Phylogenetics and predictive distribution modeling provide insights into the geographic divergence of Eriosyce subgen. Neoporteria (Cactaceae)

The classification of Eriosyce subgenus Neoporteria (??subsection?? in the sense of Kattermann) and the role of allopatry/sympatry in the diversification of the group were studied by use of cladistic and predictive distribution modeling methods. We reconstructed the phylogenetic relationships of subgenus Neoporteria by analyzing 38 morphological characters and DNA sequences from two chloroplast regions of 21 taxa from the Chilean subsections of Eriosyce using a Bayesian and maximum likelihood phylogenetic framework. Also, we attempted to find out if the divergence between the sister taxa in the Neoporteria group had been caused by allopatric or sympatric mechanisms. The morphology-based analysis placed E. chilensis basal within the Neoporteria clade and suggested a further broadening of the group by including E. taltalensis var. taltalensis, formerly considered a member of subsection Horridocactus. However, the combined DNA data placed E. sociabilis and E. taltalensis var. taltalensis within the Horridocactus clade, and placed E. chilensis with E. subgibbosa var. litoralis. The broad concept of E. subgibbosa sensu Kattermann (comprising seven infraspecific taxa), was rejected by our combined molecular results. Finally, our results corroborated changes in subsection Neoporteria proposed by various authors and suggested further modifications within Neoporteria. The analyses of the degree of geographic overlap of the predicted distributions indicated null overlap between the sister taxa, and one probable hybrid origin of E. chilensis, indicating that evolutionary divergence is mainly caused by an allopatric process associated with climatic tolerance.     

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.     

Multiple conformations of deoxyribonuclease A. Their separation at alkaline pH and low ionic strength in the presence of Ca2+.

Gel filtration on Sephadex G-100 at pH 9.0 in 1 mM Tris buffer produces denaturation and inactivation of pancreatic DNAase A. Limiting concentrations of Ca2+ in the suspension and elution buffer, reactivates some of the enzyme molecules in an amount proportional to the calcium added. Stable active and inactive forms were separated on Sephadex columns. A model for the conformational role of Ca2+ on DNAase A demonstrates that at least one Ca2+ is involved (Kapp = 8.3 . 10(-5) M) in the correct folding of the polypeptide chain. Na+ was unable to reactivate the enzyme.     

Triangle Consortium for Reproductive Biology 22nd Annual Meeting

Mol. Reprod. Dev. 80: 504–507, 2013. © 2013 Wiley Periodicals, Inc. This article is a US government work and, as such, is in the public domain in the United States of America.     

Study of permeation and blocker binding in TMEM16A calcium-activated chloride channels

We studied the effects of mutations of positively charged amino acid residues in the pore of X. tropicalis TMEM16A calcium-activated chloride channels: K613E, K628E, K630E; R646E and R761E. The activation and deactivation kinetics were not affected, and only K613E showed a lower current density. K628E and R761E affect anion selectivity without affecting Na⁺ permeation, whereas K613E, R646E and the double mutant K613E + R646E affect anion selectivity and permeability to Na⁺. Furthermore, altered blockade by the chloride channel blockers anthracene-9-carboxylic acid (A-9-C), 4, 4''-Diisothiocyano-2,2''-stilbenedisulfonic acid (DIDS) and T16inh-A01 was observed. These results suggest the existence of 2 binding sites for anions within the pore at electrical distances of 0.3 and 0.5. These sites are also relevant for anion permeation and blockade.     

In silico prospection of microorganisms to produce polyhydroxyalkanoate from whey: Caulobacter segnis DSM 29236 as a suitable industrial strain

Polyhydroxyalkanoates (PHAs) are polyesters of microbial origin that can be synthesized by prokaryotes from noble sugars or lipids and from complex renewable substrates. They are an attractive alternative to conventional plastics because they are biodegradable and can be produced from renewable resources, such as the surplus of whey from dairy companies. After an in silico screening to search for ß-galactosidase and PHA polymerase genes, several bacteria were identified as potential PHA producers from whey based on their ability to hydrolyse lactose. Among them, Caulobacter segnis DSM 29236 was selected as a suitable strain to develop a process for whey surplus valorization. This microorganism accumulated 31.5% of cell dry weight (CDW) of poly(3-hydroxybutyrate) (PHB) with a titre of 1.5 g l⁻¹ in batch assays. Moreover, the strain accumulated 37% of CDW of PHB and 9.3 g l⁻¹ in fed-batch mode of operation. This study reveals this species as a PHA producer and experimentally validates the in silico bioprospecting strategy for selecting microorganisms for waste re-valorization.     

Nonspecific proteases: a new approach to the isolation of adult cardiocytes

The potent collagenolytic activity of nonspecific proteinases suggested their use as enzymatic agents for the dissociation of single adult heart cells. This was assessed in guinea pig hearts perfused for 1 min with solutions containing hyaluronidase (100-10 000 U/mL), trypsin (100-10 000 U/mL), crude collagenase (100-500 U/mL), or nonspecific protease (0.1-100 U/mL). No rod-shaped cells were observed among the cells isolated with these concentrations of hyaluronidase, trypsin, or crude collagenase. By contrast, 45-80% of the cells released with nonspecific protease (5-10 U/mL) were rod shaped and Ca2+ tolerant. Resting and action potentials recorded from cells dispersed with nonspecific protease were similar to those recorded from cells isolated after prolonged collagenase exposure.     

Rate-dependent action potential changes in rat atrium

Experiments in isolated left atria from rat hearts were performed in order to study the effects of stimulation rate on the transmembrane action potential. 1. Two components (fast and slow) of the action potential upstroke could be differentiated by adding MnCl2 to the perfusion solution. 2. With the increase in rate of stimulation over the control cycle length (500 msec), amplitude, Vmax and action potential duration at 80% of repolarization (D80) diminished in normal Krebs. In Mn-containing Krebs, only a slight reduction in amplitude was recorded. Resting potential and action potential duration at 20% (D20) and 50% (D50) of repolarization were only slightly affected in normal Krebs and not at all in Mn-Krebs. 3. Low rates of stimulation in normal Krebs increased D50 only slightly; however, D80 increased significantly while other parameters remained constant. No effects were seen in Mn-Krebs. 4. The results with Mn-Krebs indicate the importance of slow inward current on changes induced by stimulation rates. A possible mechanism relating intracellular calcium concentration and the outward K current, depending on the rate of stimulation, is discussed.