The dynamic influence of genetic variation on the susceptibility of sheep to gastrointestinal nematode infection.

The interaction between sheep and the nematode Teladorsagia circumcincta is one of the best understood of all host-parasite interactions. Following infection, there is considerable variation among lambs in the number of nematode eggs produced, the number of early fourth-stage larvae and the number of adult worms in the mucosa. These traits have a high variance to mean ratio (i.e. they are overdispersed or aggregated among hosts), they are skewed and approximately negative binomially distributed. The sources of overdispersion are differences among lambs in the ingestion of infective larvae and the immune response. Both forces can produce aggregation but their relative importance is unknown. The key components of variation can be identified by variance analysis. The sum of the average effects of polymorphic genes is known as additive genetic variation and this increases essentially from zero at one month of age to quite high values at six months of age. The major mechanism underlying genetic variation appears to be the differences among individuals in immune responses. Two of the major sources of variation in immune responses are differences in antigen recognition and differences in the type of cytokines produced. Genes that influence both these sources of variation are associated with differences in resistance to nematode infection. Therefore, much of the heterogeneity among animals in parasite transmission appears to be due to genetic variation in immune responsiveness.     

Biofilm hydrous manganese oxyhydroxides and metal dynamics in acid rock drainage

Biofilms in shallow, tailings-associated acid rock drainage (ARD) accumulated metals from May to September, indicating scavenging is stable within these biological solids over seasonal time frames. Results indicate a doubling (Mn, Cr) to over a 6-fold increase (Ni, Co) in biofilm metal concentrations. Biofilm oxygen and pH gradients measured over diel time scales with microelectrodes were observed to be both spatially and temporally variable, indicating that biofilms are highly dynamic geochemical environments. Biofilm metal retention and affinities were element specific indicating different processes control their sequestration. Metals were specifically scavenged by the organic constituents of the biofilm itself (Ni, Co) and associated biominerals of amorphous Mn oxyhydroxides (HMO; Ni, Co, and Cr). Results are consistent with sorption and coprecipitation processes controlling Ni and Co biofilm association, while Cr dynamics appear linked to those of Mn through redox processes. Biofilm HMO concentrations increased seasonally but showed significant diel fluctuations, indicating that both formation and dissolution processes occurred over rapid time scales in these biofilms. Biofilm HMO concentrations increased nocturnally but decreased during daylight hours to late afternoon minima. Under the geochemical conditions of the streams, observed HMO formation rates can only be explained by microbial catalysis. These results are the first to quantitatively examine microbial biofilm metal dynamics using microscale, geochemical techniques at both diel and seasonal time scales. They provide strong evidence for the significant role that microbial activity can play in metal geochemistry in natural environments.     

Electron microscopy may reveal structure of docosahexaenoic acid-rich oil within Schizochytrium sp

Schizochytrium sp. is an algae-like microorganism utilized for commercial production of docosahexaenoic acid (DHA)-rich oil and dried microalgae for use as a source of DHA in foods, feeds, and nutritional supplements. Electron microscopic analysis of whole cells of Schizochytrium sp. employing sample preparation by high-pressure freeze substitution suggests the presence of secondary and tertiary semicrystalline structures of triacylglycerols within the oil bodies in Schizochytrium sp. A fine secondary structure consisting of alternating light- and dark-staining bands was observed inside the oil bodies. Dark bands were 29 +/- 1 A in width, and light bands were 22 +/- 1 A in width. The tertiary (three-dimensional) structure may be a multilayered ribbon-like structure which appears coiled and interlaced within the oil body. In freeze-fracture photomicrographs, Schizochytrium oil bodies exhibited fracture planes with terraces averaging 52 +/- 7 A in height which could correspond to the combined width of two halves of two light bands and one dark band observed in the high-pressure freeze substitution photomicrographs. The results suggest that triacylglycerols within Schizochytrium sp. oil bodies may be organized in a triple chain-length structure. High-pressure freeze substitution electron micrographs of two other highly unsaturated oil-producing species of microalgae, Thraustochytrium sp. and Isochrysis galbana, also revealed this fine structure, whereas microalgae containing a higher proportion of saturated oil did not. The results suggest that the staining pattern is not an artifact of preparation and that the triple chain-length conformation of triacylglycerols in Schizochytrium sp. oil bodies may be caused by the unique fatty acid composition of the triacylglycerols.     

A 4 K to 20 K rotational-cooling magnetic refrigerator capable of 1mW to > 1W operation

The low-temperature, magnetic entropy of certain single-crystal paramagnetic materials, eg DyPO₄ changes dramatically as the crystal rotates in a magnetic field. A new magnetic refrigerator design based on the anisotropic nature of such materials is presented. The key advantages of the rotational-cooling concept are: a single, rotary motion is required; magnetic field shaping is not a problem because the entire working material is in a constant field; and the size of the refrigerator is smaller than other comparable magnetic refrigerators because the working material is entirely inside the magnet at all times. The main disadvantage of the rotational-cooling concept is that small-dimension single crystals are required.     

Descriptive, theoretical, and behavioral characteristics of subdoctoral school psychologists.

Reports an analysis of theoretical and behavioral characteristics of a group of applicants and enrollees to an advanced National Defense Education Act Institute held for school psychologists in 1967. Data collected are discussed in relationship to the training, background, theoretical orientation preferences, work load and time allocation to alternate school psychology activities, and behavioral characteristics of applicants and enrollees. Findings suggest that theoretical orientation does appear to effect dimensions of school psychology practice. Factor analyses and step-wise regressions were completed on both paper-pencil measures and observational data obtained from video tape analysis. Results suggest that school psychologists have been recruited for the most part from the ranks of teachers and counselors within the public school setting. Traditional and novel predictors and multiple criteria are discussed in relationship to the emergence of a task-oriented social-learning model for school psychology training and practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Editorial: Ave, Atque, Vale.

Presents the current author's "hail and farewell" as editor of Professional Psychology, a post which he has served for the past 6 years. Congratulations are extended to the new editor Norman Abeles. The author notes that he has simply attempted to build upon the solid foundation that Donald Freedheim, the founding editor of Professional Psychology, "so ably established". (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distributive justice development and social class.

Two studies assessed distributive justice development in lower- and middle-class children attending social-class-integrated schools. In Exp I, 28 middle- and 28 lower-class (MC and LC) White children from kindergarten and Grade 3 were given the Distributive Justice Scale and a vocabulary test. Results show that regardless of grade, LC Ss lagged behind MC Ss in distributive justice development, even when vocabulary was controlled. In Exp II, 32 MC and 32 LC Black Ss from kindergarten and Grade 3 were given the same measures plus sociometric peer ratings. Results replicated those of Exp I. Peer ratings indicate that LC Ss were chosen most often for negative sociometric questions. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Malignant tumors of the small intestine

Primary malignant tumors of the small intestine are uncommon. The average annual incidence rate over a period of 30 years in Saskatchewan was 0.7 and 0.6 per 100,000 for male and females, respectively. The 209 patients who comprise the series represent 1.6% of the total number who had gastrointestinal cancers over the same period. The distribution of the tumors by site and histologic type is described. Both carcinoid and adenocarcinomatous tumors of the small intestine are associated with a high incidence of primary malignant neoplasms in other sites (17.0 and 20.3%, respectively). One patient with Peutz-Jeghers syndrome is of interest because of the malignant change which occurred in more than one of the small bowel polyps and because of consequent liver metastases. The reason for the poor prognosis in noncarcinoid small bowel malignant neoplasms is probably due to late diagnosis. The five-year disease-free survival in these tumors was 22.5%. Malignant carcinoids had a better overall five-year survival rate of 64%. For those confined to the bowel wall, the five-year survival rate was 73%, compared to 59% for those extending to nodes or metastasizing to distant organs.     

The assessment of anxiety by physiological behavioral measures.

There is little research to support the contention that clearly defined patterns of physiological-behavioral responses associated with anxiety arousal can be distinguished from other arousal patterns. Intercorrelations among physiological measures of anxiety obtained under either resting states or under stress are generally low. No studies have been reported in which several measures of behavior were obtained simultaneously with a variety of physiological measures under conditions likely to be fear arousing. From Psyc Abstracts 36:02:2HN34M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)