Fixed effect genetic analysis of a diallel cross in dry beans (Phaseolus vulgaris L.)

Summary A full diallel cross among four diverse homozygous strains of dry edible beans (Phaseolus vulgaris L.) was evaluated for yield, protein content, and culinary quality traits in the F₂ and F₃ generations in two locations. Interpretation of diallel effects [Method 1 Model I] using a fixed-effect genetic model made it possible to combine data from two generations into a single analysis and quantify the relative contributions of additive and dominance genetic effects to general (GCA) and specific (SCA) combining abilities. GCA was found to arise from three potential sources: additive effects, dominance interactions at homozygous loci, and average dominance interactions in hybrids involving the parent in question. SCA was found to be a function solely of dominance. Additive effects were the primary determinant of GCA and were highly significant. Specific dominance interactions were significant for seed yield, cooked bean moisture content, and texture but not for protein content. Texture was the only trait for which the additive-dominance model failed to provide an adequate fit to the data, suggesting that texture is significantly affected by epistatic interaction. One cross (Brazil-2 × Sanilac) was identified that exhibited a large heterotic effect for seed yield although the parents' additive effects were nonsignificant. Such a nicking effect was attributed to complementation between the two parents.Cooperative investigations of the Agricultural Research Service, U.S. Department of Agriculture and Michigan State University, East Lansing, MI 48824. Part of a thesis submitted by the senior author in partial fulfillment of the requirements for the Ph.D. degree at Michigan State University. Approved for publication by the Michigan Agricultural Experiment Station as Journal Article No. 11791. Research supported by USAID under a Title XII Bean/Cowpea CRSP and cooperative with Washington State University, Pullman, WA99164     

Behavioural responses of juvenile cuttlefish (Sepia officinalis) to local water movements

Physiological studies have shown that the epidermal head and arm lines in cephalopods are a mechanoreceptive system that is similar to the fish and amphibian lateral lines (Budelmann BU, Bleckmann H. 1988. A lateral line analogue in cephalopods: Water waves generate microphonic potentials in the epidermal head lines of Sepia officinalis and Lolliguncula brevis. J. Comp. Physiol. A 164:1-5.); however, the biological significance of the epidermal lines remains unclear. To test whether cuttlefish show behavioural responses to local water movements, juvenile Sepia officinalis were exposed to local sinusoidal water movements of different frequencies (0.01-1000 Hz) produced by a vibrating sphere. Five behavioural responses were recorded: body pattern changing, moving, burrowing, orienting, and swimming. Cuttlefish responded to a wide range of frequencies (20-600 Hz), but not to all of the frequencies tested within that range. No habituation to repeated stimuli was seen. Results indicate that cuttlefish can detect local water movements (most likely with the epidermal head and arm lines) and are able to integrate that information into behavioural responses.     

Association of macrosomia with perinatal and postneonatal mortality among First Nations people in Quebec

Background

High prevalence of infant macrosomia (up to 36%, the highest in the world) has been reported in some First Nations communities in the Canadian province of Quebec and the eastern area of the province of Ontario. We aimed to assess whether infant macrosomia was associated with elevated risks of perinatal and postneonatal mortality among First Nations people in Quebec.

Methods

We calculated risk ratios (RRs) of perinatal and postneonatal mortality by birthweight for gestational age, comparing births to First Nations women (n = 5193) versus women whose mother tongue is French (n = 653 424, the majority reference group) in Quebec 1991–2000.

Results

The prevalence of infant macrosomia (birthweight for gestational age > 90th percentile) was 27.5% among births to First Nations women, which was 3.3 times (confidence interval [CI] 3.2–3.5) higher than the prevalence (8.3%) among births to women whose mother tongue is French. Risk ratios for perinatal mortality among births to First Nations women were 1.8 (95% CI 1.3–2.5) for births with weight appropriate for gestational age, 4.1 (95% CI 2.4–7.0) for small-for-gestational-age (< 10th percentile) births and < 1 (not significant) for macrosomic births compared to births among women whose mother tongue is French. The RRs for postneonatal mortality were 4.3 (95% CI 2.7–6.7) for infants with appropriate-for-gestational-age birthweight and 8.3 (95% CI 4.0–17.0) for infants with macrosomia.

Interpretation

Macrosomia was associated with a generally protective effect against perinatal death, but substantially greater risks of postneonatal death among births to First Nations women in Quebec versus women whose mother tongue is French.A trend toward higher birthweights has emerged in recent decades.^1–3 Reflected in this trend is a rise in the prevalence of infant macrosomia, commonly defined as either a birthweight greater than 4000 g or a birthweight for gestational age greater than the 90th percentile relative to a fetal growth standard.^4–8 Maternal obesity, impaired glucose tolerance and gestational diabetes mellitus are important risk factors for infant macrosomia^9,10 and are known to afflict a much higher proportion of people in Aboriginal populations than in the general population.^11–14 This is true especially for Aboriginal populations in which a traditional lifestyle has changed to a less physically active, modern lifestyle in recent decades. A high prevalence of infant macrosomia (up to 36%, which, to the best of our knowledge, is the highest in the world) has been reported in some First Nations communities of Quebec and eastern Ontario in Canada.^15–17 However, little is known about the implications of this high prevalence for perinatal and infant health of First Nations people in these regions. We examined whether infant macrosomia was associated with increased risk for perinatal and postneonatal death among First Nations infants in Quebec.