The potential of a jumping spider, Phidippus clarus, as a biocontrol agent

Spiders, particularly assemblages of species, have been shown to be effective in reducing pest insects and crop damage in field crops and orchards. We investigated the potential for a single jumping spider species to reduce pests in a greenhouse setting. We placed three treatments in large enclosures: 1) control treatment of only sweet basil, Ocimum basilicum L.; 2) sweet basil and a phytophagous pest, fourlined plant bug, Poecilocapsus lineatus (F.) (Heteroptera: Miridae); and 3) sweet basil, fourlined plant bug, and jumping spider Phidippus clarus (Keyserling 1884). After 1 wk, jumping spiders reduced the number of plant bugs. Plants exposed to plant bugs alone were significantly shorter than either control plants or plants exposed to plant bugs and spiders. Chlorophyll concentration did not significantly differ across treatments. We discuss the feasibility of using P. clarus and similar salticids in biocontrol.     

Multimodal functional cardiac MRI in creatine kinase-deficient mice reveals subtle abnormalities in myocardial perfusion and mechanics

A decrease in the supply of ATP from the creatine kinase (CK) system is thought to contribute to the evolution of heart failure. However, previous studies on mice with a combined knockout of the mitochondrial and cytosolic CK (CK(-/-)) have not revealed overt left ventricular dysfunction. The aim of this study was to employ novel MRI techniques to measure maximal myocardial velocity (V(max)) and myocardial perfusion and thus determine whether abnormalities in the myocardial phenotype existed in CK(-/-) mice, both at baseline and 4 wk after myocardial infarction (MI). As a result, myocardial hypertrophy was seen in all CK(-/-) mice, but ejection fraction (EF) remained normal. V(max), however, was significantly reduced in the CK(-/-) mice [wild-type, 2.32 +/- 0.09 vs. CK(-/-), 1.43 +/- 0.16 cm/s, P < 0.05; and wild-type MI, 1.53 +/- 0.11 vs. CK(-/-) MI, 1.26 +/- 0.11 cm/s, P = not significant (NS), P < 0.05 vs. baseline]. Myocardial perfusion was also lower in the CK(-/-) mice (wild-type, 6.68 +/- 0.27 vs. CK(-/-), 4.12 +/- 0.63 ml/g.min, P < 0.05; and wild-type MI, 3.97 +/- 0.65 vs. CK(-/-) MI, 3.71 +/- 0.57 ml/g.min, P = NS, P < 0.05 vs. baseline), paralleled by a significantly reduced capillary density (histology). In conclusion, myocardial function in transgenic mice may appear normal when only gross indexes of performance such as EF are assessed. However, the use of a combination of novel MRI techniques to measure myocardial perfusion and mechanics allowed the abnormalities in the CK(-/-) phenotype to be detected. The myocardium in CK-deficient mice is characterized by reduced perfusion and reduced maximal contraction velocity, suggesting that the myocardial hypertrophy seen in these mice cannot fully compensate for the absence of the CK system.     

Sequential N- to C-terminal SNARE complex assembly drives priming and fusion of secretory vesicles

During exocytosis a four-helical coiled coil is formed between the three SNARE proteins syntaxin, synaptobrevin and SNAP-25, bridging vesicle and plasma membrane. We have investigated the assembly pathway of this complex by interfering with the stability of the hydrophobic interaction layers holding the complex together. Mutations in the C-terminal end affected fusion triggering in vivo and led to two-step unfolding of the SNARE complex in vitro, indicating that the C-terminal end can assemble/disassemble independently. Free energy perturbation calculations showed that assembly of the C-terminal end could liberate substantial amounts of energy that may drive fusion. In contrast, similar N-terminal mutations were without effects on exocytosis, and mutations in the middle of the complex selectively interfered with upstream maturation steps (vesicle priming), but not with fusion triggering. We conclude that the SNARE complex forms in the N- to C-terminal direction, and that a partly assembled intermediate corresponds to the primed vesicle state.     

Dissecting docking and tethering of secretory vesicles at the target membrane

Secretory vesicles dock at their target in preparation for fusion. Using single-vesicle total internal reflection fluorescence microscopy in chromaffin cells, we show that most approaching vesicles dock only transiently, but that some are captured by at least two different tethering modes, weak and strong. Both vesicle delivery and tethering depend on Munc18-1, a known docking factor. By decreasing the amount of cortical actin by Latrunculin A application, morphological docking can be restored artificially in docking-deficient munc18-1 null cells, but neither strong tethering nor fusion, demonstrating that morphological docking is not sufficient for secretion. Deletion of the t-SNARE and Munc18-1 binding partner syntaxin, but not the v-SNARE synaptobrevin/VAMP, also reduces strong tethering and fusion. We conclude that docking vesicles either undock immediately or are captured by minimal tethering machinery and converted in a munc18-1/syntaxin-dependent, strongly tethered, fusion-competent state.     

NMR solution structures of LNA (locked nucleic acid) modified quadruplexes

We have determined the NMR solution structures of the quadruplexes formed by d(TGLGLT) and d(TL₄T), where L denotes LNA (locked nucleic acid) modified G-residues. Both structures are tetrameric, parallel and right-handed and the native global fold of the corresponding DNA quadruplex is retained upon introduction of the LNA nucleotides. However, local structural alterations are observed owing to the locked LNA sugars. In particular, a distinct change in the sugar–phosphate backbone is observed at the G2pL3 and L2pL3 base steps and sequence dependent changes in the twist between tetrads are also seen. Both the LNA modified quadruplexes have raised thermostability as compared to the DNA quadruplex. The quadruplex-forming capability of d(TGLGLT) is of particular interest as it expands the design flexibility for stable parallel LNA quadruplexes and shows that LNA nucleotides can be mixed with DNA or other modified nucleic acids. As such, LNA-based quadruplexes can be decorated by a variety of chemical modifications. Such LNA quadruplex scaffolds might find applications in the developing field of nanobiotechnology.     

Multiple features contribute to the use of the immunoglobulin M secretion-specific poly(A) signal but are not required for developmental regulation

The secretory-specific poly(A) signal (mus) of the immunoglobulin mu gene plays a central role in regulating alternative RNA processing to produce RNAs that encode membrane-associated and secreted immunoglobulins. This poly(A) signal is in direct competition with a splice reaction, and regulation requires that these two reaction efficiencies be balanced. The mus poly(A) signal has several unique sequence features that may contribute to its strength and regulation. Site-directed mutations and small internal deletions made in the intact mu gene show that an extensive AU/A-rich sequence surrounding AAUAAA enhances signal use and that, of the two potential downstream GU-rich elements, both of which appear suboptimally located, only the proximal GU-rich sequence contributes substantially to use of this signal. A GU-rich sequence placed at a more standard location did not improve mus poly(A) signal use. All mu genes tested that contained modified mus poly(A) signals were developmentally regulated, indicating that the GU-rich sequences, the sequences between them previously identified as suboptimal U1A binding sites, and an upstream suboptimal U1A site do not contribute to mu mRNA processing regulation. Expression of wild-type and modified mu genes in HeLa cells overexpressing U1A also failed to demonstrate that U1A contributes to mus poly(A) signal regulation.     

Munc18-bound syntaxin readily forms SNARE complexes with synaptobrevin in native plasma membranes

Munc18–1, a protein essential for regulated exocytosis in neurons and neuroendocrine cells, belongs to the family of Sec1/Munc18-like (SM) proteins. In vitro, Munc18–1 forms a tight complex with the SNARE syntaxin 1, in which syntaxin is stabilized in a closed conformation. Since closed syntaxin is unable to interact with its partner SNAREs SNAP-25 and synaptobrevin as required for membrane fusion, it has hitherto not been possible to reconcile binding of Munc18–1 to syntaxin 1 with its biological function. We now show that in intact and exocytosis-competent lawns of plasma membrane, Munc18–1 forms a complex with syntaxin that allows formation of SNARE complexes. Munc18–1 associated with membrane-bound syntaxin 1 can be effectively displaced by adding recombinant synaptobrevin but not syntaxin 1 or SNAP-25. Displacement requires the presence of endogenous SNAP-25 since no displacement is observed when chromaffin cell membranes from SNAP-25–deficient mice are used. We conclude that Munc18–1 allows for the formation of a complex between syntaxin and SNAP-25 that serves as an acceptor for vesicle-bound synaptobrevin and that thus represents an intermediate in the pathway towards exocytosis.     

Body composition and physical performance during a National Collegiate Athletic Association Division I men's soccer season

The purpose of this study was to examine changes in body composition (BC) and physical performance tests (PT) resulting from a competitive season in soccer. Twenty-five male collegiate players (age = 19.9 +/- 1.3 years; height = 177.6 +/- 6.4 cm; body mass = 77.6 +/- 8.6 kg, and percentage body fat = 12.8 +/- 5.2%) were tested before (PRE) and after (POST) the 2003-2004 National Collegiate Athletic Association season. The following tests were performed: BC (anthropometric and dual energy x-ray absorptiometry measurements), vertical jump (VJ), 9.1-m (9 m) and 36.5-m (36 m) sprint, lower-body power (LP), total body power (TP), and cardiorespiratory endurance (VO(2)max). Training was divided into soccer-specific training: field warm-up drills, practices, games, and additional conditioning sessions. A daily, unplanned, nonlinear periodization model was used to assign session volume and intensity for strength sessions (total repetitions < or =96 and workload was > or =80% of 1 repetition maximum). For the entire team, body mass significantly increased by 1.5 +/- 0.4 kg from PRE to POST due to a significant increase in total lean tissue (0.9 +/- 0.2 kg). Regionally, lean tissue mass significantly increased in the legs (0.4 +/- 0.0 kg) and trunk (0.3 +/- 0.1 kg). Physical performance variables were very similar for the entire team at PRE and POST; VJ (cm) = 61.9 +/- 7.1 PRE vs. 63.3 +/- 8.0 POST, 9.1-m (s) = 1.7 +/- 0.1 PRE and POST, 36.5-m (s) = 5.0 +/- 0.2 PRE and POST, predicted VO(2)max (ml.kg.min(-1))= 59.8 +/- 3.3 PRE vs. 60.9 +/- 3.4 POST. The only significant improvements across the season were for TP (17.3%) and for LP (10.7%). In conclusion, soccer athletes who begin a season with a high level of fitness can maintain, and in some cases improve, body composition and physical performance from before to after a competitive season. A correct combination of soccer-specific practices and strength and conditioning programs can maintain and develop physical performance, allowing a soccer athlete to perform optimally throughout pre-, in-, and postseason play.     

XIAP Is a copper binding protein deregulated in Wilson's disease and other copper toxicosis disorders

X-linked inhibitor of apoptosis (XIAP), known primarily for its caspase inhibitory properties, has recently been shown to interact with and regulate the levels of COMMD1, a protein associated with a form of canine copper toxicosis. Here, we describe a role for XIAP in copper metabolism. We find that XIAP levels are greatly reduced by intracellular copper accumulation in Wilson's disease and other copper toxicosis disorders and in cells cultured under high copper conditions. Elevated copper levels result in a profound, reversible conformational change in XIAP due to the direct binding of copper to XIAP, which accelerates its degradation and significantly decreases its ability to inhibit caspase-3. This results in a lowering of the apoptotic threshold, sensitizing the cell to apoptosis. These data provide an unsuspected link between copper homeostasis and the regulation of cell death through XIAP and may contribute to the pathophysiology of copper toxicosis disorders.