Silencing of cytosolic NADP+-dependent isocitrate dehydrogenase by small interfering RNA enhances the sensitivity of HeLa cells toward staurosporine

Staurosporine induces the production of reactive oxygen species, which play an important causative role in apoptotic cell death. Recently, it was demonstrated that the control of cellular redox balance and the defense against oxidative damage is one of the primary functions of cytosolic NADP⁺-dependent isocitrate dehydrogenase (IDPc) by supplying NADPH for antioxidant systems. The present report shows that silencing of IDPc expression in HeLa cells greatly enhances apoptosis induced by staurosporine. Transfection of HeLa cells with an IDPc small interfering RNA (siRNA) markedly decreased activity of IDPc, enhancing the susceptibility of staurosporine-induced apoptosis reflected by DNA fragmentation, cellular redox status and the modulation of apoptotic marker proteins. These results indicate that IDPc may play an important role in regulating the apoptosis induced by staurosporine and the sensitizing effect of IDPc siRNA on the apoptotic cell death of HeLa cells offers the possibility of developing a modifier of cancer chemotherapy.     

Spatiotemporal distribution and the passive dispersal of fungal spores through HVAC systems

Heating, ventilation and air conditioning (HVAC) systems are widely used to regulate indoor temperature and air quality of modern buildings. The central supply and exhaust system cause the dispersal and removal of bioaerosols. This study presents results from ex situ experiments conducted to a better understanding of the spatiotemporal distribution, passive dispersal and removal of fungal spores through HVAC systems. The study was conducted in a 50 square meters by 3 m high instrument room in a research building with HVAC systems. Plates with Aspergillus flavus colony were attached upside down on the edge of the ceiling vent to imitate the mildew growing. Fungal spores were released for 10 min, collected and counted by the settle plate method in 2 h. Results show that A. flavus spores dispersed to 3.6 m in 2 min and were evenly distributed in the room within 8 min. The concentration of spores decreased from 48 to 3–6 CFU/plate after 60 min and was lower than 1% after 120 min. Our results suggest that airborne fungal spores disperse and remove by HVAC systems efficiently. Without the external and internal source, the HVAC system could greatly reduce the fungal amount in the indoor air to the background level within one hour. This study provided the observed data of the transmission and retention of internal or external biological contaminants through HVAC system.

     

Three new species of the genus Probles F?rster (Hymenoptera,Ichneumonidae, Tersilochinae) from?South Korea

Three closely related species of the genus Probles Förster, P. fulgida sp. n., P. korusa sp. n. and P. rukora sp. n., belong to the subgenus Euporizon Horstmann and differ from other Palearctic species of the genus by a combination of long and apically weakly sinuate ovipositor and short temple. These three species are assigned to a newly designated fulgida species-group, and a portion of the key for identification of this species-group is provided. Based on the shape of the ovipositor apex, the fulgida species-group resemble members of the subgenus Microdiaparsis Horstmann but are distinct in having a much shorter temple.     

Lagging strand synthesis in coordinated DNA synthesis by bacteriophage t7 replication proteins

The proteins of bacteriophage T7 DNA replication mediate coordinated leading and lagging strand synthesis on a minicircle template. A distinguishing feature of the coordinated synthesis is the presence of a replication loop containing double and single-stranded DNA with a combined average length of 2600 nucleotides. Lagging strands consist of multiple Okazaki fragments, with an average length of 3000 nucleotides, suggesting that the replication loop dictates the frequency of initiation of Okazaki fragments. The size of Okazaki fragments is not affected by varying the components (T7 DNA polymerase, gene 4 helicase-primase, gene 2.5 single-stranded DNA binding protein, and rNTPs) of the reaction over a relatively wide range. Changes in the size of Okazaki fragments occurs only when leading and lagging strand synthesis is no longer coordinated. The synthesis of each Okazaki fragment is initiated by the synthesis of an RNA primer by the gene 4 primase at specific recognition sites. In the absence of a primase recognition site on the minicircle template no lagging strand synthesis occurs. The size of the Okazaki fragments is not affected by the number of recognition sites on the template.     

Characterizing man-made and natural modifications of microbial diversity and activity in coastal ecosystems

The impacts of growing coastal pollution and habitat alteration accompanying human encroachment are of great concern at the microbial level, where much of the ocean's primary production and biogeochemical cycling takes place. Coastal ecosystems are also under the influence of natural perturbations such as major storms and flooding. Distinguishing the impacts of natural and human stressors is essential for understanding environmentally-induced change in microbial diversity and function. The objective of this paper is to discuss the applications and merits of recently developed molecular, ecophysiological and analytical indicators and their utility in examining anthropogenic and climatic impacts on the structure and function of coastal microbial communities. The nitrogen-limited Neuse River Estuary and Pamlico Sound, North Carolina are used as examples of ecosystems experiencing both anthropogenic (i.e., accelerating eutrophication) and climatic stress (increasing frequencies of tropical storms and hurricanes). Additional examples are derived from a coastal monitoring site (LEO) on the Atlantic coast of New Jersey and Galveston Bay, on the Gulf of Mexico. In order to assess structure, function, and trophic state of these and other coastal ecosystems, molecular (DNA and RNA-based) characterizations of the microbial taxa involved in carbon, nitrogen and other nutrient transformations can be combined with diagnostic pigment-based indicators of primary producer groups. Application of these methods can reveal process-level microbial community responses to environmental variability over a range of scales. Experimental approaches combined with strategic monitoring utilizing these methods will facilitate: (a) understanding organismal and community responses to environmental change, and (b) synthesizing these responses in the context of ecosystem models that integrate physical, chemical and biotic variability with environmental controls. This revised version was published online in August 2006 with corrections to the Cover Date.     

Chymotrypsin inhibitor from potatoes: interaction with target enzymes

The interactions of chymotrypsin, subtilisin and trypsin with a low MW proteinase inhibitor from potatoes were investigated. The K_i value calculated for the binding of inhibitor to chymotrypsin was 1.6 ± 0.9 × 10^?10M, while the second-order rate constant for association was 6 × 10⁵ M^?1/sec. Although binding was not observed to chymotrypsin which had been treated with diisopropyl fluorophosphate or with l-tosylamide-2-phenylethyl chloromethyl ketone, the 3-methylhistidine-57 derivative bound inhibitor with a K_i value of 9.6 × 10^?9 M. The inhibitor also exhibited a tight association with subtilisin (K_i < 4 × 10^?9 M). In contrast, little inhibition of trypsin was observed, and this was believed to be due to low levels of a contaminant in our preparations. No evidence for reactive site cleavage was observed after incubation of the inhibitor with catalytic amounts of chymotrypsin or subtilisin at acid pH.     

Relationship between leptin receptor and polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders, which is involved in the multi-system disease, and its etiology is still not clearly understood. It is currently considered that not only the genetic factors but also the environment factors play a crucial role in the pathogenesis of PCOS. Obesity plays an important role through the insulin, leptin and endocannabinoid system in the pathological process of PCOS, leading to more severe clinical manifestations. The aim of our present study is to investigate whether there is association between single nucleotide polymorphisms (SNPs) of Gln223Arg and Pro1019Pro in the leptin receptor gene (LEPR) and PCOS in a Korean population. Interestingly, a significant association was found between the Pro1019Pro in LEPR gene and PCOS, and a highly significant association was found between the Gln223Arg in LEPR gene and PCOS (P = 0.033, OR = 1.523, 95% confidence interval and P < 0.0001, OR = 0.446, 95% confidence interval). Moreover, genotype combination and haplotype analyses indicate that Gln223Arg and Pro1019Pro polymorphisms of LEPR are significantly associated with the risk of PCOS.