Structure—activity relationships for some organotin molluscicides

Bioassay data are reported for 12 organotin compounds, R₃SnX, against the adult snail, Biomphalaria glabrata, an intermediate host of schistosomiasis. The relationship between the molluscicidal activity and the nature of the R and X groups in the organotin compounds is discussed, as well as the possible mode of toxic action of these compounds.     

Ribotyping of Indian Isolates of <Emphasis Type="Italic">Pasteurella multocida</Emphasis> Based on 16S and 23S rRNA Genes

The applicability of ribotyping based on 16S and 23S rRNA was evaluated for molecular epidemiological studies. Forty-eight isolates of Pasteurella multocida isolated from different hosts and geographical locations and one reference isolate were ribotyped. Only four ribotypes were found. All the isolates including reference isolate from wild carnivores had the same ribotype, though they had different serotypes. The isolate from a tiger had one band in addition to the bands present in the major ribotype. The isolates from lions represented two ribotypes; of these ribotypes, one (r2) had an additional band of 3.6 kbp, which was absent in all other ribotypes. The second ribotype (r4) from a lion had one band missing (6 kbp) that was present in the other ribotypes. These isolates were further typed using ERIC-PCR and REP-PCR. With ERIC-PCR and REP-PCR, higher D values of 0.83 and 0.89 were obtained. The current study revealed that ribotyping is not a very efficient typing tool for use in molecular epidemiology for differentiation of isolates.     

Histology, immunohistochemistry and ultrastructure of the equine palatine tonsil

The palatine tonsils of five young horses formed 10-12 cm elongated follicular structures extending from the root of the tongue on either side to the base of the epiglottis and lateral to the glossoepiglottic fold. The stratified squamous non-keratinized epithelium of the outer surface was modified into crypts as reticular epithelium by heavy infiltration of lymphoid cells from underlying lymphoid follicles. In places, lymphoid tissue reaching almost to the surface and with only one to two cell layers intact was identified as the lymphoepithelium. Langerhans cells with Birbeck granules were interspersed between epithelial cells. Lymphoid tissue organized in lymphoid follicles constituted the parenchyma of the palatine tonsil. CD4-positive cells were more numerous and CD8-positive lymphocytes less numerous compared with their distribution in the lingual tonsil. B cells and macrophages were also more numerous than in the lingual tonsil and lectins showed a different pattern of attachment. M cells were not observed. High endothelial venules with well-developed vesiculo-vacuolar organelle had structural evidence of transendothelial and interendothelial migration of lymphocytes. Striated muscles as seen in the deeper lamina propria mucosae of the lingual tonsil were absent. The immunohistological and ultrastructural characteristics of the equine palatine tonsil are similar to those of humans but differ from those of the lingual tonsil and are consistent with a role as an effector and inductor immunological organ.     

A case study of capture-recapture methodology using scrapie surveillance data in Great Britain

We applied capture–recapture methodology (CRC) to data from three surveillance sources (statutory notification, abattoir survey (AS) and fallen stock (FS) survey) to estimate the number of holdings infected with scrapie in Great Britain and to assess the sensitivity of the surveillance network. Between January 1, 2002 and March 31, 2003, 144 holdings were identified by the three sources. Using CRC modelling techniques, we estimated a minimum lower bound for the total number of holdings infected as 642. A biologically plausible positive dependence between the statutory reporting and the fallen stock survey was found statistically significant. The sensitivity of the three sources combined was very low. The integration of the three overlapping sources provided a better understanding of the interactions within the surveillance network. However, the scarcity of the data and reduced overlapping among sources only allowed for very cautious inferences to be drawn about the true proportion of scrapie affected holdings in the national population. Future surveys and surveillance activities should be planned such that the resulting data can be used more effectively as part of CRC modelling approaches.     

Cell Membrane Stability in Relation to Drought Tolerance in Wheat Genotypes

Genotyptc differences in wheat were observed in cell membrane with respect to injury caused by osmotic shock created with 40 per cent polyethylene glycol-6000. In general, genotypes with high cell membrane injury also registered much reduction in leaf water potential and osmotic potential. Cell membrane injury measured at 25 days after germination was found to be related with genotypic performance under drought conditions in field. Cell membrane stability measurements of normal plants, even at a very early stage of growth, is reported as criteria for selecting drought tolerant wheat genotypes.     

Prevalent Serotypes of Pasteurella multocida Isolated from Different Animal and Avian Species in India

Identification and estimation of the prevalence of Pasteurella multocida organisms in different animal and avian species in India during November 2000 to July 2003 was carried out. Out of 418 samples collected from different outbreaks suspected to be caused by P. multocida, a total of 206 bacterial cultures were identified as P. multocida on the basis of cultural, morphological and biochemical characteristics. All the 206 cultures were isolated from different domestic animal species (cattle, buffalo, sheep, goat, pig and rabbit), avian species (chicken, duck, quail, turkey, goose) and wild animals such as leopard and deer. Serotyping of P. multocida cultures revealed the presence of various serotypes (A:1, A:3, A:1,3, A:4, B:2, D:1 and -:1) among the livestock population. P. multocida polymerase chain reaction (PCR) assay applied on different forms of bacterial cultures (bacterial culture lysate, direct bacterial colony and mixed bacterial culture lysate) yielded an amplified product of approximately 460 bp specific for P. multocida. The results of PCR assay correlated well with conventional methods of identification. The present investigation revealed the presence of varied serotypes among livestock and PCR assay was found to be useful for rapid, sensitive and specific diagnosis of pasteurellosis in animals and avian species.