Histological Observations of Rotylenchulus reniformis on Gossypium longicalyx and Interspecific Cotton Hybrids

Observations on the development of reniform nematode (Rotylenchulus reniformis) on roots of Gossypium longicalyx, G. hirsutum, and two interspecific hybrids derived from them were made by light microscopy. Gossypium longicalyx is reported to be immune to reniform nematode, but the mechanism(s) for resistance are unknown. Penetration of G. longicalyx roots by female nematodes was confirmed, and incipient swelling of the females, indicating initiation of maturation of the reproductive system, was observed. Female maturation occurred up to the formation of a single embryo inside the female body but not beyond this point. In both hybrids, development was inhibited but progressed further than in the immune parent. Reactions ranged from highly compatible, with the formation of active syncytia and full development of females, to incompatible with little or no development of the female. Compatible plants showed characteristic hypertrophied cells, enlarged nuclei, dense cytoplasm, and partial dissolution of cell walls, whereas incompatible plant reactions included lignification of the cells adjacent to the nematode head, or the complete collapse and necrosis of the cells involved. The need to characterize reactions and to carefully select among the plants descended from the hybrids during the introgression process, as well as the importance of combining the results of reproduction tests with histological observation of the plant-nematode interactions, is discussed.     

Hybridization and the inheritance of female colour polymorphism in two ischnurid damselflies (Odonata: Coenagrionidae)

Female‐limited polychromatism is frequent in many species of Odonata. Ischnura elegans has three colour morphs: one male‐like coloured (androchrome) and two additional gynochrome brown morphs (infuscans and rufescens‐obsoleta morphs). A total of 19 progenies obtained from once‐mated females were reared in the laboratory in three generations. Results indicate that the colour morphs are controlled by the same genetic system as previously described for I. graellsii, i.e. an autosomal locus with female‐limited expression and with three alleles with a hierarchy of dominance (p^a > pⁱ > p°). Five interspecific crossings between female I. graellsii and male I. elegans, five crossings between hybrid females and male I. elegans and one crossing between female I. graellsii and a hybrid male further confirmed that the genetic system is the same in both species. A survey of morph frequencies in north‐west Spain revealed that I. elegans shows high variability in androchrome frequency (4–91%) between nearby populations, whereas in I. graellsii androchromes never are the majority morph (5–40%). The highest androchrome frequency in I. graellsii was found in populations closest to a locality where both species have hybridized, and that now has the highest androchrome frequency of I. elegans. We hypothesize that I. elegans genes have been incorporated into the genome of I. graellsii resulting in increased androchrome frequency in the latter species. Low androchrome frequency in I. elegans seems also related to the influence of I. graellsii genes. Therefore, we suggest that hybridization between both taxa is contributing to the temporal maintenance of contrasting androchrome frequencies in nearby populations. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85 , 471–481.     

Survey‐gap analysis in expeditionary research: where do we go from here?

Research expeditions into remote areas to collect biological specimens provide vital information for understanding biodiversity. However, major expeditions to little‐known areas are expensive and time consuming, time is short, and well‐trained people are difficult to find. In addition, processing the collections and obtaining accurate identifications takes time and money. In order to get the maximum return for the investment, we need to determine the location of the collecting expeditions carefully. In this study we used environmental variables and information on existing collecting localities to help determine the sites of future expeditions. Results from other studies were used to aid in the selection of the environmental variables, including variables relating to temperature, rainfall, lithology and distance between sites. A survey gap analysis tool based on ‘ED complementarity’ was employed to select the sites that would most likely contribute the most new taxa. The tool does not evaluate how well collected a previously visited site survey site might be; however, collecting effort was estimated based on species accumulation curves. We used the number of collections and/or number of species at each collecting site to eliminate those we deemed poorly collected. Plants, birds, and insects from Guyana were examined using the survey gap analysis tool, and sites for future collecting expeditions were determined. The south‐east section of Guyana had virtually no collecting information available. It has been inaccessible for many years for political reasons and as a result, eight of the first ten sites selected were in that area. In order to evaluate the remainder of the country, and because there are no immediate plans by the Government of Guyana to open that area to exploration, that section of the country was not included in the remainder of the study. The range of the ED complementarity values dropped sharply after the first ten sites were selected. For plants, the group for which we had the most records, areas selected included several localities in the Pakaraima Mountains, the border with the south‐east, and one site in the north‐west. For birds, a moderately collected group, the strongest need was in the north‐west followed by the east. Insects had the smallest data set and the largest range of ED complementarity values; the results gave strong emphasis to the southern parts of the country, but most of the locations appeared to be equidistant from one another, most likely because of insufficient data. Results demonstrate that the use of a survey gap analysis tool designed to solve a locational problem using continuous environmental data can help maximize our resources for gathering new information on biodiversity. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85 , 549–567.     

Inactivation and sensitization of tumor cells after transfection with gene Bax

Experiments on the transfection of cultured SKOV3 tumor cells of human ovarian adenocarcinoma and HeLa cells of human cervical carcinoma with gene Bax have demonstrated that SKOV3 cells are highly sensitive to the protein product of this gene, whereas the sensitivity of HeLa cells is substantially lower. HeLa cells obtained as a result of Bax transfection and subsequent selection are characterized by an extremely high Bax protein content and a hypersensitivity to doxorubicin. All Bax-transfected SKOV3 cells with an increased Bax content have died. In the SKOV3 cell line, a Bax exon 3 mutation has been found that corresponds to genotype G7/G9, whereas the native type of the Bax gene corresponds to genotype G8/G8. The results suggest that the G7/G9 mutation in Bax exon 3 deprives the Bax protein of proapoptotic activity.Translated from Molekulyarnaya Biologiya, Vol. 39, No. 1, 2005, pp. 40–47.Original Russian Text Copyright © 2005 by Rodina, Sladkova, Obuchova, Vezirkhanova, Moskaleva, Prusakova, Beletskii, Belushkina, Strelnikov, Ivanov, S. Severin, E. Severin.     

Thermoplastic starch modification during melt processing: Hydrolysis catalyzed by carboxylic acids

The melt processing of glycerol-plasticized starch in the presence of non-volatile carboxylic acids resulted in a progressive loss of its molar mass, because the residual moisture in the mixture induced an acid-catalyzed hydrolysis of the ether linkages in its polysaccharide chains. The study of this reaction provided a useful means of adjusting its course and thus of preparing starch materials with controlled properties.     

Applications of ATR-FTIR spectroscopic imaging to biomedical samples

FTIR spectroscopic imaging in ATR (Attenuated Total Reflection) mode is a powerful tool for studying biomedical samples. This paper summarises recent advances in the applications of ATR-FTIR imaging to dissolution of pharmaceutical formulations and drug release. The use of two different ATR accessories to obtain chemical images of formulations in contact with water as a function of time is demonstrated. The innovative use of the diamond ATR accessory allowed in situ imaging of tablet compaction and dissolution. ATR-FTIR imaging was also applied to obtain images of the surface of skin and the spatial distribution of protein and lipid rich domains was obtained. Chemical images of cross-section of rabbit aorta were obtained using a diamond ATR accessory and the possibility of in situ imaging of arterial samples in contact with aqueous solution was demonstrated for the first time. This experiment opens an opportunity to image arterial samples in contact with solutions containing drug molecules. This approach may help in understanding the mechanisms of treatment of atherosclerosis.