Innate phase behavior in the desert locust,Schistocerca gregaria

Abstract Detailed aspects of the transition from the solitarious to the gregarious phase in the framework of locust ecology are undoubtedly most important for understanding locust phase polyphenism. Nevertheless, due to obvious difficulties in studying the solitarious phase in nature, such information is limited and mostly available from research carried out under laboratory conditions. In the current study, we examined the dispersal patterns of newly hatched locust nymphs in a laboratory setup that simulated seminatural conditions. This was carried out with no previous manipulation of the nymphs other than controlling their parental density. We comparatively tested the spatial distribution of newly hatched nymphs on perches located at different ranges within an emergence arena, and the expected Poisson (random) distribution. Hatchlings were found to disperse among the perches in a pattern significantly different from that expected by random. Irrespective of their parents’ phase, the observed distributions of all nymphs were clearly clumped, similar or close to those expected for gregarious locusts. It seems that rather than emerging with a parentally derived and predetermined phase, hatchlings have an independent default or innate behavioral state, which reflects at least tolerance if not attraction to conspecifics. The typical phase behavior may later become dominant under the appropriate environmental conditions. These results imply novel perspectives on locust phase transformation, which contribute to our understanding of the formation of locust crowds under field conditions. These should be considered in any rationale for developing a preventative management strategy of locust populations.     

Effect of Cyanophage Infection on CO2 Photoassimilation in Plectonema boryanum

Cyanophage infection effects a rapid and complete cessation of CO₂ photoassimilation in Plectonema cells. From the amount of infected cells lysed, it was established that this phenomenon cannot be ascribed to lysis of the host cells either from within or from without. The possibility that the effect is due to nitrogen starvation, induced secondarily by cyanophage multiplication, was ruled out when it was found that nitrogen supplementation did not influence the inhibition. It is suggested that the arrest of CO₂ photoassimilation is an integral part of the cyanophage infection cycle in P. boryanum. This idea is supported by the nondependence of the cyanophage-induced inhibition on the input multiplicity, by the light requirement for the inhibition, and by the fact that infected Plectonema cells with inhibited CO₂ photo-assimilation support normal multiplication of the cyanophage. The pattern of light requirement for this viral inhibition further supports this suggestion.     

Surface properties and reduced biofouling of graft-copolymers that possess oppositely charged groups

Microbial biofilms and their components present a major obstacle for ensuring the long-term effectiveness of membrane processes. Graft polymerization on membrane surfaces, in general, and grafting with oppositely charged monomers, have been shown to reduce biofouling significantly. In this study, surface forces and macromolecular properties of graft copolymers that possess oppositely charged groups were related to their potent antibiofouling behavior. Graft polymerization was performed using the negatively charged 3-sulphopropyl methacrylate (SPM) and positively charged [2-(methacryloyloxy)ethyl]-trimethylammonium (MOETMA) monomers to yield a copolymer layer on polyvinylidene fluoride (PVDF) surface. Quartz crystal microbalance with dissipation monitoring (QCM-D) technology was used to monitor the reduced adsorption of extracellular polymeric substances (EPS) extracted from a membrane bioreactor (MBR) wastewater treatment facility. Complemented measurements of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy provided evaluation of the antifouling properties of the surface. Increase in water content in grafted layer exposed to 100 mM aqueous NaCl solution was observed by QCM-D. Therefore, the grafted copolymer layer is swelled in the presence of 100 mM NaCl because of reversing of polymer self-association by counterions. Force measurements by atomic force microscopy (AFM) showed an increased repulsion between a carboxylate-modified latex (CML) particle probe and a modified PVDF surface, especially in the presence of 100 mM NaCl. The hydration and swelling of the grafted polymer layer are shown to repel EPS and reduce their adsorption. Delineating the surface properties of antifouling grafted layers may lead to the design of novel antifouling surfaces.     

Radiotherapy for Stage IIA seminoma: The Northern Israel Oncology Center Experience, 1971–2010

Aim

To evaluate treatment details, outcome, relapse rate and side-effects in Stage IIA seminoma irradiated and followed for a period of 39 years.

Background

Seminoma is a very radiosensitive disease and radiation therapy alone is able to achieve long-term disease-free survival, even in advanced Stage disease. Due to the lack of long-term prospective studies, it is of value to follow patients and try to determine the appropriate volume to be irradiated and the dose which can achieve total cure with minimal acute and chronic side-effects.

Patients and methods

A retrospective review of 24 Stage IIA seminoma patients irradiated between 1971 and 2010 was performed. All patients underwent orchiectomy and meticulous clinical, biochemical and radiological staging.

Results

Median age at diagnosis was 36 years and median follow-up was 84 months. A majority of patients received the “hockey-stick” irradiation schedule (para-aortic lymph nodes and hemi-pelvis) to a total dose of 2250–2500 cGy and a boost to radiologically involved nodes of 500–1000 cGy. Treatment was well-tolerated. Twenty-one (88%) patients are alive with no evidence of disease. Two patients died due to unknown causes, while one patient died due to head of the pancreas carcinoma, most probably radiation-induced.

Conclusions

In Stage II seminoma, radiotherapy can provide excellent results with low rates of toxicity. Reduction of total dose and size of fields without affecting the good results should be considered. Due to prolonged survival, awareness of second primary tumor is indicated.     

Mediterranean fruit fly as a potential vector of bacterial pathogens

The Mediterranean fruit fly (Ceratitis capitata) is a cosmopolitan pest of hundreds of species of commercial and wild fruits. It is considered a major economic pest of commercial fruits in the world. Adult Mediterranean fruit flies feed on all sorts of protein sources, including animal excreta, in order to develop eggs. After reaching sexual maturity and copulating, female flies lay eggs in fruit by puncturing the skin with their ovipositors and injecting batches of eggs into the wounds. In view of the increase in food-borne illnesses associated with consumption of fresh produce and unpasteurized fruit juices, we investigated the potential of Mediterranean fruit fly to serve as a vector for transmission of human pathogens to fruits. Addition of green fluorescent protein (GFP)-tagged Escherichia coli to a Mediterranean fruit fly feeding solution resulted in a dose-dependent increase in the fly's bacterial load. Flies exposed to fecal material enriched with GFP-tagged E. coli were similarly contaminated and were capable of transmitting E. coli to intact apples in a cage model system. Washing contaminated apples with tap water did not eliminate the E. coli. Flies inoculated with E. coli harbored the bacteria for up to 7 days following contamination. Fluorescence microscopy demonstrated that the majority of fluorescent bacteria were confined along the pseudotrachea in the labelum edge of the fly proboscis. Wild flies captured at various geographic locations were found to carry coliforms, and in some cases presumptive identification of E. coli was made. These findings support the hypothesis that the common Mediterranean fruit fly is a potential vector of human pathogens to fruits.     

Effect of adhesion to particles on the survival and activity of Nitrosomonas sp. and Nitrobacter sp.

The adhesion of Nitrosomonas sp. and Nitrobacter sp. cells isolated from fishpond sediment to different solid particles was studied. Nitrosomonas and Nitrobacter cells rapidly attached to particles of bentonite, calcium carbonate, amberlite, and fishpond sediment, however they did not adhere to phenyl-sepharose beads. The nitrifying activity of attached bacteria was greater than the activity of freely suspended cells or the activity of cells which have been detached from CaCO₃ particles. The enhancement in the nitrifying activity was rapid and was already observed within the first hour after attachment (which equals only 1/24 to 1/50 of the generation time of Nitrosomonas sp. or Nitrobacter sp. In addition, the survival of the attached bacteria under both anaerobic and under aerobic incubation was extended to weeks, compared to only a few days for the free cells. The presence of substrate (ammonia or nitrite) during the anaerobic incubation period was found not to affect the survival time of the bacteria. Finally, it was found that the attachment of Nitrosomonas and Nitrobacter cells to CaCO₃ particles affected the dispersal and sinking rate of these particles.     

Lithium nuclear magnetic resonance measurements in halotolerant bacterium Ba1

Measurements of relaxation times T₁ and T₂, were carried out on a high-salt- and low-salt-grown bacterial pellets of halotolerant bacterium B_a1. In our measurements, T₁ ? T₂ and both were frequency-independent. In the high-salt-grown pellet the relaxation time values were much shorter than in the case of low-salt growth medium. Intensity measurements show that only 55% of the lithium in the high-salt pellet is detected; for the low-salt pellet almost all the lithium is detected. Growth measurements were carried out on the B_a1. It is suggested that there is some form of adaptation of the bacteria to the growth medium. The adaptation is reflected in the lithium NMR results.     

Correlative histochemical and morphological study on the maturation of sensory ganglion cells in the rat

Summary In neonatal rats the sensory ganglion cells are uniform in size and in their stainability with hematoxylin and eosin. At this stage the cells differ, however, in the intensity of staining for RNA and for various enzyme activities. With maturation the ganglion cells differentiate into light (mostly large) cells, and dark (mostly small) cells. The differentiation is accompanied by changes in intensity of various enzyme activities. In sections stained for acid phosphatases and acetylcholine esterase, maturation was associated with a higher activity in the small than in the large cells, whereas with thiamine pyrophosphatase it was associated with a higher activity in the large than in the small neurones. With non-specific cholinesterase, maturation of all cells was accompanied by loss of activity in perikarya and increased activity in axons and satellite cells. With monoamine oxidase, the changes during maturation differed in the trigeminal from the spinal ganglion cells.The findings indicate that the difference between small and large cells might have a functional significance, the nature of which is discussed.