Ultrastructural aspects of early immune damage to Taenia crassiceps metacestodes

Siebert, A. E. Jr., Good A. H. and Simmons J. E. 1978. Ultrastructural aspects of early immune damage to Taenia crassiceps metacestodes. International Journal for Parasitology8: 45–53. Changes in the ultrastructure of the tegument and subtegumental cells of intraperitoneally implanted Taenia crassiceps metacestodes were studied by transmission electron microscopy over a 4-week period. Death of metacestodes without involvement of host inflammatory cells is indicated initially by vacuolization of the larval tegument followed by loss of the tegument and subsequent death of the larvae. Changes in the tegument involve loss of the glycocalyx, reduction in the numbers of mitochondria and microtriches present, and loss of secretory capacity. Subtegumental cells show an accumulation of secretory vacuoles and marked disruption of nuclear morphology. Tegument damage is attributed to a complement-mediated lysis of the outer tegument membrane and death of the larvae probably results from loss of tegument function.     

Human fecal flora: variation in bacterial composition within individuals and a possible effect of emotional stress.

Data are presented on the distribution of 101 bacterial species and subspecies among 1,442 isolates from 25 fecal specimens from three men on: (i) their normal diet and normal living conditions, (ii) normal living conditions but eating the controlled metabolic diet designed for use in the Skylab simulation and missions, and (iii) the Skylab diet in simulated Skylab (isolation) conditions. These bacteria represent the most numerous kinds in the fecal flora. Analyses of the kinds of bacteria from each astronaut during the 5-month period showed more variation in the composition of the flora among the individual astronauts than among the eight or nine samples from each person. This observation indicates that the variations in fecal flora reported previously, but based on the study of only one specimen from each person, more certainly reflect real differences (and not daily variation) in the types of bacteria maintained by individual people. The proportions of the predominant fecal species in the astronauts were similar to those reported earlier from a Japanese-Hawaiian population and were generally insensitive to changes from the normal North American diet to the Skylab diet; only two of the most common species were affected by changes in diet. However, one of the predominant species (Bacteroides fragilis subsp. thetaiotaomicron) appeared to be affected during confinement of the men in the Skylab test chamber. Evidence is presented suggesting that an anger stress situation may have been responsible for the increase of this species simultaneously in all of the subjects studied. Phenotypic characteristics of some of the less common isolates are given. The statistical analyses used in interpretation of the results are discussed.     

Leukocyte migration inhibitory factor (LMIF) production in unidirectional mixed lymphocyte cultures.

Puromycin treatment of lymphocytes was used to develop a one-way test for leukocyte migration inhibitory factor (LMIF) production in the mixed lymphocyte culture (MLC) reaction. Lymphocytes incubated with this protein synthesis inhibitor induced a vigorous mediator production by nontreated allogeneic cells, being themselves unable to respond to stimulator cells. When puromycin-treated cells were stimulated with the mitogens PHA, ConA, or PWM, overall protein and DNA synthesis were significantly decreased with concomitant abolishment of LMIF production. Viability of stimulator lymphocytes was found to be essential for generation of the mediator in MLC reaction.     

Mapping genes for resistance to Leptosphaeria maculans in Brassica juncea.

Blackleg disease of crucifers, caused by the fungus Leptosphaeria maculans, is a major concern to oilseed rape producers worldwide. Brassica species containing the B genome have high levels of resistance to blackleg. Brassica juncea F2 and first-backcross (B1) populations segregating for resistance to a PG2 isolate of L. maculans were created. Segregation for resistance to L. maculans in these populations suggested that resistance was controlled by two independent genes, one dominant and one recessive in nature. A map of the B. juncea genome was constructed using segregation in the F2 population of a combination of restriction fragment length polymorphism (RFLP) and microsatel lite markers. The B. juncea map consisted of 325 loci and was aligned with previous maps of the Brassica A and B genomes. The gene controlling dominant resistance to L. maculans was positioned on linkage group J13 based on segregation for resistance in the F2 population. This position was confirmed in the B1 population in which the resistance gene was definitively mapped in the interval flanked by pN199RV and sB31143F. The provisional location of the recessive gene controlling resistance to L. maculans on linkage group J18 was identified using a subset of informative F2 individuals.     

Diet selection by European hares (Lepus europaeus) in the alpine zone of the Snowy Mountains, Australia

European hares (Lepus europaeus) are grazers and open grassland specialists that are replaced in mountain areas of their natural range in the northern hemisphere by browsing/intermediate feeding mountain hares (Lepus timidus), but in their introduced range in the southern hemisphere, occupy the alpine zone. We used micro-histological identification of plant fragments and germination of seeds in faecal pellets of L. europaeus from the Snowy Mountains, Australia, to determine diet. We asked whether diet shifted and/or diet breadth expanded in response to seasonally reduced food availability, particularly during winter. If so, did the constraints of food availability in the alpine zone lead to the diet mirroring that of L. timidus in its native alpine habitat. The diet of L. europaeus was dominated by grasses, herbs and shrubs. The main diet items in summer were grasses (70 %) and herbs (28 %). Grasses declined in the diet between summer and autumn when herbs increased to co-dominance, with a further change after establishment of the winter snowpack to a greater preponderance of shrubs (43 % compared with a maximum of 3 % in snow-free months). L. europaeus selected a wider range of plants in winter (59 species compared with 39 in summer) and diet was significantly more variable in winter than in autumn or summer (and in autumn than summer). We concluded that the persistence of L. europaeus in alpine areas of the southern hemisphere is testament to their ability to expand their dietary breadth to occupy mountain climatic zones normally occupied by L. timidus.     

Synthetic RNA Silencing of Actinorhodin Biosynthesis in Streptomyces coelicolor A3(2)

We demonstrate the first application of synthetic RNA gene silencers in Streptomyces coelicolor A3(2). Peptide nucleic acid and expressed antisense RNA silencers successfully inhibited actinorhodin production. Synthetic RNA silencing was target-specific and is a new tool for gene regulation and metabolic engineering studies in Streptomyces.     

Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.