Modeling the structure of the type I peritrophic matrix: characterization of a Mamestra configurata intestinal mucin and a novel peritrophin containing 19 chitin binding domains

Twelve to fourteen integral proteins were found to reside in the Type I peritrophic matrix (PM) of Mamestra configurata (bertha armyworm) larvae. Several methods were employed, including de novo peptide sequencing, the generation of a midgut-specific EST database and immunological screening, which led to the isolation of cDNAs encoding two integral PM proteins. McPM1, the largest PM protein described to date at 202 kDa, was comprised of a concatamer of 19 chitin binding domains (CBD), 12 of which resided within a central repetitive region consisting of six iterations of a two CBD module. The protein was found to reside within the PM primarily as several lower molecular weight, presumably proteolytically processed, forms. McMUC1 was similar in structure to other insect intestinal mucins (IIM) and was highly glycosylated. The expression of both proteins was restricted to the larval midgut. Lower molecular weight proteins that may represent non- and partially glycosylated forms of McMUC1 were also recognized by an anti-McMUC1 antiserum. These were preferentially degraded upon ingestion of M. configurata multi-capsid nucleopolyhedrovirus by larvae, possibly by a viral-encoded metalloprotease. A molecular model of PM structure is presented featuring the interaction of McPM1 with chitin inter-fibril junctions and McMUC1 with the extended chains in the internodal regions. The potential for interaction between PM proteins via intermolecular disulfide bond formation and through association of CBD with N-linked glycans is discussed.     

Effects of rhizobacteria and root symbionts on the reproduction of Meloidogyne javanica and growth of chickpea

The effects of rhizobacteria, i.e. Pseudomonas fluorescens, Azotobacter chyroococcum and Azospirillum brasilense, alone and in combination with root symbionts, Rhizobium sp. and Glomus mosseae, on the growth of chickpea, Cicer arietinum, and reproduction of Meloidogyne jaranica were studied. When added alone G. mosseae was better at improving plant growth and reducing galling and nematode reproduction than any other tested organism. Application of P. fluorescens caused an almost similar increase in plant growth to that caused by Rhizobium sp., while use of A. chroococcum was better than A. brasilense in improving growth of nematode --infected plants. Combined use of P. fluorescens with G. mosseae was better at improving plant growth and reducing galling and nematode multiplication than any other combined treatment.     

Selective distribution of oxysterols in atherosclerotic lesions and human plasma lipoproteins

The presence of oxidized sterols (oxysterols) in human serum and lesions has been linked to the initiation and progression of atherosclerosis. Data concerning the origin, identity and quantity of oxysterols in biological samples are controversial and inconsistent. This inconsistency may arise from different analytical methods or handling conditions used by different investigators. In the present study, oxysterol levels and distribution were analyzed by an optimized GC-MS method, in human atherosclerotic coronary and carotid lesions, in atherosclerotic apolipoprotein E deficient mice (E degrees mice) and in native and in vitro oxidized human low and high density lipoproteins. Oxysterol levels were analyzed with a limit of detection of 0.06 - 0.24 ng, with 25-hydroxycholesterol (25-OH) being the least sensitive. In human coronary and carotid lesions, obtained from endatherectomic samples, 27-hydroxycholesterol (27-OH) was the major oxysterol, with about 85% as sterols esterified to fatty acids. While total cholesterol and oxysterols levels were similar in both kinds of human lesions, oxysterol distribution was significantly different. In coronary lesions the mean levels of 27-OH and 7beta-hydroxycholesterol (7beta-OH) were 38% and 20% of total oxysterols, whereas in carotid lesions their mean levels were 66% and 5%, respectively. Unlike in human aortic lesions, 27-OH was entirely absent in E degrees mice, whereas the level of 7alpha-hydroxycholesterol (7alpha-OH) was 28% of the total oxysterols, vs. 5% in human coronary lesions. As 27-OH is an enzymatic product of cholesterol oxidation, this finding may indicate that such an enzymatic process does not take place in E degrees mice.     

Effects of endosulfan on intestinal functions in protein-malnourished rats

In rats fed 18% protein diet, administration of endosulfan (2mg/kg body weight daily for 7 days) significantly decreased the brush border sialic acid and increased the hexoses contents. The intestinal uptake of glucose was increased while that of glycine and calcium was reduced. Brush border enzymes and lipids were not affected. However, in protein malnourished rats (fed 8% protein) exposed to endosulfan, brush border sucrase and peptidase activities were enhanced, while alkaline phosphatase activity was decreased compared to untreated malnourished animals. Membrane sialic acid content was low while fucose and cholesterol levels were augmented in endosulfan fed malnourished animals. The uptake of glucose and glycine was elevated under these conditions. These results Suggest that the nutritional status of the animals has an important bearing on thc susceptibility of intestinal tissue to endosulfan toxicity in rats.     

Characteristics and physiological role of surfactant-like particles secreted by entrocytes

Intestinal epithelium secretes novel unilamellar membranes having characteristics similar to lung surfactants and thus has been named Surfactant-like particles (SLP). The chemical analysis of the membranes revealed cholesterol/phospholipid molar ratio of 0.68-0.78, which is much distinct from that of the underlying microvillus membranes (1.34-1.49). The membrane contains 4-6 proteins with a molar weight of 30-120 kDa and is enriched with alkaline phosphatase, contains low amounts of disaccharidases but no Na+, K(+)-ATPase activity. The secretion of SLP is stimulated by fat feeding. Chronic ethanol ingestion also induces the formation of SLP in rat intestine. A number of physiological functions have been attributed to SLP, which include: (i) as a protective lubricant in intestinal lumen, (ii) a role in triacylglycerol transport, (iii) as a vehicle for the transport of luminal proteins into blood, (iv) as a stratum for the adhesion of microorganisms in intestinal lumen, and (v) a role in trans-signalling mechanism across the basolateral surface of enterocytes.     

Taurine in submandibular gland of the rat: effect of muscarinic drugs.

Taurine exerts a number of actions in mammalian cells, including regulation of ion transport and osmoregulation. The production and secretion of saliva involve transepithelial ion transport, thereby making the plasma-like primary saliva hypotonic before secretion. Therefore, it is plausible to suggest modulation of salivary taurine by muscarinic agents that affect salivary gland function. One of the objectives of this study was to determine tissue content and localization of taurine in the submandibular gland of the rat. Further, we determined whether treatment with muscarinic drugs that either increase (e.g., pilocarpine) or decrease (e.g., propantheline) saliva secretion affects the submandibular gland taurine content. The results indicate that the submandibular gland contains an appreciable amount of taurine (8.9 +/- 0.3 micromoles/g wet wt). Further, acute treatment of the rats with either of the muscarinic drugs did not significantly affect tissue taurine content compared to the control group. By contrast, chronic treatment with propantheline, but not pilocarpine, reduced the tissue content of taurine compared to the control rats (p<0.05). Utilizing light microscopic immunohistochemical techniques, intense immunoreactivity was found primarily in the striated ducts of the submandibular gland. Neither pilocarpine nor propantheline treatment led to differential distribution of immunoreactivity in this tissue. In conclusion, the submandibular gland contains an appreciable amount of taurine, primarily in the striated ducts, that can be decreased by chronic muscarinic receptor blockade.     

An accurate comparative theoretical study of the interaction of furan,pyrrole, and thiophene with various gaseous analytes

An accurate comparison of the interaction of furan, pyrrole, and thiophene with different gaseous analytes is vital not only for understanding the sensing mechanism of corresponding polymers but also for rational design of new materials. In the present study, DFT calculations at (M05-2X/Aug-cc-PVDZ) have been performed to investigate the interaction behavior of furan, pyrrole, and thiophene (as models for their corresponding polymers) with different analytes (NH₃, CO₂, CO, N₂H₄, HCN, H₂O₂, H₂S, CH₄, CH₃OH, SO₂, SO₃, H₂O). The interaction of heterocycles with analytes is illustrated by changes in geometric, energetic, and electronic properties. SAPT calculations were performed for energy decomposition analysis to study the contribution of non-covalent components of the total interaction energy for each complex. Analysis of energetic and electronic properties reveals that all heterocycles are highly sensitive to SO₃. The results suggest that sensing ability of polypyrrole is higher than polyfuran and polythiophene for all analytes.

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Graphical abstract SAPT0 energies (kcal mol^-1) of furan, pyrrole, and thiophene with various gaseous analytes?

     

A novel homozygous frameshift variant in the <Emphasis Type="Italic">MCPH1 gene causes</Emphasis> primary microcephaly in a consanguineous Saudi family

Primary microcephaly (MCPH) is a rare developmental defect characterized by impaired cognitive functions, retarded neurodevelopment and reduced brain size. It is genetically heterogeneous and so far more than 17 genes associated with this disease have been identified. Primary microcephaly type 1 (MCPH1) gene encodes a protein called microcephalin, which is implicated in chromosome condensation and DNA damage induced cellular responses. It is suggested to play a role in neurogenesis and regulation of the size of the cerebral cortex. Whole exome sequencing revealed a novel, homozygous frameshift mutation (c.373_374delAA) in MCPH1 gene in exon 5 resulting in frameshift change from p.Lys125Glusfs*7. Our report presents the results of the simultaneous analysis of the trio exome data of both unaffected parents and their affected son. A homozygous frameshift variant in the MCPH1 gene was identified as a plausible candidate causal variant for the clinical phenotype in this family.     

Simple sequence in brain and nervous system specific proteins.

We examined sequences expressed in the brain and nervous system using EST data. A previous study including sequences thought to have neurological function found a deficiency of simple sequence within such sequences. This was despite many examples of neurodegenerative diseases, such as Huntington disease, which are thought to be caused by expansions of polyglutamine tracts within associated protein sequences. It may be that many of the sequences thought to have neurological function have other additional, non-neurological roles. For this reason, we examined sequences with specific expression in the brain and nervous system, using EST expression data to determine if they too are deficient of simple, repetitive sequences. Indeed, we find this class of sequences to be deficient. Unexpectedly, however, we find sequences expressed in the brain and nervous system to be consistently enriched for histidine-enriched simple sequence. Determining the function of these histidine-rich regions within brain-specific proteins requires more experimental data.