So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

Reproductive loss in high-producing dairy cattle: where will it end?

Conventional approaches to chemical sensors have
traditionally made use of a “lock-and-key” design,
wherein a specific receptor is synthesized in order to
strongly and highly selectively bind the analyte of
interest.1-6 A related approach involves exploiting a
general physicochemical effect selectively toward a
single analyte, such as the use of the ionic effect in
the construction of a pH electrode. In the first
approach, selectivity is achieved through recognition
of the analyte at the receptor site, and in the second,
selectivity is achieved through the transduction
process in which the method of detection dictates
which species are sensed. Such approaches are appropriate
when a specific target compound is to be
identified in the presence of controlled backgrounds
and interferences. However, this type of approach
requires the synthesis of a separate, highly selective
sensor for each analyte to be detected. In addition,
this type of approach is not particularly useful for
analyzing, classifying, or assigning human value
judgments to the composition of complex vapor
mixtures such as perfumes, beers, foods, mixtures of
solvents, etc.

/pdf/cross-reactive-chemical-sensor-arrays-38dz1buu0b.pdf

Cross-reactive chemical sensor arrays.

Interrelationships between energy balance and postpartum reproductive function in dairy cattle.

https://hal.archives-ouvertes.fr/hal-01173575/document

Invited review: Body condition score and its association with dairy cow productivity, health, and welfare

Influence of negative energy balance on cyclicity and fertility in the high producing dairy cow.

http://oro.open.ac.uk/9672/1/Wathesetal07DAE.pdf

Differences between primiparous and multiparous dairy cows in the inter-relationships between metabolic traits, milk yield and body condition score in the periparturient period.

During early pregnancy the bovine embryo must produce a protein called interferon tau which inhibits the development of the luteolytic mechanism. Failure to inhibit luteolysis is the major cause of pregnancy loss in cows. The embryo must produce sufficient quantities of interferon tau by about day 16 to prevent luteolysis. Its ability to achieve this is largely dependent on the pattern of maternal progesterone production. A late rise in progesterone after ovulation or poor progesterone secretion during the luteal phase results in the development of poor embryos capable of producing little or no interferon tau at the critical time. The embryo inhibits luteolysis by preventing development of oxytocin receptors on the luminal epithelium of the uterine endometrium and thus oxytocin-induced secretion of PGF2 alpha and by the induction of a prostaglandin synthesis inhibitor within the endometrium. In sheep it has been hypothesised that interferon tau acts to inhibit endometrial oestrogen receptors and thus oestrogen-induced up-regulation of oxytocin receptors. In cows, the embryo inhibits the development of oxytocin receptors and the initiation of luteolysis without causing any change in uterine oestrogen receptors. Thus in the cow, the mechanism by which interferon tau inhibits oxytocin receptor development remains to be determined.

The regulation of interferon-tau production and uterine hormone receptors during early pregnancy.

Alteration of the polyunsaturated fatty acid (PUFA) composition of milk by dietary supplementation of cows may be beneficial to human health. However, dietary PUFAs may influence synthesis of both prostaglandins and steroid hormones. This study examined the effects of dietary PUFAs on reproductive parameters in lactating cows. Cows were fed an isoenergetic control ration (n = 8) or a diet supplemented with LinPreme (n = 7) or SoyPreme (n = 8). These proprietary feeds are derived from linseed or soybeans and contain high concentrations of linolenic acid (LNA, n-3) or linoleic acid (LA, n-6) protected PUFA, respectively. Both PUFA-supplemented diets reduced plasma progesterone, particularly in the early luteal phase, and increased the number of medium-sized (5-10 mm in diameter) follicles. The diameter of the first dominant follicle, insulin-like growth factor I (IGF-I) concentrations at oestrus and cholesterol concentrations were all higher in cows fed a diet supplemented with LA (n-6) than in cows that did not receive this supplement. In cows fed a diet supplemented with LNA (n-3), there was an increase in oestradiol during the follicular phase. Diet had no effect on non-esterified fatty acid or insulin concentrations, or on the duration of the oestrous cycle. The plasma concentration of 13,14,dihydro-15 keto PGF(2alpha) after administration of 50 iu oxytocin was unaffected by diet on day 15 and day 16 of the oestrous cycle, but showed a greater response on day 17 in the LA (n-6) supplemented group. Therefore, the PUFA content of the diet can influence both ovarian and uterine function in cows. However, further studies using larger numbers of cows are required to test whether fertility is also affected by such diets.

/pdf/effects-of-dietary-polyunsaturated-fatty-acids-on-ovarian-3afksaaqoo.pdf

Effects of dietary polyunsaturated fatty acids on ovarian and uterine function in lactating dairy cows.

This study examined the expression patterns of oxytocin and steroid receptors in the bovine endometrium during the oestrous cycle and early pregnancy to elucidate their respective roles in the regulation of luteolysis and the maternal recognition of pregnancy. In Expt 1, uterine biopsies were collected from four cows throughout three oestrous cycles each, to provide daily samples. In Expt 2, uterine tissue was collected on days 12, 14, 16 and 18 of the oestrous cycle (n = 20) or early pregnancy (n = 16). Oxytocin receptor, oestrogen receptor alpha and progesterone receptor mRNAs were localized by in situ hybridization, and localization of oestrogen receptor and progesterone receptor was confirmed by immunocytochemistry. All three receptors showed time- and cell-specific expression patterns. Oestrogen receptor alpha increased in all regions at oestrus but high concentrations were also found in the luminal epithelium during the mid-luteal phase and in the deep glands throughout the oestrous cycle. Progesterone receptor expression was higher in the stroma than it was in the types of epithelial cell, and increased expression was observed at oestrus and during the early luteal phase. The cyclical upregulation of oxytocin receptors in the luminal epithelium on about day 16 was not related to preceding changes in the endometrial expression of either oestradiol alpha or progesterone receptors. During early pregnancy, oxytocin receptor expression was suppressed. Oestrogen receptor a concentrations increased in the non-pregnant cows and decreased in the pregnant cows between days 16 and 18, but these changes followed rather than preceded the upregulation of oxytocin receptors in the non-pregnant cows. It is concluded that the initial upregulation of oxytocin receptors in the luminal epithelium, which triggers luteolysis, is not associated directly with changes in expression of oestrogen receptor alpha.

/pdf/expression-of-oxytocin-oestrogen-and-progesterone-receptors-2k5rt5iwmy.pdf

D C Wathes

Papers

Influence of negative energy balance on cyclicity and fertility in the high producing dairy cow.

Differences between primiparous and multiparous dairy cows in the inter-relationships between metabolic traits, milk yield and body condition score in the periparturient period.

The regulation of interferon-tau production and uterine hormone receptors during early pregnancy.

Effects of dietary polyunsaturated fatty acids on ovarian and uterine function in lactating dairy cows.

Expression of oxytocin, oestrogen and progesterone receptors in uterine biopsy samples throughout the oestrous cycle and early pregnancy in cows