluorescence we localized the Hox 1.1 protein to the nucleus in differentiated F9 and NIH 3T3 cells. During mitosis the protein was found to be associated with chromatin. Confluent NIH 3T3 cells harbored little if any Hox 1.1 protein. After "wounding" the cells in this confluent monolayer, we observed an induction of the expression of the Hox 1.1 protein. However, addition of insulin to F9 and contact-inhibited NIH 3T3 cells led to an increase of the Hox 1.1 RNA and protein expression. Thus, the induction of the Hox 1.1 protein is associated not only with the differentiation of embryonal carcinoma (EC) cells, but may also correlate with stages of cell growth.     

Waterlogging injury in sorghum seedlings and their kinetin effected rapid recovery

Short term waterlogging affected the growth of sorghum seedlings as indicated by a high mortality rate of the seedlings and a decrease in the shoot and root biomass, net assimilation rate (NAR), leaf area ratio (LAR), relative growth rate (RGR), total photosynthetic area and rate of photosynthesis. Plant resistance to the stress was exhibited by decreased stomatal index (SI), rate of transpiration and rate of respiration. When the stressed plants were exposed to normal conditions, the recovery of the seedlings was rapid and was enhanced by foliar application of kinetin at 5 mgl^-1.     

Staining Glycol Methacrylate Embedded Cartilage with Triethyl-Carbocyanin Dbtc (“Ethyl-Stains All”) With Special Reference to the Interlacunar Network

The dye, triethyl-carbocyanin DBTC, was tested for differential staining of cartilage structures. Femoral head articular cartilage from neonatal rats was processed for histology to demonstrate the interlacunar network. Sections of glycol methacrylate (GMA) embedded cartilage were stained at pH 2.8, 5.4, 6.1 and 8.0 to determine the optimal staining conditions. Only at pH 6.1 were all cartilage structures stained and the best contrast achieved. Streptomyces hyaluronidase, chondroitinase ABC, pepsin, trypsin, and pronase digestions were carried out prior to staining at pH 6.1 to evaluate the selectivity of the stain. Undigested chondrocyte nuclear chromatin stained dark purple; staining intensity was reduced slightly by pepsin or trypsin digestion. Undigested chondrocyte cytoplasm stained light blue but stained purple after hyaluronidase digestion. Undigested extracellular matrix stained light violet; staining was almost entirely eliminated by chondroitinase ABC digestion, was unaffected by hyaluronidase, and was either unaffected or increased after proteinase digestion. Staining of a narrow zone of matrix adjacent to the network was prevented by proteinase digestion while the network element appeared as a thin dark line. The network appears to be a trilaminar structure; a core element of hyaluronic acid and protein surrounded by a protein sheath. Triethyl-carbocyanin DBTC staining of cartilage offers slightly more selectivity and contrast than methylene blue, toluidine blue or safranin O. At pH 6.1, DNA, perhaps RNA, and hyaluronic acid stained deep purple; chondroitin sulfate, light violet; protein (collagen), stained very light violet if at all.     

High-frequency Organogenesis from Direct Seed Culture in Lathyrus

Culture conditions were developed for inducing a high frequencyof direct shoot morphogenesis and whole plant regeneration incultures of intact seedlings of Lathyrus cicera L., L. ochrus(L.) DC., L. sativus L., and L. tingitanus L. The procedureof shoot regeneration involved culturing of whole, mature seedson MS medium containing cytokinins, or thidiazuron (TDZ), asubstituted phenylurea with cytokinin-like activity. Differentiationof shoots occurred without an intervening callus phase fromthe cotyledonary node and surrounding tissues of the intactseedlings developed from seeds germinated on media containingkinetin, BAP or TDZ. An average of 19·0, 15·8,28·8 and 43·0 shoots were regenerated at optimalconcentrations of 50·0, 50·0 and 80·0 µMBAP in L. cicera, L. tingitanus, L. ochrus and L. sativus, respectively.TDZ enhanced the shoot formation at the concentration of 10µM to an average of 33·1 and 33·7 shootsper seedling in L. cicera and L. tingitanus and at 50 µM,to 57·4 shoots per seedling in L. sativus. Regeneratedshoots developed roots on a modified MS medium containing 2·5µM NAA and the surviving plantlets were transferred tosoil. Histological studies revealed de novo formation of shoot budsfrom the epidermal or subepidermal cells of the basal and nodalregion of multiple epicotyls. Several meristematic centres consistingof actively-dividing cells developed in the subepidermal celllayer of the nodal tissue and adjacent areas within 7 d of seedculture on a cytokinin- or TDZ-supplemented medium. The patternof the development of these meristematic centres and shoot developmentwas similar in all four species.Copyright 1993, 1999 AcademicPress Seed culture, direct shoot morphogenesis, Lathyrus, thidiazuron, grass pea, vetch ochrus     

A Comparison of Four Vocalizations of the Genus Tragopan (Aves,Phasianidae)

Four calls of the genus Tragopan were described and acoustically analysed. Alarm and wing whir calls were very similar in sound and structure in all five species. By contrast, a comparison of 11 physical parameters of advertisement and clicking calls indicated that species separated into three groups: western and Cabot's each separated into their own group, whereas Blyth's, Temminck's and satyr formed another group. It was hypothesized that the tragopan prototype population had their origin in the eastern Himalayas. Thus, the centrally distributed species of tragopans (satyr, Blyth's and Temminck's) retained characteristics of the ancestral population, whereas the peripheral species (western and Cabot's) underwent vocal modifications. Courtship vocalizations, which are under sexual selection pressure, probably serve as species-isolating mechanisms in sympatric species.     

Disasters collide at the intersection of extreme weather and infectious diseases

Natural disasters interact to affect the resilience and prosperity of communities and disproportionately affect low income families and communities of colour. However, due to lack of a common theoretical framework, these are rarely quantified. Observing severe weather events (e.g. hurricanes and tornadoes) and epidemics (e.g. COVID-19) unfolding in southeastern US communities led us to conjecture that interactions among catastrophic disturbances might be much more considerable than previously recognized. For instance, hurricane evacuations increase human aggregation, a factor that affects the transmission of acute infections like SARS-CoV-2. Similarly, weather damage to health infrastructure can reduce a community's ability to provide services to people who are ill. As globalization and human population and movement continue to increase and weather events are becoming more intense, such complex interactions are expected to magnify and significantly impact environmental and human health.     

Silicon Enhances Morpho–Physio–Biochemical Responses in Arsenic Stressed Spinach (Spinacia oleracea L.) by Minimizing Its Uptake

Journal of Plant Growth Regulation - Soil contamination with toxic heavy metals [such as arsenic (As)] is becoming a serious global problem due to rapid development of social economy. Silicon (Si),...