Fine‐scale acoustic telemetry reveals unexpected lake trout,Salvelinus namaycush,spawning habitats in northern Lake Huron,North America

Previous studies of lake trout, Salvelinus namaycush, spawning habitat in the Laurentian Great Lakes have used time‐ and labour‐intensive survey methods and have focused on areas with historic observations of spawning aggregations and on habitats prejudged by researchers to be suitable for spawning. As an alternative, we used fine‐scale acoustic telemetry to locate, describe and compare lake trout spawning habitats. Adult lake trout were implanted with acoustic transmitters and tracked during five consecutive spawning seasons in a 19–27 km² region of the Drummond Island Refuge, Lake Huron, using the VEMCO Positioning System. Acoustic telemetry revealed discrete areas of aggregation on at least five reefs in the study area, subsequently confirmed by divers to contain deposited eggs. Notably, several identified spawning sites would likely not have been discovered using traditional methods because either they were too small and obscure to stand out on a bathymetric map or because they did not conform to the conceptual model of spawning habitat held by many biologists. Our most unique observation was egg deposition in gravel and rubble substrates located at the base of and beneath overhanging edges of large boulders. Spawning sites typically comprised <10% of the reef area and were used consistently over the 5‐year study. Evaluation of habitat selection from the perspective of fish behaviour through use of acoustic transmitters offers potential to expand current conceptual models of critical spawning habitat.     

Fine screening potato (Solanum) species germplasm for tuber calcium

A representative sample of the US potato germplasm collection was screened in the greenhouse for ability to accumulate tuber calcium. Germplasm with very high and very low calcium accumulation capacity has been identified by progressively screening for extremes among species, among populations (accessions), and finally among genotypes (i.e., fine screening). Among accessions, the bestS. gourlayi andmicrodontum populations averaged more than six-fold greater tuber calcium than the poorestS. kurtzianum population. When screening was performed at the genotype level, the best individuals ofgourlayi andmicrodontum had over eight-fold greater calcium than the poorestkurtzianum individual. When grown in the field, calcium levels ofS. microdontum selections were confirmed to be significantly higher thantuberosum cultivars. When selected genotypes were intercrossed and their progeny were compared to their original populations, mean tuber calcium was significantly changed in the intended direction of selection forS. kurtzianum (made lower) andS. microdontum (made higher). These stocks are expected to be useful tools for study of the genetic and physiological bases of tuber calcium accumulation, refining screening methods, and breeding improved cultivars.     

Would you be happier if you were richer? A focusing illusion

The belief that high income is associated with good mood is widespread but mostly illusory. People with above-average income are relatively satisfied with their lives but are barely happier than others in moment-to-moment experience, tend to be more tense, and do not spend more time in particularly enjoyable activities. Moreover, the effect of income on life satisfaction seems to be transient. We argue that people exaggerate the contribution of income to happiness because they focus, in part, on conventional achievements when evaluating their life or the lives of others.     

An outbreak of sand impaction in postpartum dairy cows

Twenty-two cases of indigestion occurred in a 650-cow herd. Five cows had severe sand abomasal impaction, diagnosed by laparotomy. The pH of prepartum cows' urine was < 6.0 and of sand 8.0. Feed showed a dietary cation-anion difference < or = -110 mEq/kg. After feeding management corrections, no more cases were diagnosed.     

Immunohistochemical Localization of Glial and Neuronal Cell Markers in the Developing Bovine Brain*

In the present immunohistochemical study, the distribution and differentiation of glial and neuronal cells in bovine fetal brains (age range: between1–2 and7–8 months) was examined using antibodies against nervous system-specific proteins, i. e., glial fibrillary acidic protein (GFAP), vimentin, neuron specific enolase (NSE) and a neurofilament protein subunit (NF 200 kD).     

Phorate sulfoxidation by plant root extracts

Soybean root homogenates were found to oxidize phorate to phorate sulfoxide. Neither PO nor sulfone derivatives of phorate were detected. Fractionation of soybean root homogenate indicates that the enzyme(s) which oxidize phorate to the sulfoxide are largely (72%) in the 25,000g pellet. In vitro studies of the 25,000g pellet indicate a linear reaction rate at 34°C for periods of up to 2 h at the pH optimum of 5.5. Soybean and bean root 25,000g pellets were twice as active on a mg protein basis as those from barley, corn, wheat, sorghum and over ten times more active than tomato.In vitro studies indicate that Counter, disulfoton, fenthion, aldrin, heptachlor, piperonyl butoxide, sulfoxide, atrazine, SKF525A and p-chlorothioanisole when present at a 10:1 ratio with phorate significantly inhibited soybean root phorate sulfoxidation.