Survival of Vibrio parahaemolyticus in cold smoked fish

Fresh samples of mullet (Mugil cephalus) and oil sardines (Sardinella longiceps) obtained from a fish market were subjected to cold smoking. Some of the samples harboured low levels of Vibrio parahaemolyticus. After cold smoking, however, many samples showed relatively high levels of V. parahaemolyticus suggesting that a small population of naturally occuring organisms could multiply to significant levels during the process of cold smoking or during subsequent storage at room temperature. Nevertheless, smoke components were observed to exert an inhibitory effect on V. parahaemolyticus in broth. Salt concentration 1% appeared to increase the sensitivity of V. parahaemolyticus to smoke components.     

Intracellular interference of tick-borne flavivirus infection by using a single-chain antibody fragment delivered by recombinant Sindbis virus.

A single-chain antibody fragment that identifies a neutralizing epitope on the envelope protein of louping ill and some other tick-borne flaviviruses was previously expressed in soluble form from bacteria and shown to be functionally active in vitro. To see whether or not the single-chain antibody could bind and inactivate infectious virus in vivo, we have used recombinant Sindbis virus as a delivery vehicle for intracellular expression of the antibody fragment. The variable genes and interchain linker encoding the single-chain antibody were cloned into a double subgenomic Sindbis virus expression vector to generate recombinant Sindbis virus. Infection with this recombinant Sindbis virus provided high-level cytoplasmic expression of the antibody fragment in mammalian cells. We demonstrate (i) that the antibody fragment was antigen binding and (ii) that louping ill virus infectivity was significantly reduced in the presence of intracellular antibody expressed by the superinfecting recombinant Sindbis virus.     

Contrasting Role of Temperature in Structuring Regional Patterns of Invasive and Native Pestilential Stink Bugs

Objectives

Assessment and identification of spatial structures in the distribution and abundance of invasive species is important for unraveling the underlying ecological processes. The invasive agricultural insect pest Halyomorpha halys that causes severe economic losses in the United States is currently expanding both within United States and across Europe. We examined the drivers of H. halys invasion by characterizing the distribution and abundance patterns of H. halys and native stink bugs (Chinavia hilaris and Euschistus servus) across eight different spatial scales. We then quantified the interactive and individual influences of temperature, and measures of resource availability and distance from source populations, and their relevant spatial scales. We used Moran’s Eigenvector Maps based on Gabriel graph framework to quantify spatial relationships among the soybean fields in mid-Atlantic Unites States surveyed for stink bugs.

Findings

Results from the multi-spatial scale, multivariate analyses showed that temperature and its interaction with resource availability and distance from source populations structures the patterns in H. halys at very broad spatial scale. H. halys abundance decreased with increasing average June temperature and distance from source population. H. halys were not recorded at fields with average June temperature higher than 23.5°C. In parts with suitable climate, high H. halys abundance was positively associated with percentage developed open area and percentage deciduous forests at 250m scale. Broad scale patterns in native stink bugs were positively associated with increasing forest cover and, in contrast to the invasive H. halys, increasing mean July temperature. Our results identify the contrasting role of temperature in structuring regional patterns in H. halys and native stink bugs, while demonstrating its interaction with resource availability and distance from source populations for structuring H. halys patterns.

Conclusion

These results help predicting the pest potential of H. halys and vulnerability of agricultural systems at various regions, given the climatic conditions, and its interaction with resource availability and distance from source populations. Monitoring and control efforts within parts of the United States and Europe with more suitable climate could focus in areas of peri-urban developments with deciduous forests and other host plants, along with efforts to reduce propagule pressure.     

Bromelain induces cardioprotection against ischemia-reperfusion injury through Akt/FOXO pathway in rat myocardium

Bromelain (Br), a proteolytic enzyme extracted from the stem of the pineapple, is known to possess anti-inflammatory activity and has been shown to reduce blood viscosity, prevent the aggregation of blood platelets, and improve ischemia-reperfusion (I/R) injury in a skeletal muscle model. We investigated the capacity of Br to limit myocardial injury in a global I/R model. Adult male Sprague-Dawley rats were divided into two groups: control (PBS) and Br at 10 mg/kg in PBS administered via intraperitoneal injection (twice/day) for 15 consecutive days. On day 16, the hearts were excised and subjected to 30 min of global ischemia followed by 2 h of reperfusion. Br treatment showed higher left ventricular functional recovery throughout reperfusion compared with the controls [maximum rate of rise in intraventricular pressure (dP/dt max), 2,225 vs. 1,578 mmHg/s at 2 h reperfusion]. Aortic flow was also found to be increased in Br treatment when compared with that in untreated rats (11 vs. 1 ml). Furthermore, Br treatment reduced both the infarct size (34% vs. 43%) and the degree of apoptosis (28% vs. 37%) compared with the control animals. Western blot analysis showed an increased phosphorylation of both Akt and FOXO3A in the treatment group compared with the control. These results demonstrated for the first time that Br triggers an Akt-dependent survival pathway in the heart, revealing a novel mechanism of cardioprotective action and a potential therapeutic target against I/R injury.     

Solubilization of fish proteins using immobilized microbial cells

Cells of Bacillus megaterium, Aeromonas hydrophila, and Pseudomonas marinoglutinosa were immobilized in calcium alginate. The immobilized cells secreted protease when held in fish meat suspension in water. The enzyme synthesis by the entrapped cells was supported by small amounts of soluble nutrients present in the meat. The secreted protease solubilized the fish meat, solubilization being optimum at pH range of 7.5 to 9.5 and at 50 degrees C. Under these conditions immobilized B. megaterium was most efficient giving 30% solubilization of the meat, followed by A. hydrophila (18%), while immobilized P. marinoglutinosa was less effective. The optimum ratio of fish meat to beads was about 4:3 for B. megaterium and A. hydrophila. The beads had a storage life of 30 days at 4 degrees C. The results suggested potential for use of immobilized microbial cells having extracellular protease activity to enhance solubility of waste proteins. A prototype reactor with beads holding assembly was fabricated which could recover the beads from the meat slurry after the treatment.     

Virulence of Mycobacterium tuberculosis depends on lipoamide dehydrogenase, a member of three multienzyme complexes

Mycobacterium tuberculosis (Mtb) adapts to persist in a nutritionally limited macrophage compartment. Lipoamide dehydrogenase (Lpd), the third enzyme (E3) in Mtb's pyruvate dehydrogenase complex (PDH), also serves as E1 of peroxynitrite reductase/peroxidase (PNR/P), which helps Mtb resist host-reactive nitrogen intermediates. In contrast to Mtb lacking dihydrolipoamide acyltransferase (DlaT), the E2 of PDH and PNR/P, Lpd-deficient Mtb is severely attenuated in wild-type and immunodeficient mice. This suggests that Lpd has a function that DlaT does not share. When DlaT is absent, Mtb upregulates an Lpd-dependent branched-chain keto acid dehydrogenase (BCKADH) encoded by pdhA, pdhB, pdhC, and lpdC. Without Lpd, Mtb cannot metabolize branched-chain amino acids and potentially toxic branched-chain intermediates accumulate. Mtb deficient in both DlaT and PdhC phenocopies Lpd-deficient Mtb. Thus, Mtb critically requires BCKADH along with PDH and PNR/P for pathogenesis. These findings position Lpd as a potential target for anti-infectives against Mtb.     

The structure of neurexin 1α reveals features promoting a role as synaptic organizer

α-neurexins are essential synaptic adhesion molecules implicated in autism spectrum disorder and schizophrenia. The α-neurexin extracellular domain consists of six LNS domains interspersed by three EGF-like repeats and interacts with many different proteins in the synaptic cleft. To understand how α-neurexins might function as synaptic organizers, we solved the structure of the neurexin 1α extracellular domain (n1α) to 2.65 ?. The L-shaped molecule can be divided into a flexible repeat I (LNS1-EGF-A-LNS2), a rigid horseshoe-shaped repeat II (LNS3-EGF-B-LNS4) with structural similarity to so-called reelin repeats, and an extended repeat III (LNS5-EGF-B-LNS6) with controlled flexibility. A 2.95 ? structure of n1α carrying splice insert SS#3 in LNS4 reveals that SS#3 protrudes as a loop and does not alter the rigid arrangement of repeat II. The global architecture imposed by conserved structural features enables α-neurexins to recruit and organize proteins in distinct and variable ways, influenced by splicing, thereby promoting synaptic function.