Trichoderma reesei sequences that bind to the nuclear matrix enhance transformation frequency

Three DNA fragments, trs1, 2 and 3, were isolated from the Trichoderma reesei genome on the basis of their ability to promote autonomous replication of plasmids in Saccharomyces cerevisiae. Each trs element bound specifically to the isolated T. reesei nuclear matrix in vitro, and two of them bound in vivo, indicating that they are matrix attachment regions (MARs). A similar sequence previously isolated from Aspergillus nidulans (ans1) was also shown to bind specifically to the T. reesei nuclear matrix in vitro. The T. reesei MARs are AT-rich sequences containing 70%, 86% and 73% A+T over 2.9, 0.8 and 3.7 kb, respectively for trs1, 2 and 3. They exhibited no significant sequence homology, but were shown to contain a number of sequence motifs that occur frequently in many MARs identified in other eukaryotes. However, these motifs occurred as frequently in the trs elements as in randomly generated sequences with the same A+T content. trs1 and 3 were shown to be present as single copies in the T. reesei genome. The presence of the trs elements in transforming plasmids enhanced the frequency of integrative transformation of T. reesei up to five fold over plasmids without a trs. No evidence was obtained to suggest that the trs elements promoted efficient replication of plasmids in T. reseei. A mechanism for the enhancement of transformation frequency by the trs elements is proposed. Received: 1 March 1997 / Accepted: 13 May 1997     

High performance liquid chromatography,chemical laboratory practice: By Heinz Engelhardt. Springer-Verlag,New York/Berlin, 1979. 248 pp. $29.80

A gel filtration method has been developed for the complete removal of sodium dodecyl sulfate (SDS) from proteins and peptides. The protein or peptide (20 μg–10 mg) containing SDS (up to 30–60 mg) is dissolved in a mixture of propionic acid, formic acid, and water (2:1:2, $\text{v}\text{v}$). Under these conditions, protein-SDS (or peptide-SDS) complexes, as well as SDS micelles, are dissociated. Subsequently, protein and SDS can be separated on a small Sephadex G-25 superfine column. The recovery of protein is typically 90% or more.     

Improved assay of coenzyme F420 analogues from methanogenic bacteria

Summary An improved method for separating analogues of coenzyme F₄₂₀ by isocratic reversed-phase high performance liquid chromatography is described. The method offers improved resolution, shorter chromatography runs and requires less complex apparatus.     

Euclein: A new binaphthaquinone from Euclea pseudebenus

7-MethyljugIone, 8,8′-dihydroxy-4,4′-dimethoxy-6,6′-dimethyl-2,2′-binaphthyl-1,1′-quinone, 2-methylnaphthazarin, mamegakinone and euclein have been isolated from Euclea pseudebenus. Euclein is the 3,6′-dimer of 7-methyljuglone.     

Twilight activity patterns and angling vulnerability of yellowmouth barracuda (Sphyraena viridensis Cuvier, 1829), a range-expanding thermophilic fish

Among the thermophilic fishes that have become established in the north-western Mediterranean as a consequence of sea warming, the yellowmouth barracuda (Sphyraena viridensis Cuvier, 1829) appears to be one of the most successful and abundant in the coastal rocky environment, having increasingly become the object of recreational and commercial exploitation in the study area. Lure-fishing sessions were carried out from May 2016 to November 2018 in the Catalan Sea (NE Spain) at dawn and dusk, with the aim of providing new insight into the behavioural, spatial and feeding ecology and vulnerability to angling of this poorly known species. Generalized mixed-effects linear models showed that S. viridensis is a crepuscular inshore dweller, whose vulnerability to angling is significantly influenced by solar and lunar light intensities, being highest in the pre-spawn and spawning periods. Asymmetries between dawn and dusk activity patterns were detected, evidently related to a drop in aggressiveness at dusk following the spawning period. The simple study design adopted may be applied to other contexts, aiming to the recognition of several levels of fish vulnerability to angling.     

Accelerated disulfide reduction with polyunsaturated fatty acids: a mechanism of ionic channel modulation?

Summary

Polyunsaturated fatty acids (PUFAs) have been shown to modulate the activity of ionic channels by an unknown mechanism. Some channels are activated (i.e. certain delayed-rectifier, potassium channels) and others are inhibited (i.e. certain calcium, sodium and other potassium channels). We have previously demonstrated that PUFAs can act as electron carriers. It is known that ionic channels can be redox modulated. The ability of fatty acids to serve as electron shuttling agents is proportional to their unsaturation. These PUFAs cause reduction of disulfides through a superoxide radical-independent mechanism, probably related to enhanced electron delocalization. The present study shows that there is a strong correlation between the ability of a PUFA to transfer an electron to a disulfide and its reported ability to modulate ionic channels. This suggests that electron transfer could be the mechanism of PUFAs action on particular ionic channels.