Peculiarities of Activation of Muscles of the Shoulder Belt in Voluntary Two-Joint Movements of the Upper Limb

We studied coordination of central motor commands (СMCs) coming to muscles of the shoulder and shoulder belt in the course of single-joint and two-joint movements including flexion and extension of the elbow and shoulder joints. Characteristics of rectified and averaged EMGs recorded from a few muscles of the upper limb were considered correlates of the CMC parameters. Special attention was paid to coordination of CMCs coming to two-joint muscles that are able to function as common flexors (m. biceps brachii, caput breve, BBcb) and common extensors (m. triceps brachii, caput longum, TBcl) of the elbow and shoulder joints. Upper limb movements used in the tests included planar shifts of the arm from one spatial point to another resulting from either simultaneous changes in the angles of the shoulder and elbow joints or isolated sequential (two-stage) changes in these joint angles. As was found, shoulder muscles providing movements of the elbow with changes in the angle of the elbow joint, i.e., BBcb and TBcl, were also intensely involved in the performance of single-joint movements in the shoulder joint. The CMCs coming to two-joint muscles in the course of two-joint movements appeared, in the first approximation, as sums of the commands received by these muscles in the course of corresponding single-joint movements in the elbow and shoulder joints. Therefore, if we interpret the isolated forearm movement performed due to a change in the angle of the elbow joint as the main motor event, while the shoulder movement is considered the accessory one, we can conclude that realization of a two-joint movement of the upper-limb distal part is based on superposition of CMCs related to basic movements (main and accessory). Neirofiziologiya/Neurophysiology, Vol. 41, No. 1, pp. 48–56, January–February, 2009.     

Susceptibility of the filbertworm (Cydia latiferreana, Lepidoptera: Tortricidae) and filbert weevil (Curculio occidentalis, Coleoptera: Curculionidae) to entomopathogenic nematodes

The objective of this study was to determine the susceptibility of the two primary direct insect pests of hazelnuts in Oregon to three species of entomopathogenic nematodes. The entomopathogenic nematodes (Heterorhabditis marelatus Pt. Reyes, Steinernema carpocapsae All and Steinernema kraussei L137) were used in laboratory soil bioassays to determine their virulence against filbertworm, Cydia latiferreana (Walsingham) (Lepidoptera: Tortricidae) and filbert weevil, Curculio occidentalis (Casey) (Coleoptera: Curculionidae). All three nematode species were infective in laboratory bioassays. Infectivity ranged from 73-100% and 23-85% for filbertworm and filbert weevil, respectively. Field results were similar to those found in the laboratory with filbertworm larvae being more susceptible to nematode infection.     

Identification of a novel inhibitory actin-capping protein binding motif in CD2-associated protein

CD2-associated protein (CD2AP) is a scaffold molecule that plays a critical role in the maintenance of the kidney filtration barrier. Little, however, is understood about its mechanism of function. We used mass spectrometry to identify CD2AP-interacting proteins. Many of the proteins that we identified suggest a role for CD2AP in endocytosis and actin regulation. To address the role of CD2AP in regulation of the actin cytoskeleton, we focused on characterizing the interaction of CD2AP with actin-capping protein CP. We identified a novel binding motif LXHXTXXRPK(X)6P present in CD2AP that is also found in its homolog Cin85 and other capping protein-associated proteins such as CARMIL and CKIP-1. CD2AP inhibits the function of capping protein in vitro. Therefore, our results support a role of CD2AP in the regulation of the actin cytoskeleton.     

Silencing urokinase in the ventral tegmental area in vivo induces changes in cocaine-induced hyperlocomotion

Serine proteases in the nervous system have functional roles in neural plasticity. Among them, urokinase-type plasminogen activator (uPA) exerts a variety of functions during development, and is involved in learning and memory. Furthermore, psychostimulants strongly induce uPA expression in the mesolimbic dopaminergic pathway. In this study, doxycycline-regulatable lentiviruses expressing either uPA, a dominant-negative form of uPA, or non-regulatable lentiviruses expressing small interfering RNAs (siRNAs) targeted against uPA have been prepared and injected into the ventral tegmental area (VTA) of rat brains. Over-expression of uPA in the VTA induces doxycycline-dependent expression of its receptor, uPAR, but not its inhibitor, plasminogen activator inhibitor-1 (PAI-1). uPAR expression in the VTA is repressed upon silencing of uPA with lentiviruses expressing siRNAs. In addition, over-expression of uPA in the VTA promotes a 15-fold increase in locomotion activity upon cocaine delivery. Animals expressing the dominant-negative form of uPA did not display such hyperlocomotor activity. These cocaine-induced behavioural changes, associated with uPA expression, could be suppressed in the presence of doxycycline or uPA-specific siRNAs expressing lentiviruses. These data strongly support the major role of urokinase in cocaine-mediated plasticity changes.     

Symposia

Sleep and Biological Rhythms -     

A reevaluation of the key factors that influence tomato fruit softening and integrity

The softening of fleshy fruits, such as tomato (Solanum lycopersicum), during ripening is generally reported to result principally from disassembly of the primary cell wall and middle lamella. However, unsuccessful attempts to prolong fruit firmness by suppressing the expression of a range of wall-modifying proteins in transgenic tomato fruits do not support such a simple model. 'Delayed Fruit Deterioration' (DFD) is a previously unreported tomato cultivar that provides a unique opportunity to assess the contribution of wall metabolism to fruit firmness, since DFD fruits exhibit minimal softening but undergo otherwise normal ripening, unlike all known nonsoftening tomato mutants reported to date. Wall disassembly, reduced intercellular adhesion, and the expression of genes associated with wall degradation were similar in DFD fruit and those of the normally softening 'Ailsa Craig'. However, ripening DFD fruit showed minimal transpirational water loss and substantially elevated cellular turgor. This allowed an evaluation of the relative contribution and timing of wall disassembly and water loss to fruit softening, which suggested that both processes have a critical influence. Biochemical and biomechanical analyses identified several unusual features of DFD cuticles and the data indicate that, as with wall metabolism, changes in cuticle composition and architecture are an integral and regulated part of the ripening program. A model is proposed in which the cuticle affects the softening of intact tomato fruit both directly, by providing a physical support, and indirectly, by regulating water status.     

Enhancement of Pig Embryonic Implants in Factor VIII KO Mice: A Novel Role for the Coagulation Cascade in Organ Size Control

Very little is known about the mechanisms that contribute to organ size differences between species. In the present study, we used a mouse model of embryonic pig tissue implantation to define the role of host Factor VIII in controlling the final size attained by the implant. We show here that pig embryonic spleen, pancreas, and liver all grow to an increased size in mice that are deficient in the Factor VIII clotting cascade. Similar results were obtained using the transplantation model after treatment with the low molecular weight heparin derivative Clexane which markedly enhanced transplant size. Likewise, enhanced size was found upon treatment with the direct thrombin inhibitor Dabigatran, suggesting that organ size regulation might be mediated by thrombin, downstream of Factor VIII. Considering that thrombin was shown to mediate various functions unrelated to blood clotting, either directly by cleavage of protease-activated receptors (PARs) or indirectly by cleaving osteopontin (OPN) on stroma cells, the role of PAR1 and PAR4 antagonists as well as treatment with cleaved form of OPN (tcOPN) were tested. While the former was not found to have an impact on overgrowth of embryonic pig spleen implants, marked reduction of size was noted upon treatment with the (tcOPN). Collectively, our surprising set of observations suggests that factors of the coagulation cascade have a novel role in organ size control.