Size at first sexual maturity of two species of rajoid skates, genera Atlantoraja and Dipturus (Pisces, Elasmobranchii, Rajidae), from the south-western Atlantic Ocean

Total length (TL) at first sexual maturity was estimated for Atlantoraja castelnaui and Dipturus chilensis from the south‐western Atlantic Ocean. Total length at which 50% of the females were captured (50% c) was less than the TL at first sexual maturity (ML) in both species. Immature females are being captured and thus will not become sexually mature to reproduce because of early fishing mortality. Females of A. castelnaui and D. chilensis reach sexual maturity at TLs of 110–114 cm and 102–106 cm, respectively. Males mature with TL between 91 and 95 cm for A. castelnaui and between 83 and 87 cm for D. chilensis.     

Distribuzione del fitoplancton in un'area salmastra della Sicilia nord-orientale

Abstract

Phytoplankton distribution in a brackish area of North-Eastern Sicily -The abundance and taxonomic composition of the phytoplankton have been studied in relation to temperature, salinity and dissolved oxygen in the brackish pools of Oliveri-Tindari, a very restricted area on the Tyrrhenian coast of Sicily (Italy). The phytoplankton distribution in these pools has been subject to relatively few investigations. Although this area is not influenced by sewage and industrial effluents, some pools showed episodical high densities of phytoplankton, due to the influence of organic inputs (streams and water-bearings), and anoxic conditions.

The microalgal communities were generally characterized by chlorophyceans, although sometimes other taxa prevailed.     

Binding of native and [homoserine lactone-52]-52,53-seco-bovine basic pancreatic trypsin inhibitor (kunitz inhibitor) to porcine pancreatic β-kallikrein-B and bovine α-chymtorpsin: Thermodynaic study

Values of the association equilibrium constant (K_a) for the binding of the native and of the cyanogen bromide-cleaved bovine basic pancreatic trypsin inhibitor (native BPTI and [Hse lactone-52]-52,53-seco-BPTI, respectively) to neuraminidase-treated porcine pancreatic β-Kallikrein-B (kallikrein) and bovine α-chymotrypsin (chymotrypsin) have been determined between pH4.0 and 9.0, and 20.0°C. Over the whole pH range explored, native BPTI and [Hse lactone-52]-52,53-seco-BPTI show the same affinity for kallikrein. On the other hand, the affinity of [se lactone-52]-52,53-seco-BPTI for chymotrypsin is high4er, around neutrality, than that found for native BPTI by about one order of magnitude, coverging in the acidic pH limb. The simplest mechanism accounting for the observed data implies that, on lowering the pH from 9.0 to 4.0 (i) the decrease in affinity for the binding of native BPTI to kalikrein and chymotrypsin, as well as for the association of [Hse lactone-52]-52,53-seco-BPTI to kalikrein, reflects the acidic pK shift, upon inhibitor association, of a single inozing group; and (ii) the decrease of K_a values for [Hse lactone-52]-52,53-seco-BPTI binding to chymotrypsin appears to be modulated by the acidic pK shift, upon inhibitor association, of two non-equivalent proton-binding residues. On the basis of the stereochemistry of the serine proteinase/inhibitor contact region(s), these data indicate that long-rang structural changes in [Hse lactone-52]-52,53-seco-BPTI are energetically linked to the chymotrypsin: inhibitor complex formation. This observation represents an important aspect for the mechanism of molecular recognition and regulation in BPTI.     

Egg capsules of the dusky catshark Bythaelurus canescens (Carcharhiniformes,Scyliorhinidae) from the south‐eastern Pacific Ocean

The external morphology of the egg capsule of Bythaelurus canescens and its fixation to the substratum are described. Bythaelurus canescens egg capsules are typically vase‐shaped, dorso‐ventrally flattened, pale yellow in colour when fresh and covered by 12–15 longitudinal ridges. The anterior border of the capsule is straight, whereas the posterior border is semicircular. Two horns bearing long, coiled tendrils arise from the anterior and posterior ends of the capsule. The presence of longitudinal ridges and long coiled tendrils at both anterior and posterior ends of the capsule readily distinguish these egg capsules from those of other chondrichthyans occurring in the south‐east Pacific Ocean.     

Dual inducible expression of recombinant GFP and targeted antisense RNA in Lactococcus lactis

The food-grade status and probiotic activity of lactic acid bacteria (LAB) make them attractive hosts for production and oral delivery of therapeutic heterologous vaccines and other proteins, yet these bacteria currently do not achieve recombinant protein expression at levels comparable to those seen in Escherichia coli and Saccharomyces cerevisiae. Limited levels of expressed recombinant protein per cell most likely constrain the vaccine’s immunogenic potential with respect to the magnitude and specificity of the immune response. With the goal of increasing recombinant protein expression per cell in Lactococcus lactis IL1403, a model LAB, we have constructed and evaluated a new vector that permits simultaneously-induced expression of GFP, a model recombinant protein, and antisense RNA inhibition of the clpP-encoded intracellular protease. While silencing of the rational target clpP does not lead to increased GFP per cell, the new dual-expression system provides an efficient and potentially high-throughput metabolic engineering tool for strain improvement.