Aroid scarabs in the genus Peltonotus Burmeister (Coleoptera,Scarabaeidae, Dynastinae): key to species and new distributional data

The southeast Asian scarab beetle genus Peltonotus Burmeister (Scarabaeidae, Dynastinae, Cyclocephalini) is reviewed. New country records for Peltonotus morio Burmeister (Myanmar and Vietnam), Peltonotus nasutus Arrow (southern China and Cambodia), and Peltonotus favonius Jameson and Wada (Myanmar) are reported, including a new record in the Palearctic/Sino-Japanese biogeographic region. The first female specimen of Peltonotus favonius is described. Biological associations with aroid inflorescences are reviewed, and human consumption of Peltonotus beetles is reported. A key to all species, paralectotype designations for Peltonotus nasutus, diagnoses, and distributions using dynamic mapping tools are included.     

Probing the substrate specificity of the intracellular brain platelet-activating factor acetylhydrolase.

Platelet-activating factor acetylhydrolases (PAF-AHs) are unique PLA2s which hydrolyze the sn-2 ester linkage in PAF-like phospholipids with a marked preference for very short acyl chains, typically acetyl. The recent solution of the crystal structure of the alpha(1) catalytic subunit of isoform Ib of bovine brain intracellular PAF-AH at 1.7 A resolution paved the way for a detailed examination of the molecular basis of substrate specificity in this enzyme. The crystal structure suggests that the side chains of Thr103, Leu48 and Leu194 are involved in substrate recognition. Three single site mutants (L48A, T103S and L194A) were overexpressed and their structures were solved to 2.3 A resolution or better by X-ray diffraction methods. Enzyme kinetics showed that, compared with wild-type protein, all three mutants have higher relative activity against phospholipids with sn-2 acyl chains longer than an acetyl. However, for each of the mutants we observed an unexpected and substantial reduction in the V(max) of the reaction. These results are consistent with the model in which residues Leu48, Thr103 and Leu194 indeed contribute to substrate specificity and in addition suggest that the integrity of the specificity pocket is critical for the expression of full catalytic function, thus conferring very high substrate selectivity on the enzyme.     

Encapsulation of interleukin-2 in murine erythrocytes and subsequent deposition in mice receiving a subcutaneous injection

Radiolabeled recombinant human interleukin-2 (IL-2) was successfully encapsulated in both mouse and sheep erythrocytes. Of the added IL-2, 70% was recovered bound to or encapsulated within the carrier cells. Erythrocytes containing IL-2 were stable in vitro and most of the IL-2 remained associated with the cells following a 16-h incubation at 37 degrees C. When carrier erythrocytes containing IL-2 were injected subcutaneously into mice, intact [35S]IL-2 was detectable in a number of tissues 3 days after injection.     

Duplications of the X chromosome in males: evidence that most parts of the X chromosome can be active in two copies

Summary We have analysed two duplications of the X chromosome in male patients using chromosome replication and DNA methylation patterns as determinants of the functional status of the duplicated segments. In both cases, the large duplicated regions, Xq12-q22 and Xq26.3-qter, were not inactivated. A review of previously reported male cases revealed that these duplications were also not subject to inactivation. Taken together, the examined duplications cover almost the entire X chromosome except the pericentromeric region and Xq25–26. Thus, most regions of the X chromosome can be present in two functional copies without lethal consequences.     

A continuous-flow high-yield process for preparation of lipid-free hemoglobin

Hypotonic hollow-fiber dialysis of bovine red blood cells followed by ultrafiltration through 0.1-micron pore hollow fibers provides a simple method for isolation of lipid-free hemoglobin. Hemoglobin (Hb) isolated by comparative techniques were all contaminated with membrane stroma. HPLC analysis of Hb revealed a protein peak of 99.6% purity and sodium dodecylsulfate-polyacrylamide gel electrophoresis analysis revealed a single band. The process requires hypoosmotic dialysis of bovine RBC to a final 160-180 mosmol/kg osmotic pressure. Additional reduction in osmotic pressure causes irreversible cell lysis which leads to lipid contamination of the Hb. Processing of 1/2 liter of packed red blood cells requires 4-5 h, resulting in an average of 90% hemoglobin recovery.     

An evaluation of Ficoll density gradient centrifugation as a method for eliminating microbial contamination and purifying plant protoplasts

Ficoll density gradient centrifugation was used to generate sterile protoplasts from non-sterile Pteridium cultures. The method was found to drastically reduce levels of fungal and bacterial contamination introduced prior to centrifugation whilst concentrating and purifying protoplasts.     

Emergence of flat cells from glia in stationary cultures of embryonic chick neural retina

Summary When embryonic retina is dissociated into a single cell suspension and maintained in stationary culture, a population of flat cells is found on the culture dish. We have carried out a morphologic and immunologic study of the emergence of this population in vitro. Ten- and fourteen-day-old chick embryo retinas were dissociated with trypsin, seeded on glass cover slips for various times, and prepared for scanning electron microscopy (SEM) and immunofluorescence (IF) for Vimentin, an intermediate filament protein. SEM indicates that the characteristic flat cell morphology is initiated in some cells in as little as 30 min after the start of the culture. Not all of the cells that attach flatten. As incubation proceeds, small clusters of cells that had formed in suspension attach to the substrate, and flat cells emerge from them. The flattened cells are positive for Vimentin by IF within 10 min of attachment. The percent of fluorescent cells found on the substrate is constant during the time in culture. This suggests that flat cells do not attach first, followed by neural cells, but that the neural cells and flat cells attach to the dish at the same rate. When aggregates that had formed in suspension attach to the substrate, they are anchored by flat cells that migrate out of the aggregate. Since Vimentin appears in the cultured cells within 10 min, it is unlikely that it has been newly synthesized. Thus, the same cells that contained Vimentin in the retina now express it as flat cells. this supports the hypothesis that flat cells derive from the same cells in the retina that give rise to Müller cells. We have also observed the emergence of a population of cells with short (0.5μm) microvilli that appear within 8 h of culture. They seem to be a distinct subpopulation of the cells on the upper portion of attached clusters. This research was supported in part by grant EY-04892 and RR-0715 from the National Institutes of Health, Bethesda, MD, and a grant from the W.W. Smith Foundations     

Dust and ammonia in horse stalls with different ventilation rates and bedding

Airborne particles and ammonia were monitored in horse stalls managed under four conditions. Two ventilation rates, high (27 air changes per h) and low (5 air changes per h) and two bedding types, paper and straw, were employed. At both ventilation rates, the number of airborne particles generated while the stalls were mucked out was higher with straw than with paper. Particles were more efficiently cleared at the higher ventilation rate in both the straw and paper stalls. Ammonia measurements reflected an accumulation over time. In the stalls with low ventilation, ammonia levels were significantly higher than in those stalls with high ventilation regardless of bedding type. Management decisions and their relationships to respiratory disorders are discussed.