Levels of gene flow among populations of a wolf spider in a recently fragmented habitat: current versus historical rates

Gene flow among populations is important for countering the deleterious effects of random genetic drift and inbreeding, as well as spreading beneficial mutations. Wind-driven aerial dispersal is known to occur in numerous plants and invertebrates. Its evolution suggests that historically, suitable habitat patches were dense enough to make such undirected dispersal evolutionarily advantageous. Using microsatellite markers we assessed the population genetic structure of seven populations of a wolf spider (Rabidosa rabida) capable of ballooning. Historically, each spider population received a mean of 1.5 migrants per generation from the other six populations. Over the past several generations the number of migrants reaching a population is only 0.2. This statistically significant reduction in gene flow coincides with high levels of habitat fragmentation and suggests that undirected aerial dispersal is ineffective in this fragmented landscape. Further, individuals within populations showed signficantly elevated levels of homozygosity relative to Hardy–Weinberg expectations, suggesting that cursorial dispersal may be very limited and genetic structure within populations exists. Inbreeding coefficients averaged 0.18 over all seven populations with very little variation among populations (s = 0.02). Fitness was lower in smaller populations relative to larger ones. Altered landscapes pose evolutionary dilemmas for many metapopulations and species that depend on undirected movement for dispersal may be particularly vulnerable to habitat fragmentation.     

Adult human brain neural progenitor cells (NPCs) and fibroblast-like cells have similar properties in vitro but only NPCs differentiate into neurons

The ability to culture neural progenitor cells from the adult human brain has provided an exciting opportunity to develop and test potential therapies on adult human brain cells. To achieve a reliable and reproducible adult human neural progenitor cell (AhNPC) culture system for this purpose, this study fully characterized the cellular composition of the AhNPC cultures, as well as the possible changes to this in vitro system over prolonged culture periods. We isolated cells from the neurogenic subventricular zone/hippocampus (SVZ/HP) of the adult human brain and found a heterogeneous culture population comprised of several types of post-mitotic brain cells (neurons, astrocytes, and microglia), and more importantly, two distinct mitotic cell populations; the AhNPCs, and the fibroblast-like cells (FbCs). These two populations can easily be mistaken for a single population of AhNPCs, as they both proliferate under AhNPC culture conditions, form spheres and express neural progenitor cell and early neuronal markers, all of which are characteristics of AhNPCs in vitro. However, despite these similarities under proliferating conditions, under neuronal differentiation conditions, only the AhNPCs differentiated into functional neurons and glia. Furthermore, AhNPCs showed limited proliferative capacity that resulted in their depletion from culture by 5-6 passages, while the FbCs, which appear to be from a neurovascular origin, displayed a greater proliferative capacity and dominated the long-term cultures. This gradual change in cellular composition resulted in a progressive decline in neurogenic potential without the apparent loss of self-renewal in our cultures. These results demonstrate that while AhNPCs and FbCs behave similarly under proliferative conditions, they are two different cell populations. This information is vital for the interpretation and reproducibility of AhNPC experiments and suggests an ideal time frame for conducting AhNPC-based experiments.     

Homology Modeling of Coagulase in Staphylococcus aureus

The close correlation between the ability of coagulase to clot blood plasma and their capacity to produce disease, and the corresponding absence of this property in nonpathogenic strains, have led to the assumption that the coagulase, plays important role in the pathogenesis of disease. Currently, crystal structure of coagulase in Staphylococcus aureus remains indefinable. Thus, the objectives of this research is to generate the three dimensional model of coagulase in S. aureus by using homology modeling approach. In this study, we used bioinformatics tools and databases such as BLAST (Basic Local Alignment Search Tool), GenBank, PDB (Protein Databank), and Discovery Studio to gain specific functional insights into coagulase. The model was validated using protein structure checking tools such as PROCHECK, Verify 3D and CE (Combinatorial Extension) for reliability. Therefore, structure prediction of coagulase in S. aureus can provide preliminary knowledge for understanding the function of the protein. The information from this finding will provide important information into the action and regulation mechanism of the coagulase protein in S. aureus.     

Flow modelling within a scaffold under the influence of uni-axial and bi-axial bioreactor rotation

The problem of donor scarcity has led to the recent development of tissue engineering technologies, which aim to create implantable tissue equivalents for clinical transplantation. These replacement tissues are being realised through the use of biodegradable polymer scaffolds; temporary/permanent substrates, which facilitate cell attachment, proliferation, retention and differentiated tissue function. To optimise gas transfer and nutrient delivery, as well as to mimic the fluid dynamic environment present within the body, a dynamic system might be chosen. Experiments have shown that dynamic systems enhance tissue growth, with the aid of scaffolds, as compared to static culture systems. Very often, tissue growth within scaffolds is only seen to occur at the periphery. The present study utilises the Computational Fluid Dynamics package FLUENT, to provide a better understanding of the flow phenomena in scaffolds, within our novel bioreactor system. The uni-axial and bi-axial rotational schemes are studied and compared, based on a vessel rotating speed of 35 rpm. The wall shear stresses within and without the constructs are also studied. Findings show that bi-axial rotation of the vessel results in manifold increases of fluid velocity within the constructs, relative to uni-axial rotation about the X- and Z-axes, respectively.     

Interactions betweenpanax quinquefoliumsaponis and vitamin C are observed in vitro

Inasmuch as the oxidation of low-density lipoprotein (Ox-LDL) may play a key role in the initiation and progression of atherosclerosis, it has become increasingly important to identify potential antioxidants. Panax quinquefolium saponins (PQS) are extracted from the stems and leaves of the North American form of ginseng,Panax quinquefolium. Our previous studies have indicated that PQS (0.25-1 mg/ml) can protect against oxidation of LDLin vitro. The purpose of the current work was to investigate the potential interaction of lower concentrations of PQS (1-100 g/ml) with vitamin C on the reduction of LDL oxidation. LDL was isolated from the plasma of healthy human donors by sequential ultracentrifugation. Native LDL (0.05 or 0.2 mg/ml) was incubated with PQS and/or vitamin C for 30 min at 20°C. Oxidative modification was initiated with 2 M or 5 M CuSO₄ at 37°C for 0-24 h. Pretreatment with PQS (100 g/ml) reduced alterations in phospholipids, lipid peroxide levels and relative electrophoretic mobility of Ox-LDL. The presence of vitamin C (1-10 M) significantly enhanced the protective effects of PQS. Pretreatment with PQS (1-100 g/ml) resulted in concentration-dependent inhibition of LDL oxidation and prolongation of lag time as determined from measurements of conjugated lipid hydroperoxide content in Ox-LDL samples. Interestingly, the inhibitory actions of lower amounts of PQS (1 and 10 g/ml) on the formation of conjugated dienes were significantly increased when vitamin C (0.1 or 1 M) was present. In conclusion, our results suggest that PQS not only have direct antioxidant property but at low concentrations, their actions can be enhanced by vitamin C.     

Heterodigital arterialized flaps for large finger wounds: results and indications

Deep defects of the hand and fingers with an unhealthy bed exposing denuded tendon, bone, joint, or neurovascular structures require flap coverage. However, the location and size of the defects often preclude the use of local flap coverage. Free-flap coverage is often not desirable either, because the recipient vessels may be unhealthy from surrounding infection or trauma. In such situations, a regional pedicled flap is preferable. A solution to this is the heterodigital arterialized flap. This flap is supplied by the digital artery and a dorsal vein of the finger for venous drainage. Unlike the neurovascular island flap, the digital nerve is left in situ in the donor finger, thus avoiding many of the neurologic complications associated with the Littler flap. The digital artery island flap is centered on the midlateral line of the donor finger. It extends from the middorsal line to the midpalmar line. The maximal length of the flap is from the base of the finger to the distal interphalangeal joint. By preserving the pulp and the digital nerve, a sensate pulp on the donor finger remains that reduces donor-finger morbidity and also preserves fingertip cosmesis. Twenty-nine flaps were performed in 29 patients and the outcomes in the donor finger and the reconstructed finger were reviewed. The flap survival was 100 percent. There were no cases of flap ischemia or flap congestion. Good venous drainage of the flap through the additional dorsal vein was helpful in preventing the occurrence of early postoperative venous congestion, which is common in island flaps of the fingers, which depend on only the venae comitantes for drainage. Donor-finger morbidity, measured in terms of range of motion and two-point discrimination in the pulp, was minimal. Ninety-seven percent of the donor fingers achieved excellent or good total active motion according to the criteria of Strickland and Glogovac. Pulp sensation in the donor fingers was normal in 28 of the 29 donor fingers. No cold intolerance of the donor finger or the adjacent finger is reported in this series.     

L-Arabinose induces synthesis of secreted beta-galactosidase in the filamentous fungus penicillium canescens

The mechanism of induction of secreted beta-galactosidase was studied in the filamentous fungus Penicillium canescens. L-Arabinose and its metabolite L-arabitol induce the synthesis of the enzyme. Apart from beta-galactosidase, L-arabinose induces the synthesis of other extracellular carbohydrolases including alpha-L-arabinofuranosidase. Increasing L-arabinose concentration above 1 mM or addition of other carbon sources results in carbon catabolite repression of the synthesis of the secreted enzymes. The data suggest that arabinofuranosidase can regulate the synthesis of secreted enzymes in P. canescens, thus controlling the level of free L-arabinose.     

Length–weight relationships of seven fish species from a fish landing port at Sungai Udang,Penang, Malaysia

The length–weight relationships (LWRs) are described for seven fish species from four families (Ariidae, Clupeidae, Leiognathidae and Sciaenidae) inhabiting Penang waters. A total of 471 specimens were sampled and measured from 19 to 20 January 2015, using a bottom trawl net with a 38 mm mesh size of cod‐end. No information regarding LWRs was reported previously in FishBase for Cryptarius truncatus, Escualosa thoracata, Johnius carouna, Nuchequula blochii, Plicofollis argyropleuron, Secutor hanedai or Secutor megalolepis, and the study also provides a new FishBase record of maximum total length for Escualosa thoracata (10.6 cm), Secutor hanedai (9.1 cm) and Secutor megalolepis (7.5 cm).