Alkaloid toxins in endophyte-infected grasses.

Grasses infected with clavicipitaceous fungi have been associated with a variety of diseases including classical ergotism in humans and animals, fescue foot and summer syndrome in cattle, and rye-grass staggers in sheep. During the last decade it has been recognized that many of these fungal infections are endophytic; a fungal endophyte is a fungus that grows entirely within the host plant. Inspection of field collections and herbarium specimens has revealed that such infections are widespread in grasses. The chemistry associated with these grass-fungal interactions has proved to be interesting and complex, as each grass-fungal pair results in a unique "fingerprint" of various alkaloids, of which some are highly toxic to herbivores. In many cases the presence of an endophyte appears to benefit the plant by increasing drought resistance, or by increasing resistance to attack by insects, thus improving the overall survivability of the grass. This review will focus on alkaloids that have been reported in endophyte-infected grasses.     

Activation of beef-heart cytochrome c oxidase by cardiolipin and analogues of cardiolipin

Beef-heart cytochrome c oxidase lacking endogenous lipids can be prepared by cholate-mediated exchange with dimyristoylphosphatidylcholine (Powell, G. L., Knowles, P. F. and Marsh, D. (1985) Biochim. Biophys. Acta 816, 191-194). These preparations retained practically no endogenous cardiolipin (less than 0.19 mol cardiolipin per mol of oxidase) but in Tween 80 they retained unaltered electron transport activity. Resupplementation of the dimyristoylphosphatidylcholine-substituted cytochrome oxidase with cardiolipin and cardiolipin analogues with different numbers of acyl chains or with a methylated headgroup enhanced the activity of the reconstituted enzyme to an extent dependent on the structure of the cardiolipin derivative. The Eadie-Hofstee plot showed biphasic kinetic behavior for all reconstituted preparations, even those completely lacking cardiolipin. This biphasic substrate dependence of the kinetics was simulated using the model of Brzezinski, P. and Malmstr?m, B. G. (Proc. Natl. Acad. Sci. USA 83 (1986) 4282-4286), which implicates two interconverting enzyme conformations in the proton transport step. The activation of cytochrome c oxidase by the cardiolipin analogues could be explained in terms of an electrostatic enhancement of the surface concentrations of both cytochrome c and protons, and a facilitated interconversion between the two enzyme conformations.     

The surface microstructure of marine and terrestrial isopoda (Crustacea,Peracarida)

Summary The microstructure of the surface of thirteen marine littoral and two terrestrial isopods was investigated by scanning electron microscopy. A great diversity of surface ornamentation is present, including non-sensory microscales, pits, tubercles, and ridges, and sensory tricorns, pit organs, pores, papillae and setae. Microscales are common features of the integument surface; their shape and size are highly variable. Tricorns were not observed on the marine littoral isopods. Several hitherto undescribed structures were observed including spade-like projections from the tergite surface of Oniscus asellus, hair-like filaments associated with the microscales of Jaera and ridged conical protuberances on Edotea triloba and E. montosa. The possible function of certain surface microstructures is discussed.     

Ultrastructure and isolation of glyoxysomes (microbodies) in zoospores of the fungusentophlyctis sp.

Summary A correlative approach, involving light and electron microscopic, cytochemical, and biochemical techniques, was used to study the structure and function of microbodies in zoospores ofEntophlyctis sp. The same population of microbodies already existing in the zoosporangium appeared to be segregated into zoospore initials during cytoplasmic cleavage. Microbodies laid at the anterior end of zoospores and were part of an organized assemblage of organelles, the microbody-lipid globule complex. In the microbody-lipid globule complex, endoplasmic reticulum occurred on the surface of the lipid globules toward the zoospore's exterior, and the microbody, subtended by mitochondria, was appressed to the opposite surface of the lipid globule. The organization of the microbody-lipid globule complex changed as the zoospore swam and encysted. As lipid globules coalesced, the microbody-lipid globule complex became disorganized. After lipid globule coalescence was completed, the microbody-lipid globule complex regained its order, and several microbodies were clustered adjacent to a single lipid globule. The microbodies persisted even in the encysted zoospore, but they were found on all sides of the lipid globule.Microbodies isolated from zoospores contained catalase as well as malate synthase and isocitrate lyase, two enzymes of the glyoxylate cycle. When zoospores encysted greater activities of these glyoxylate cycle enzymes could be detected. The presence of glyoxylate cycle enzymes and the close association between the microbody and lipid globule suggest that microbodies function as glyoxysomes in zoospores and encysted zoospores. The functional significance of the morphological organization of the microbody-lipid complex is discussed in terms of energy production and the conversion of storage lipid into structural components of the cell.     

Modifying mosquitoes to suppress disease transmission: Is the long wait over?

For more than 50 years it has been a dream of medical entomologists and public health workers to control diseases like malaria and dengue fever by modifying, through genetics and other methods, the arthropods that transmit them to humans. A brief synopsis of the history of these efforts as applied to mosquitoes is presented; none proved to be effective in reducing disease prevalence. Only in the last few years have novel approaches been developed or proposed that indicate the long wait may be over. Three recent developments are particularly promising: CRISPR-Cas9 driven genetic modification, shifting naturally occurring allele frequencies, and microbe-based modifications. The last is the furthest along in implementation. Dengue fever incidence has been reduced between 40% and 96% in 4 different regions of the world where Wolbachia-infected Aedes aegypti have been established in the field. It is not yet clear how sustainable such control programs will prove to be, but there is good reason for optimism. In light of this, the time is ripe for reinvigorated research on vectors, especially genetics. Vector-borne diseases primarily affect under-developed countries and thus have not received the attention they deserve from wealthier countries with well-developed and funded biomedical research establishments.     

Retinol-binding protein 4 is expressed in chondrocytes of developing mouse long bones: implications for a local role in formation of the secondary ossification center

Retinol-binding protein 4 (Rbp4) is the major carrier of retinol in the bloodstream, a retinoid whose metabolites influence osteogenesis, chondrogenesis and adipogenesis. Rbp4 is mainly produced in the liver where it mobilizes hepatic retinol stores to supply other tissues. However, Rbp4 is also expressed in several extrahepatic tissues, including limbs, where its role is largely unknown. This study aimed to identify the cellular localization of Rbp4 to gain insight into its involvement in limb development and bone growth. Using immunohistochemistry, we discovered that Rbp4 was present in a variety of locations in developing embryonic and postnatal mouse hindlimbs. Rbp4 was present in a restricted population of epiphyseal chondrocytes and perichondral cells correlating to the future region of secondary ossification. With the onset of secondary ossification, Rbp4 was detected in chondrocytes of the resting zone and in chondrocytes that bordered invading cartilage canals and the expanding front of ossification. Rbp4 was less abundant in proliferating chondrocytes involved in primary ossification. Our data implicate the involvement of chondrocytic Rbp4 in bone growth, particularly in the formation of the secondary ossification center of the limb.     

Tuberculosis masquerading as malignancy: a multimodality approach to the correct diagnosis – a case report

BACKGROUND: Extrapulmonary tuberculosis is one of the great mimickers of medicine, and often masquerades as malignancy. As a result, patients may be referred to oncologists and surgeons for further evaluation and management, delaying the institution of appropriate anti-tuberculous drug therapy. CASE PRESENTATION: We present the case of a 21 year old man with tuberculous osteomyelitis, who was referred to the Bone and Soft Tissue Sarcoma Service at our institution with a provisional diagnosis of malignancy. Further investigation revealed extensive retroperitoneal abdominal and pelvic lymphadenopathy. The recognition of certain patterns on imaging, and finally the isolation of Mycobacterium tuberculosis from tissue samples obtained under image guidance, enabled the correct diagnosis to be made. CONCLUSION: This case highlights the importance of remaining cognisant of the protean manifestations of extrapulmonary tuberculosis, and illustrates the advantage of a clinically directed multi-modality imaging approach to diagnosis.