Untangling spider silk evolution with spidroin terminal domains

Background  

Spidroins are a unique family of large, structural proteins that make up the bulk of spider silk fibers. Due to the highly variable nature of their repetitive sequences, spidroin evolutionary relationships have principally been determined from their non-repetitive carboxy (C)-terminal domains, though they offer limited character data. The few known spidroin amino (N)-terminal domains have been difficult to obtain, but potentially contain critical phylogenetic information for reconstructing the diversification of spider silks. Here we used silk gland expression data (ESTs) from highly divergent species to evaluate the functional significance and phylogenetic utility of spidroin N-terminal domains.     

Cyclic AMP, the hyperresponsiveness factor from hog kidney

The isolation and identification of a material present in the plasma of hypertensive dogs and hypertensive human patients has been under study since 1972. The earliest experiments in relation to this work, noted that plasma from hypertensive dogs cause a hyperresponse to norepinephrine when both were administered by way of the vein. Employing a rat assay system that consisted of an anesthetized rat with polyethylene catheters in the vein for giving norepinephrine and the test fractions and a catheter in the artery for blood pressure monitoring, fractions from hog kidney were tested for hyperresponsiveness activity. The active material is very comparable to cyclic AMP in molecular weight, ultraviolet spectrum, paper chromatography, Enzyme hydrolysis and activity in the anesthetized rat system. This evidence indicates that the hyperresponsiveness factor of renal origin is cyclic AMP.     

Typing of Genetic Markers Involved in Stress Response by Fluorescent cDNA-Amplified Fragment Length Polymorphism Technique

Identification of genetic markers involved in stress response to physical factors or chemical substances in organisms is a challenging task. Typing of upregulated gene expression due to selective antibacterial pressure is a promising approach in the search of molecular mechanisms responsible for development of resistance. cDNA-Fluorescent Amplified Fragment Length Polymorphism (cDNA-FAFLP) strategy was developed and applied in the search of antimycotic drug resistance marker(s) in medically important fungi as an alternative method to microarray analysis. We compared differential gene expression of two sensitive Candida albicans reference strains (ATCC 10231 and ATCC 60133) and two of their paired resistant to fluconazole and itraconazole mutants. Resistant mutants Candida albicans FLC-R, resistant to fluconazole (MIC > 128 μg/ml) and Candida albicans ICZ-R, resistant to itraconazole (MIC > 4 μg/ml) were obtained in subcultures with gradual increase of the antifungal in the culture medium. cDNA-AFLP profile in both itraconazole resistant mutants showed specific spectrophotometric peaks with 5–6-fold RNA overexpression product of 500 bp length compared to the sensitive strains. Fluconazole mutants do not reveal RNA level changes under tested by us typing conditions. These results indicate that the cDNA-FAFLP strategy is a relatively rapid, simple, and reliable method for simultaneous typing of both constitutive and induced differences in expression of host genes providing insight into the biological processes involved in response to drugs in bacteria and fungi. Moreover, this methodology could be tested for typing of the genome response of any organism to physical or chemical stress factors.     

Physical and chemical variability in sugarcane fields infested with the red-striped soft scale insect,Pulvinaria Tenuivalvata (Newstead)

The red-striped soft scale insect Pulvinaria tenuivalvata (Newstead) (Hemiptera: Coccidae) started to infest sugarcane plants (Saccharum officinarum L.) in different districts in Egypt during the last decade. The percentage of infestation was recorded in El-Wakf area, Qena Governorate (Naghhamadi mill zone) Upper Egypt in some fields. There are three levels of infestation, low, intermediate and high. From these fields, samples were selected for physical and chemical studies. The results obtained show that the stalks of infested plants decreased in weight, the sugar content (glucose and sucrose) drastically reduced and as the percentage of infestation increased the percentage of glucose and sucrose content significantly decreased. The primary and secondary humidity and the cellulose content also increased in the healthy plants compared to the infested ones. All the physical character of the infested plants was significantly affected in comparison with the healthy ones.     

Introducing the Multivariate Dale Model in Population‐Based Genetic Association Studies

Until recently, the most common parametric approaches to study the combined effects of several genetic polymorphisms located within a gene or in a small genomic region are, at the genotype level, logistic regressions and at the haplotype level, haplotype analyses. An alternative modeling approach, based on the case/control principle, is to regard exposures (e.g., genetic data such as derived from Single Nucleotide Polymorphisms – SNPs) as random and disease status as fixed and to use a marginal multivariate model that accounts for inter‐relationships between exposures. One such model is the multivariate Dale model. This model is based on multiple logistic regressions. That is why the model, applied in a case/control setting, leads to straightforward interpretations that are similar to those drawn in a classical logistic modeling framework. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Behavioral responses of Diabrotica adults to plant-derived semiochemicals encapsulated in a starch borate matrix

The concept of encapsulating semiochemicals into a starch matrix is being studied for potential use in corn rootworm (CRW) management programs. During 1987, experiments were conducted to determine: 1) If volatile plant-derived Diabrotica spp. attractants could be encapsulated in a starch borate matrix (SBM), and 2) If various SBM-semiochemical formulations would attract Diabrotica species over time in field corn. Chemical analyses of fresh SBM formulations indicated that indole, estragole, veratrole, phenylacetaldehyde, and trans-anethole were not retained during formulation but trans-cinnamaldehyde, Beta-ionone, 1,2,4,-trimethoxybenzene, eugenol and isugenol were successfully encapsulated. Encapsulated semiochemical formulations were made into 20 mesh granules, placed in Pherocon ® 1C traps that were tied to corn plants, and sampled for CRW adults every 4 days from 11 July to 8 September. Field data indicated that encapsulated semiochemicals were retained in the SBM for varying lengths of time and were released at rates attractive to CRW adults. A two-component mixture of trans-cinnamaldehyde and 1,2,4-trimethoxybenzene was the most effective formulation tested; however, no formulation was effective during corn silking and pollination. Although seasonal variation in CRW response could limit the usefulness of some plant-derived semiochemicals, the starch matrix concept may be useful as a delivery system for semiochemicals and may have potential as a tool that could be used in the development of new more biorational CRW management programs.

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Résumé Le programme expérimental de 1987 était destiné à déterminer: 1) si les substances dérivées de végétaux et attractives pour Diabrotica pouvaient être encapsulées dans de l'amidon additionné d'acide borique; 2) si différentes formules attireraient les différentes espèces de Diabrotica dans un champ de maïs.L'indol, l'estragol, le vératrol, le phénylacétaldéhyde et le trans-anéthol n'ont pas été retenus, tandis que le trans-cinnamaldéhyde, la \-ionone, le 1,2,4-triméthobenzène, l'eugénol et l'isugénol ont été encapsulés avec succès dans des pièges attachés à des pieds de maïs (les détails techniques sont fournis). Les pièges ont été relevés tous les 4 jours du 11 juillet au 8 septembre. Les résultats montrent que les substances allélochimiques sont conservées dans la capsule pendant des durées variables et libérées à des concentrations attractives pour les Diabrotica adultes. Un mélange de trans-cinnamaldéhyde et de 1,2,4,-triméthoxybenzène a été la formule la plus efficace, à l'exception des périodes de formation des barbes et du pollen, où aucune formule n'a été attractive. Bien que la variation saisonnière des réactions de Diabrotica limite l'utilisation des substances allélochimiques d'origine végétale, la capsule d'amidon peut être employée pour libérer des substances allélochimiques et constitue un outil potentiel pour la mise au point d'une méthode plus rationnelle de lutte contre Diabrotica.