Use of the EM algorithm to detect QTL affecting multiple-traits in an across half-sib family analysis

QTL detection experiments in livestock species commonly use the half-sib design. Each male is mated to a number of females, each female producing a limited number of progeny. Analysis consists of attempting to detect associations between phenotype and genotype measured on the progeny. When family sizes are limiting experimenters may wish to incorporate as much information as possible into a single analysis. However, combining information across sires is problematic because of incomplete linkage disequilibrium between the markers and the QTL in the population. This study describes formulæ for obtaining MLEs via the expectation maximization (EM) algorithm for use in a multiple-trait, multiple-family analysis. A model specifying a QTL with only two alleles, and a common within sire error variance is assumed. Compared to single-family analyses, power can be improved up to fourfold with multi-family analyses. The accuracy and precision of QTL location estimates are also substantially improved. With small family sizes, the multi-family, multi-trait analyses reduce substantially, but not totally remove, biases in QTL effect estimates. In situations where multiple QTL alleles are segregating the multi-family analysis will average out the effects of the different QTL alleles.     

The Expression and Activation of Protease‐Activated Receptor‐2 Correlate with Skin Color

Skin color results from the production and distribution of melanin in the epidermis. The protease‐activated receptor‐2 (PAR‐2), expressed on keratinocytes but not on melanocytes, is involved in melanosome uptake via phagocytosis, and modulation of PAR‐2 activation affects skin color. The pattern of melanosome distribution within the epidermis is skin color‐dependent. In vitro, this distribution pattern is regulated by the ethnic origin of the keratinocytes, not the melanocytes. Therefore, we hypothesized that PAR‐2 may play a role in the modulation of pigmentation in a skin type‐dependent manner. We examined the expression of PAR‐2 and its activator, trypsin, in human skins with different pigmentary levels. Here we show that PAR‐2 and trypsin are expressed in higher levels, and are differentially localized in highly pigmented, relative to lightly pigmented skins. Moreover, highly pigmented skins exhibit an increase in PAR‐2‐specific protease cleavage ability. Microsphere phagocytosis was more efficient in keratinocytes from highly pigmented skins, and PAR‐2 induced phagocytosis resulted in more efficient microsphere ingestion and more compacted microsphere organization in dark skin‐derived keratinocytes. These results demonstrate that PAR‐2 expression and activity correlate with skin color, suggesting the involvement of PAR‐2 in ethnic skin color phenotypes.     

AMPKα loss promotes KRAS-mediated lung tumorigenesis

AMP-activated protein kinase (AMPK) is a critical sensor of energy status that coordinates cell growth with energy balance. In non-small cell lung cancer (NSCLC) the role of AMPKα is controversial and its contribution to lung carcinogenesis is not well-defined. Furthermore, it remains largely unknown whether long non-coding RNAs (lncRNAs) are involved in the regulation of AMPK-mediated pathways. Here, we found that loss of AMPKα in combination with activation of mutant KRAS^G12D increased lung tumour burden and reduced survival in Kras^LSLG12D/+/AMPKα^fl/fl mice. In agreement, functional in vitro studies revealed that AMPKα silencing increased growth and migration of NSCLC cells. In addition, we identified an AMPKα-modulated lncRNA, KIMAT1 (ENSG00000228709), which in turn regulates AMPKα activation by stabilizing the lactate dehydrogenase B (LDHB). Collectively, our study indicates that AMPKα loss promotes KRAS-mediated lung tumorigenesis and proposes a novel KRAS/KIMAT1/LDHB/AMPKα axis that could be exploited for therapeutic purposes.Subject terms: Cancer models, Non-small-cell lung cancer     

Serum Calcium Response Following Oral Zinc Oxide Administrations in Dairy Cows

Six non-pregnant cows were allocated into 3 groups. Group 1 comprised a pair of lactating cows, whereas groups 2 and 3 each comprised a pair of non-lactating cows. The cows in groups 1 and 2 were dosed intraruminally by stomach tube with zinc oxide at 120 mg Zn per kg of bodyweight at weekly intervals for a period of 33 days. Each cow received a total of 4 doses of zinc oxide. Group 3 served as non-treated control group. Blood samples were collected from all 6 cows daily. Serum was analysed for concentration of calcium. Within 12–24 h of each zinc oxide administration the serum calcium of the lactating cows dropped dramatically indicating the existence of an antagonistic effect between Zn and Ca. The first Zn induced hypocalcaemic episode in the lactating cows was followed by a rise in serum calcium to a level above the pre-dosing level and above the mean value of the control group. The depth of the hypocalcaemic response decreased with the number of zinc oxide dosings. This effect was explained as a response from the stimulation of the calcium homeostatic mechanisms. In the Zn dosed non-lactating cows responses were similar but less clear. The perspective of these findings is discussed in relation to resistance towards parturient hypocalcaemia.     

Antifibrotic role of inducible nitric oxide synthase.

Long-term treatment in rats with l-NAME, an isoform-non-specific inhibitor of nitric oxide synthase (NOS), leads to fibrosis of the heart and kidney, suggesting that nitric oxide (NO) may play a role in preventing tissue fibrosis. In this process, a likely target of NO is the quenching of reactive oxygen species (ROS) through peroxynitrite formation, and one possible source for this NO is inducible NOS (iNOS). Using Peyronie's disease (PD) tissue from both human specimens and from a rat model of PD as the source of fibrotic tissue, we investigated if NO derived from iNOS could act as such an antifibrogenic defense mechanism by determining whether: (a) tunical ROS and iNOS are increased in PD; and (b) the long-term inhibition of iNOS activity decreases the NO/ROS balance in the tunica albuginea thereby promoting collagen deposition. It was determined that in the human PD plaque, iNOS mRNA and protein, ROS, collagen, and the peroxynitrite marker, nitrotyrosine, were all increased in comparison to the normal tunica. In the rat model of PD, the fibrotic plaque also showed significant increases in iNOS mRNA and protein, nitrotyrosine, ROS as measured by heme oxygenase-1, and collagen when compared with the normal control tunica. When a selective inhibitor of iNOS, L-NIL, was given to rats with the PD-like plaque, this resulted in a decrease in nitrotyrosine levels but intensified ROS levels and collagen deposition. These data demonstrate that: (a) iNOS induction occurs in both the human and rat PD fibrotic plaque; and (b) that the NO derived from iNOS appears to counteract ROS formation and collagen deposition. Because the inhibition of iNOS activity leads to a decrease in the NO/ROS ratio, thereby favoring the development of fibrosis, it is proposed that iNOS induction in this tissue may be a protective mechanism against fibrosis and abnormal wound healing.     

Milk Fever Control Principles: A Review

Three main preventive principles against milk fever were evaluated in this literature review, and the efficacy of each principle was estimated from the results of controlled investigations. Oral calcium drenching around calving apparently has a mean efficacy of 50%–60% in terms of milk fever prevention as well as prevention of milk fever relapse after intravenous treatment with calcium solutions. However, some drenches have been shown to cause lesions in the forestomacs. When using the DCAD (dietary cation-anion difference) principle, feeding rations with a negative DCAD (measured as (Na + K) – (Cl + S)) significantly reduce the milk fever incidence. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a mean RR between 0.19 and 0.35 when rations with a negative versus positive DCAD are compared. The main drawback from the DCAD principle is a palatability problem. The principle of feeding rations low in calcium is highly efficient in milk fever prevention provided the calcium intake in the dry period is kept below 20 g per day. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a very low mean RR (between 0 and 0.20) (daily calcium intake below versus above 20 g/d). The main problem in implementing the low-Ca principle is difficulties in formulating rations sufficiently low in calcium when using commonly available feeds. The use of large doses of vitamin D metabolites and analogues for milk fever prevention is controversial. Due to toxicity problems and an almost total lack of recent studies on the subject this principle is not described in detail. A few management related issues were discussed briefly, and the following conclusions were made: It is important to supply the periparturient cow with sufficient magnesium to fulfil its needs, and to prevent the dry cows from being too fat. Available information on the influence of carbohydrate intake, and on the effect of the length of the dry period and prepartum milking, is at present insufficient to include these factors in control programmes.