Probable mechanism of sexual dimorphism in insulin control of Drosophila heat stress resistance

Adult males of Drosophila species (Drosophila melanogaster L. and Drosophila virilis) show a lower tolerance to heat stress compared with females. The present study investigates the effects of RNA interference (RNAi) knockdown of the insulin‐like receptor in the corpus allatum of D. melanogaster males on dopamine metabolism and content, heat stress resistance and juvenile hormone metabolism. In male flies, the knockdown of insulin‐like receptor in the corpus allatum is shown to change metabolism of juvenile hormone but not dopamine. It is also shown that knockdown of the insulin‐like receptor in the corpus allatum results in a decrease of heat stress resistance in females but not males, and that juvenile hormone rescues this decrease. The results suggest that at least one of the ways in which insulin‐like growth factors affect heat stress resistance is by successive mediation through juvenile hormone and dopamine, which could lead to sexual dimorphism in the trait.     

laminin alpha 1 gene is essential for normal lens development in zebrafish

Background  

Laminins represent major components of basement membranes and play various roles in embryonic and adult tissues. The functional laminin molecule consists of three chains, alpha, beta and gamma, encoded by separate genes. There are twelve different laminin genes identified in mammals to date that are highly homologous in their sequence but different in their tissue distribution. The laminin alpha -1 gene was shown to have the most restricted expression pattern with strong expression in ocular structures, particularly in the developing and mature lens.     

Lake Ladoga: chemical pollution and biochemical self-purification

In order to evaluate the current state of Lake Ladoga a comprehensive investigation of its pollution by metals, oil products, phenols, anionic detergents and 3,4-benzopyrene was carried out in July 1993. The results indicate a considerable pollution of the lake waters by metals and phenols. High degree of pollution of sediments by oil products and 3,4-benzopyrene was detected in the northern archipelago and bays (Impilahti, Hiidenselka, Pitkäranta) and in the area of Priozersk. A new index (I _t ) is suggested for the estimation of biochemical self-purification capacity of freshwaters. Values of the index obtained for different parts of Lake Ladoga led us to the conclusion that at the present time the lake's capability for biochemical self-purification is relatively low. This situation is caused by strong anthropogenic impact on the lake. The approximate pollutant loads to Lake Ladoga were estimated on the basis of our 1991–1993 monitoring survey and from literature data.     

A de novo designed 11 kDa polypeptide: Model for amyloidogenic intrinsically disordered proteins

A de novo polypeptide GH₆[(GA)₃GY(GA)₃GE]₈GAH₆ (YE8) has a significant number of identical weakly interacting β‐strands with the turns and termini functionalized by charged amino acids to control polypeptide folding and aggregation. YE8 exists in a soluble, disordered form at neutral pH but is responsive to changes in pH and ionic strength. The evolution of YE8 secondary structure has been successfully quantified during all stages of polypeptide fibrillation by deep UV resonance Raman (DUVRR) spectroscopy combined with other morphological, structural, spectral, and tinctorial characterization. The YE8 folding kinetics at pH 3.5 are strongly dependent on polypeptide concentration with a lag phase that can be eliminated by seeding with a solution of folded fibrillar YE8. The lag phase of polypeptide folding is concentration dependent leading to the conclusion that β‐sheet folding of the 11‐kDa amyloidogenic polypeptide is completely aggregation driven. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 607–618, 2010. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com     

Row-like organization of ATP synthase in intact mitochondria determined by cryo-electron tomography

The fine structure of intact, close-to-spherical mitochondria from the alga Polytomella was visualized by dual-axis cryo-electron tomography. The supramolecular organization of dimeric ATP synthase in the cristae membranes was investigated by averaging subvolumes of tomograms and 3D details at ∼ 6 nm resolution were revealed. Oligomeric ATP synthase is composed of rows of dimers at 12 nm intervals; the dimers make a slight angle along the row. In addition, the main features of monomeric ATP synthase, such as the conically shaped F₁ headpiece, central stalk and stator were revealed. This demonstrates the capability of dual-axis electron tomography to unravel details of proteins and their interactions in complete organelles.     

Ecdysteroids: isolation,chemical transformations,and biological activity

Phytochemistry Reviews - Ecdysteroids are polyhydroxylated sterols, and are widespread in the plant and animal world. To date, over 520 ecdysteroids have been isolated from natural sources. The...