The surface topography and ultrastructure of the tegument and haptor of Pricea multae (Monogenea)

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and 1986. The surface topography and ultrastructure of the tegument and haptor of Pricea multae (Monogenea). International Journal for Parasitology 16: 581–589. Pricea multae is a gill parasite of Scomberomorus spp. In the present study, the surface specialization and ultrastructure of the tegument and haptor were examined in detail. The buccal cavity and the preoral pit bear uniciliated sensory endings. The genital atrium opens on the ventral surface whereas the vaginal pore opens on the dorsal surface of the anterior region. The general body surface is elevated by pits and folds together with papillae-like uniciliated sensory endings. Microvilli are uncommon.

The syncytium of the tegument is bounded by apical and basal plasma membranes. Some electron-dense granules and electron-lucent vesicles were observed exocytosing at the apical surface. The tegumental perikarya lie amongst the muscle blocks underneath the basal lamina. The body wall muscle fibres are non-striated consisting of thick and thin myofilaments. Each muscle fibre is limited by a sarcolemma and separated from neighbouring fibres by interstitial material.

The haptor possesses two rows of pincer-type clamps. The clamps may be withdrawn by muscles into cavity-like depressions. Electron-dense fibrils are embedded within the clamp sclerite matrix. The intrinsic muscles of the clamp include radial muscles enclosed within the basal lamina. The muscle fibres enclosed within the basal lamina of the clamp appear to differ from the body wall muscles by the absence of interstitial material, the possession of well defined gap junctions between the sarcolemma of adjacent muscle fibres, abundant sarcoplasmic reticulum and numerous mitochondria. The extrinsic muscles of the clamp presumably arise from the dorso-lateral surface of the haptor and are apparently connected to the tendon of the clamp. A cluster of gland cells occurs in the haptor beneath each clamp. The haptor is richly supplied with nerve fibres which are associated with groups of neurones. Each axon is non-myelinated and contains presumed neurosecretory granules. The peripheries of some of the large axons are subdivided by invaginations of the axon wall.     

Lack of lignin degradation by glucose oxidase-negative mutants of Phanerochaete chrysosporium

Glucose oxidase-negative (gox-) mutants of Phanerochaete chrysosporium were isolated after exposing conidia to UV irradiation. The gox- mutants exhibited little or no ability to degrade lignin (2-[14C]-synthetic lignin to 14CO2); however, they retained other secondary metabolic features such as the ability to conidiate and produce veratryl alcohol, suggesting that they are not pleiotropic for secondary metabolism. Lignin degradation activity was restored in gox+ revertants. These results, in support of earlier evidence, indicate that glucose oxidase activity plays an important role in lignin degradation by P. chrysosporium.     

Attempts to manipulate specific responses to induce resistance to Schistosoma mansoni in Kenyan baboons (Papio anubis)

Attempts were made to manipulate specific responses of baboons to protect them from infection with Schistosoma mansoni. In Experiment 1, eosinophilia was induced in naive baboons with Trichinella spiralis larvae given intravenously before intraperitoneal injection of globulin fractions from S. mansoni-infected baboon sera and subsequent percutaneous exposure to S. mansoni cercariae. In Experiment 2, baboons with 8- or 32-week-old primary S. mansoni infections received T. spiralis i.v. before an S. mansoni challenge. In experiments 3 to 5 respectively, naive baboons received intramuscularly before challenge: formalin-fixed S. mansoni schistosomula, with Bordetella pertussis as an adjuvant; a preparation of S. mansoni adult worm teguments; and a preparation of IgE-immune complexes obtained from S. mansoni-infected rat sera, with Freunds Complete Adjuvant. Minor, but statistically insignificant, protection was obtained in Experiments 2 (32-week infections) and 3, but was far less than that given by intact, irradiated living vaccines. There are signs on the horizon of non-living vaccines protecting rodents against S. mansoni infection and it would be prudent, as with drugs, to test these in primates before proceeding to man. The results of our experiments, though essentially negative, should help the design of any future vaccine trials in primates.     

Evaluation of biorational insecticides and DNA barcoding as tools to improve insect pest management in lablab bean (Lablab purpureus) in Bangladesh

Lablab bean (Lablab purpureus) is a popular vegetable crop in Bangladesh, but farmers growing this crop experience significant losses to insect pests despite heavy reliance on conventional insecticides. We conducted field studies to improve pest management in lablab bean by testing biorational insecticides as alternatives to conventional insecticides for the control of pod borers (Maruca vitrata) and aphids (Aphis craccivora), and characterizing flower-inhabiting thrips as an emerging pest in this crop. In field experiments, spinosad was the most promising biorational we tested, suppressing pod-boring caterpillars more effectively than thiamethoxam or quinalphos. In contrast, azadirachtin (neem) did not significantly suppress any of the insect pests we measured, although target aphid populations were generally low at our research site. Using DNA barcoding at the coxI locus combined with morphological identification, we found eight thrips taxa inhabiting lablab bean flowers, dominated by Megalurothrips usitatus and M. distalis/peculiaris. A preliminary regression analysis indicated that these flower-inhabiting thrips reduced lablab bean yield. Our results suggest that spinosad may be useful within lablab bean IPM programs, and that these programs will likely need to incorporate tactics against thrips to effectively protect yield. Finally, we found that DNA barcoding was a valuable tool for pest identification in an understudied crop and region, but that to reach its full potential will require an investment in more comprehensive reference libraries.     

The parasitic fly Nemorilla maculosa exploits host‐plant volatiles to locate the legume pod borer,Maruca vitrata

Nemorilla maculosa Meigen (Diptera: Tachinidae) is a solitary endoparasitoid of the legume pod borer, Maruca vitrata Fabricius (Lepidoptera: Crambidae), a key pest of cowpea, Vigna unguiculata (L.) Walp. (Fabaceae) in Africa. A colony of N. maculosa, introduced for experimental purposes from Taiwan to the laboratories of the International Institute of Tropical Agriculture (IITA) in Benin, was used for our studies. Olfactory reponses of N. maculosa to leaves of infested or uninfested cowpea and yellow peabush, Sesbania cannabina (Retz.) Pers. (Fabaceae), and to M. vitrata larvae were evaluated in a four‐arm olfactometer. For all combinations of odor sources, responses between naïve and oviposition‐experienced female flies did not differ. Nemorilla maculosa females were attracted by odors from uninfested leaves of yellow peabush and flowers of cowpea when compared with clean air, and they were attracted to plants damaged by M. vitrata with larvae removed. However, the female fly did not discriminate between odors from infested and uninfested plants. The parasitic fly N. maculosa proved well able to use volatile compounds from various host plants (peabush and cowpea) to locate its host, with a more pronounced attraction by the combination of host larvae and infested host plant parts. These findings are discussed in light of the prospective use of N. maculosa as a biological control agent against the legume pod borer.     

Analysis of tail-anchored protein translocation pathway in plants

Tail-anchored (TA) proteins are a special class of membrane proteins that carry out vital functions in all living cells. Targeting mechanisms of TA proteins are investigated as the best example for post-translational protein targeting in yeast. Of the several mechanisms, Guided Entry of Tail-anchored protein (GET) pathway plays a major role in TA protein targeting. Many in silico and in vivo analyses are geared to identify TA proteins and their targeting mechanisms in different systems including Arabidopsis thaliana. Yet, crop plants that grow in specific and/or different conditions are not investigated for the presence of TA proteins and GET pathway. This study majorly investigates GET pathway in two crop plants, Oryza sativa subsp. Indica and Solanum tuberosum, through detailed in silico analysis. 508 and 912 TA proteins are identified in Oryza sativa subsp. Indica and Solanum tuberosum respectively and their localization with respect to endoplasmic reticulum (ER), mitochondria, and chloroplast has been delineated. Similarly, the associated GET proteins are identified (Get1, Get3 and Get4) and their structural inferences are elucidated using homology modelling. Get3 models are based on yeast Get3. The cytoplasmic Get3 from O. sativa is identified to be very similar to yeast Get3 with conserved P-loop and TA binding groove. Three cytoplasmic Get3s are identified for S. tuberosum. Taken together, this is the first study to identify TA proteins and GET components in Oryza sativa subsp. Indica and Solanum tuberosum, forming the basis for any further experimental characterization of TA targeting and GET pathway mechanisms in crop plants.     

Influence of vanadate on glycolysis,intracellular sodium,and pH in perfused rat hearts

Vanadium compounds have been shown to cause a variety of biological and metabolic effects including inhibition of certain enzymes, alteration of contractile function, and as an insulin like regulator of glucose metabolism. However, the influence of vanadium on metabolic and ionic changes in hearts remains to be understood. In this study we have examined the influence of vanadate on glucose metabolism and sodium transport in isolated perfused rat hearts. Hearts were perfused with 10 mM glucose and varying vanadate concentrations (0.7100 M) while changes in high energy phosphates (ATP and phosphocreatine (PCr)), intracellular pH, and intracellular sodium were monitored using 31P and 23Na NMR spectroscopy. Tissue lactate, glycogen, and (Na+, K+)-ATPase activity were also measured using biochemical assays. Under baseline conditions, vanadate increased tissue glycogen levels two fold and reduced (Na+, K+)-ATPase activity. Significant decreases in ATP and PCr were observed in the presence of vanadate, with little change in intracellular pH. These changes under baseline conditions were less severe when the hearts were perfused with glucose, palmitate and b-hydroxybutyrate. During ischemia vanadate did not limit the rise in intracellular sodium, but slowed sodium recovery on reperfusion. The presence of vanadate during ischemia resulted in attenuation of acidosis, and reduced lactate accumulation. Reperfusion in the presence of vanadate resulted in a slower ATP recovery, while intracellular pH and PCr recovery was not affected. These results indicate that vanadate alters glucose utilization and (Na+, K+)-ATPase activity and thereby influences the response of the myocardium to an ischemic insult.