Biological traits of eastern sand darter (Ammocrypta pellucida) in the lower Thames River,Canada, with comparisons to a more southern population

Eastern sand darter (Ammocrypta pellucida) is listed as Threatened under the Canadian Species at Risk Act. Little relevant biological information is available for most Canadian populations and only limited information is available for populations in the United States. To supplement the paucity of information, this study collected biological information on eastern sand darter during field surveys in 2006–2007 from 10 sites in the lower Thames River, Ontario, Canada. Collected data were used to estimate critical life history traits including: longevity, fecundity, clutch size and number, growth, survival, age‐at‐first‐maturity and cohort age structure. Longevity was 3+ years, with age‐at‐first‐maturity being 1+ for both sexes. Examination of egg sizes from preserved females in 2007 showed a bimodal distribution, suggesting two spawning occurrences of 71 eggs each. Quantitative comparison of lower Thames River biological information with a more southerly eastern sand darter population in the Little Muskingum River, Ohio, demonstrated little variation between the populations. Data comparisons suggest that localised environmental factors are affecting biological traits (growth), in particular water temperature that may be controlled by differences in riparian cover and/or groundwater input.     

A micromethod for evaluating turkey lymphocyte response to phytomitogens.

A microculture system used in conjunction with a semiautomatic sample harvester is described to determine the in vitro properties of turkey peripheral blood lymphocytes. By this new procedure, multiple tests were done rapidly, relatively few cells were used, and results were highly reproducible. Analysis indicated that the conditions for optimal concanavalin A (con A) stimulation, as measured by incorporation of 3H-thymidine (3H-TdR) included (a) 2 times 10(6) cells per culture in RPMI 1640 medium in the absence of any serum; (b) 0.4 mug of con A per culture, incubated in flat-bottom microtitration wells for 72 hours at 37 C; and (c) 1 muCi of 3H-TdR per culture added 12 to 24 hours before termination. Conditions for optimal stimulation with pokeweed mitogen were similar to those used for con A. The exceptions were that 1 times 10(6) cells per culture were incubated in round-bottom microtitration wells. The pokeweed mitogen gave the highest degree of stimulation when used at a concentration of 80 mug per culture.     

Small mammals in agricultural landscapes: Opposing responses to farming practices and landscape complexity

Organic farming often counteracts the decline of various taxa owing to agricultural intensification, but little is known about the relative importance of local management and landscape context for small mammals. We examined the abundance, species richness and diversity of small mammal communities in 22 organically and conventionally managed winter wheat fields pairwise located along a gradient of landscape structural complexity (41–94% arable land). Complex landscapes significantly increased small mammal abundance and (with marginal significance) species richness and diversity, but only in conventional fields, whereas organic farming increased small mammals in simple landscapes. These results indicate the importance of landscape complexity for small mammal populations in an intensified agriculture. Analyses at multiple spatial scales (100 m, 250 m, 500 m radii around focal fields), showed opposing responses of the three most abundant species to landscape complexity. Apodemus agrarius PALLAS abundance increased with increasing landscape complexity at a spatial scale of 100 m, whereas Microtus arvalis PALLAS and Sorex araneus L. abundances decreased with increasing landscape complexity at spatial scales of 100 m and 500 m, respectively, suggesting species-specific ecological needs as well as functional spatial scales for conservation management. In conclusion, agri-environmental measures for small mammals such as organic farming are most effective in simple landscapes, while complex landscapes presumably function as source habitats and can compensate for local agricultural intensification in conventional fields.     

Testing hypotheses about fecundity, body size and maternal condition in fishes

Recent research suggests that maternal condition positively influences the number of eggs spawned in fishes. These studies commonly choose a priori to use body length rather than weight as an explanatory variable of offspring production, even though weight is usually the better predictor of fecundity. We are concerned that consistent exclusion of body weight as a predictor of egg production inflates the variance in fecundity attributable to maternal condition. By analysing data on three populations of Atlantic cod (Gadus morhua, Gadidae) and 10 populations of brook trout (Salvelinus fontinalis, Salmonidae), we illustrate the need for a statistically defensible method of model selection to distinguish the effects of maternal condition on egg production from the effects of body size alone. Forward stepwise regression and null model analyses reveal how length‐based regressions can significantly over‐estimate correlations between condition and fecundity, leading us to conclude that the effect of condition on egg productivity may not be as ubiquitous or as biologically important as previously thought. Our work underscores the need for greater statistical clarity in analyses of the effects of maternal condition on reproductive productivity in fishes.     

Phosphonic analogues of morphactins. Part V: Peptides containing 9-aminofluoren-9-ylphosphine oxides

Di- and tripeptides containing P-terminal 9-aminofluoren-9-ylphosphine oxides were synthesised and evaluated for herbicidal activity using Spirodela oligorriza (Kurz.) Hegelm. The glycylglycyl and threonyl peptides showed high activity as measured by the reduction of dry matter.