Ultralow oxygen treatment for control of Latrodectus hesperus (Araneae: Theridiidae) on harvested table grapes

The spider Latrodectus hesperus Chamberlin & Ivie (Araneae: Theridiidae) was subjected to low and ultralow oxygen (ULO) treatments at different temperatures. Complete control of the spiders was achieved in 24-h ULO treatments with 0.5% O2 or lower at 1 degrees C and in a 24-h low oxygen (2%) treatment at 15 degrees C. Oxygen level and temperature greatly affected spider mortality. At 1 degrees C, as oxygen level was decreased from 2 to 0.5%, spider mortality increased from 0 to 100%. At 2% O2, as temperature was increased from 1 to 15 degrees C, spider mortality increased from 0 to 100%. Grape clusters from two table grape (Vitis spp.) cultivars, 'Thompson Seedless' and 'Flame Seedless', were subjected to the 24-h ULO treatment with 0.5% O2 at 1 degrees C. The ULO treatment had no negative effects on grape quality. Because of the relatively short treatment time, effectiveness at low storage temperature and the easily attained oxygen level, we conclude that the ULO treatment have good potential to be implemented commercially for control of black widow spiders on harvested table grapes.     

Distribution and morphology of growth anomalies in Acropora from the Indo-Pacific

We assessed the distribution and prevalence of growth anomalies (GAs) in Acropora from French Frigate Shoals (Hawaii, USA), Johnston Atoll and Tutuila (American Samoa), developed a nomenclature for gross morphology, characterized GAs at the cellular level and obtained preliminary indices of their spatial patterns and progression within coral colonies. Acropora GAs were found in all 3 regions, but the distribution, variety and prevalence of Acropora GAs was highest in American Samoa. GAs were grouped into 7 gross morphologies (exophytic, bosselated, crateriform, nodular, vermiform, fimbriate or annular). On histology, GAs consisted of hyperplastic basal body wall (calicodermis, mesoglea and gastrodermis apposed to skeleton) with 3 distinct patterns of necrosis. There was no evidence of anaplasia or mitotic figures (common but not necessarily required morphologic indicators of neoplasia). Compared to normal tissues, GAs had significantly fewer polyps, zooxanthellae within the gastrodermis of the coenenchyme, mesenterial filaments and gonads but significantly more necrosis. On 2 colonies with GAs monitored at 2 points over 11 mo, numbers of GAs per colony increased from 0.9 to 3 times the original number seen, and significant clustering of GAs occurred within colonies. The evidence of GAs being true neoplasias (tumors) is mixed, so a cautionary approach is urged in use of morphologic terminology.     

The other cooperation problem: generating benefit

Understanding how cooperation evolves is central to explaining some core features of our biological world. Many important evolutionary events, such as the arrival of multicellularity or the origins of eusociality, are cooperative ventures between formerly solitary individuals. Explanations of the evolution of cooperation have primarily involved showing how cooperation can be maintained in the face of free-riding individuals whose success gradually undermines cooperation. In this paper I argue that there is a second, distinct, and less well explored, problem of cooperation that I call the generation of benefit. Focusing on how benefit is generated within a group poses a different problem: how is it that individuals in a group can (at least in principle) do better than those who remain solitary? I present several different ways that benefit may be generated, each with different implications for how cooperation might be initiated, how it might further evolve, and how it might interact with different ways of maintaining cooperation. I argue that in some cases of cooperation, the most important underlying “problem” of cooperation may be how to generate benefit, rather than how to reduce conflict or prevent free-riding.     

Synthesis of ethyl-(3R,5S)-dihydroxy-6-benzyloxyhexanoates via diastereo- and enantioselective microbial reduction: Cloning and expression of ketoreductase III from Acinetobacter sp. SC 13874

Previously we have demonstrated the reduction of ethyl and t-butyl diketoesters 1 to the corresponding syn-(3R,5S)-dihydroxy esters 2a by Acinetobacter sp. 13874. The syn-(3R,5S)-dihydroxy ester 2a was obtained with an enantiomeric excess (e.e.) of 99% and a diastereomeric excess (de) of 63%. In this report, we identified a gene encoding desired ketoreductase III which catalyzed the diastereoselective reduction of diketoesters 1 to syn-(3R,5S)-dihydroxy esters 2a and describe cloning and expression of ketoreductase III into Escherichia coli. Cells or extracts of recombinant E. coli efficiently reduced the diketoester 1 to the corresponding syn-(3R,5S)-dihydroxy ester 2a in 99.3% yield, 100% e.e., and 99.8% de.     

The proprotein convertase PCSK9 induces the degradation of low density lipoprotein receptor (LDLR) and its closest family members VLDLR and ApoER2

The proprotein convertase PCSK9 gene is the third locus implicated in familial hypercholesterolemia, emphasizing its role in cardiovascular diseases. Loss of function mutations and gene disruption of PCSK9 resulted in a higher clearance of plasma low density lipoprotein cholesterol, likely due to a reduced degradation of the liver low density lipoprotein receptor (LDLR). In this study, we show that two of the closest family members to LDLR are also PCSK9 targets. These include the very low density lipoprotein receptor (VLDLR) and apolipoprotein E receptor 2 (ApoER2) implicated in neuronal development and lipid metabolism. Our results show that wild type PCSK9 and more so its natural gain of function mutant D374Y can efficiently degrade the LDLR, VLDLR, and ApoER2 either following cellular co-expression or re-internalization of secreted human PCSK9. Such PCSK9-induced degradation does not require its catalytic activity. Membrane-bound PCSK9 chimeras enhanced the intracellular targeting of PCSK9 to late endosomes/lysosomes and resulted in a much more efficient degradation of the three receptors. We also demonstrate that the activity of PCSK9 and its binding affinity on VLDLR and ApoER2 does not depend on the presence of LDLR. Finally, in situ hybridization show close localization of PCSK9 mRNA expression to that of VLDLR in mouse postnatal day 1 cerebellum. Thus, this study demonstrates a more general effect of PCSK9 on the degradation of the LDLR family that emphasizes its major role in cholesterol and lipid homeostasis as well as brain development.     

Mobilisation of Ca2+ stores and flagellar regulation in human sperm by S-nitrosylation: a role for NO synthesised in the female reproductive tract

Generation of NO by nitric oxide synthase (NOS) is implicated in gamete interaction and fertilisation. Exposure of human spermatozoa to NO donors caused mobilisation of stored Ca(2+) by a mechanism that did not require activation of guanylate cyclase but was mimicked by S-nitroso-glutathione (GSNO; an S-nitrosylating agent). Application of dithiothreitol, to reduce protein -SNO groups, rapidly reversed the actions of NO and GSNO on [Ca(2+)](i). The effects of NO, GSNO and dithiothreitol on sperm protein S-nitrosylation, assessed using the biotin switch method, closely paralleled their actions on [Ca(2+)](i). Immunofluorescent staining revealed constitutive and inducible NOS in human oviduct and cumulus (the cellular layer investing the oocyte). 4,5-diaminofluorescein (DAF) staining demonstrated production of NO by these tissues. Incubation of human sperm with oviduct explants induced sperm protein S-nitrosylation resembling that induced by NO donors and GSNO. Progesterone (a product of cumulus cells) also mobilises stored Ca(2+) in human sperm. Pre-treatment of sperm with NO greatly enhanced the effect of progesterone on [Ca(2+)](i), resulting in a prolonged increase in flagellar excursion. We conclude that NO regulates mobilisation of stored Ca(2+) in human sperm by protein S-nitrosylation, that this action is synergistic with that of progesterone and that this synergism is potentially highly significant in gamete interactions leading to fertilisation.     

Hydrogen sulfide as an oxygen sensor in trout gill chemoreceptors

O2 chemoreceptors elicit cardiorespiratory reflexes in all vertebrates, but consensus on O2-sensing signal transduction mechanism(s) is lacking. We recently proposed that hydrogen sulfide (H2S) metabolism is involved in O2 sensing in vascular smooth muscle. Here, we examined the possibility that H2S is an O2 sensor in trout chemoreceptors where the first pair of gills is a primary site of aquatic O2 sensing and the homolog of the mammalian carotid body. Intrabuccal injection of H2S in unanesthetized trout produced a dose-dependent bradycardia and increased ventilatory frequency and amplitude similar to the hypoxic response. Removal of the first, but not second, pair of gills significantly inhibited H2S-mediated bradycardia, consistent with the loss of aquatic chemoreceptors. mRNA for H2S-synthesizing enzymes, cystathionine beta-synthase and cystathionine gamma-lyase, was present in branchial tissue. Homogenized gills produced H2S enzymatically, and H2S production was inhibited by O2, whereas mitochondrial H2S consumption was O2 dependent. Ambient hypoxia did not affect plasma H2S in unanesthetized trout, but produced a PO2-dependent increase in a sulfide moiety suggestive of increased H2S production. In isolated zebrafish neuroepithelial cells, the putative chemoreceptive cells of fish, both hypoxia and H2S, produced a similar approximately 10-mV depolarization. These studies are consistent with H2S involvement in O2 sensing/signal transduction pathway(s) in chemoreceptive cells, as previously demonstrated in vascular smooth muscle. This novel mechanism, whereby H2S concentration ([H2S]) is governed by the balance between constitutive production and oxidation, tightly couples tissue [H2S] to PO2 and may provide an exquisitely sensitive, yet simple, O2 sensor in a variety of tissues.     

Neurally-derived nitric oxide regulates vascular tone in pulmonary and cutaneous arteries of the toad, Bufo marinus

In this study, the role of nitric oxide (NO) in regulation of the pulmocutaneous vasculature of the toad, Bufo marinus was investigated. In vitro myography demonstrated the presence of a neural NO signaling mechanism in both arteries. Vasodilation induced by nicotine was inhibited by the soluble guanylyl cyclase (GC) inhibitor, 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one, and the NO synthase (NOS) inhibitor, N(omega)-nitro-l-arginine (l-NNA). Removal of the endothelium had no significant effect on the vasodilation. Furthermore, pretreatment with N(5)-(1-imino-3-butenyl)-l-ornithine (vinyl-l-NIO), a more specific inhibitor of neural NOS, caused a significant decrease in the nicotine-induced dilation. In the pulmonary artery only, a combination of l-NNA and the calcitonin gene-related peptide (CGRP) receptor antagonist, CGRP((8-37)), completely blocked the nicotine-induced dilation. In both arteries, the vasodilation was also significantly decreased by glibenclamide, an ATP-sensitive K(+) (K(+)(ATP)) channel inhibitor. Levcromakalim, a K(+)(ATP) channel opener, caused a dilation that was blocked by glibenclamide in both arteries. In the pulmonary artery, NO donor-mediated dilation was significantly decreased by pretreatment with glibenclamide. The physiological data were supported by NADPH-diaphorase histochemistry and immunohistochemistry, which demonstrated NOS in perivascular nerve fibers but not the endothelium of the arteries. These results indicate that the pulmonary and cutaneous arteries of B. marinus are regulated by NO from nitrergic nerves rather than NO released from the endothelium. The nitrergic vasodilation in the arteries appears to be caused, in part, via activation of K(+)(ATP) channels. Thus, NO could play an important role in determining pulmocutaneous blood flow and the magnitude of cardiac shunting.     

Exercise reduces arterial pressure augmentation through vasodilation of muscular arteries in humans

Exercise markedly influences pulse wave morphology, but the mechanism is unknown. We investigated whether effects of exercise on the arterial pulse result from alterations in stroke volume or pulse wave velocity (PWV)/large artery stiffness or reduction of pressure wave reflection. Healthy subjects (n = 25) performed bicycle ergometry. with workload increasing from 25 to 150 W for 12 min. Digital arterial pressure waveforms were recorded using a servo-controlled finger cuff. Radial arterial pressure waveforms and carotid-femoral PWV were determined by applanation tonometry. Stroke volume was measured by echocardiography, and brachial and femoral artery blood flows and diameters were measured by ultrasound. Digital waveforms were recorded continuously. Other measurements were made before and after exercise. Exercise markedly reduced late systolic and diastolic augmentation of the peripheral pressure pulse. At 15 min into recovery, stroke volume and PWV were similar to baseline values, but changes in pulse wave morphology persisted. Late systolic augmentation index (radial pulse) was reduced from 54 +/- 3.9% at baseline to 42 +/- 3.7% (P < 0.01), and diastolic augmentation index (radial pulse) was reduced from 37 +/- 1.8% to 25 +/- 2.9% (P < 0.001). These changes were accompanied by an increase in femoral blood flow (from 409 +/- 44 to 773 +/- 48 ml/min, P < 0.05) and an increase in femoral artery diameter (from 8.2 +/- 0.4 to 8.6 +/- 0.4 mm, P < 0.05). In conclusion, exercise dilates muscular arteries and reduces arterial pressure augmentation, an effect that will enhance ventricular-vascular coupling and reduce load on the left ventricle.