Does Tribolium brevicornis cuticular chemistry deter cannibalism and predation of pupae?

The cuticular hydrocarbons of insects are species-specific and often function as semiochemicals. The activity of Tribolium brevicornis cuticular hydrocarbons as feeding deterrents that ostensibly function to prevent pupal cannibalism and predation was evaluated. The cuticular hydrocarbons of T. brevicornis pupae were characterized and flour disk bioassays conducted with individual and combined extract components incorporated into artificial diets on which Tribolium adults fed for six days. Feeding by T. brevicornis and T. castaneum on flour disks containing cuticular extracts of T. brevicornis pupae resulted in reduced consumption and weight loss relative to feeding on control flour disks. In both cases, feeding deterrence indices exceeded 80% suggesting that T. brevicornis cuticular hydrocarbons could function to deter cannibalism and predation of pupae by larvae and adult beetles. Sixteen different cuticular hydrocarbons were identified in T. brevicornis pupal extracts. Eight of the commercially available linear alkanes were tested individually in feeding trials with eight Tribolium species. One compound (C28) significantly reduced the amount of food consumed by three species compared to control disks, whereas the compounds C25, C26, and C27 elicited increased feeding in some species. Four other compounds had no effect on consumption for any species. When four hydrocarbon mixtures were tested for synergistic deterrence on T. brevicornis and T. castaneum, none significantly influenced consumption. Our results indicate that the cuticular chemistry of T. brevicornis pupae could serve to deter predation by conspecific and congeneric beetles.

Reduction of animal use with improved procedure for acute tolerance assessment

A retrospective evaluation of previously conducted acute tolerance tests in rats and mice, following oral and intravenous routes of administration, and a review of the literature indicated that a minimum of three animals per group was adequate to characterize acute tolerance. Limited exploratory testing, using six compounds for which classical LD50 tests had been performed previously, indicated that fewer numbers of rats gave comparable results. A method is proposed by which the acute tolerance of a compound may be adequately characterized in both sexes using approximately 30 animals instead of the 70 to 100 used in the classical LD50 test. The objective of the testing procedure is identification of the maximum nonlethal dose or the minimum lethal dose, rather than determination of the LD50.

Conformation-specific antibodies to the alpha chain COOH terminus of hemoglobin A0

An anti-hemoglobin antiserum obtained from a sheep immunized with human carboxyhemoglobin A0 demonstrated little difference in its reactivity with deoxy- or carboxyhemoglobin A0. However, a subpopulation of this antiserum isolated by synthetic peptide affinity chromatography clearly distinguished between these two hemoglobin species. This subpopulation, designated alpha(129-141) anti-hemoglobin antibodies, represents less than 1% of the total anti-hemoglobin antibodies. They are nonprecipitating by Ouchterlony analysis, and fluorescence-quenching studies demonstrate the interaction of a single antibody binding site per hemoglobin dimer. These antibodies bind preferentially to carboxyhemoglobin with a median affinity constant of 5 X 10(8) M-1 compared to binding to deoxyhemoglobin with a binding affinity of less than 1 X 10(8) M-1. Furthermore, the presence of these antibodies in stoichiometric amounts increases the oxygen affinity of hemoglobin, and thus antibody and oxygen binding to hemoglobin can be considered as a linked function.

Stromal Pbrm1 mediates chromatin remodeling necessary for embryo implantation in the mouse uterus

Early gestational loss occurs in approximately 20% of all clinically recognized human pregnancies and is an important cause of morbidity. Either embryonic or maternal defects can cause loss, but a functioning and receptive uterine endometrium is crucial for embryo implantation. We report that the switch/sucrose nonfermentable (SWI/SNF) remodeling complex containing polybromo-1 (PBRM1) and Brahma-related gene 1 (BRG1) is essential for implantation of the embryonic blastocyst on the wall of the uterus in mice. Although preimplantation development is unaffected, conditional ablation of Pbrm1 in uterine stromal cells disrupts progesterone pathways and uterine receptivity. Heart and neural crest derivatives expressed 2 (Hand2) encodes a basic helix-loop-helix (bHLH) transcription factor required for embryo implantation. We identify an enhancer of the Hand2 gene in stromal cells that requires PBRM1 for epigenetic histone modifications/coactivator recruitment and looping with the promoter. In Pbrm1cKO mice, perturbation of chromatin assembly at the promoter and enhancer sites compromises Hand2 transcription, adversely affects fibroblast growth factor signaling pathways, prevents normal stromal-epithelial crosstalk, and disrupts embryo implantation. The mutant female mice are infertile and provide insight into potential causes of early pregnancy loss in humans.

The availability to the rat of energy from various diet ingredients

The digestible and metabolizable energy values of 8 ingredients commonly used in laboratory animal diets were determined using the growing male rat, by the total collection method. Each ingredient was incorporated into a basal diet of maize, wheat, soyabean meal and fishmeal. The metabolizable energy values, on a dry matter basis, corrected to the nitrogen retention of the basal diet for rats per 100 g bodyweight were as follows: maize 15.23 MJ/kg, extracted soyabean meal 14.11 MJ/kg, barley 12.31 MJ/kg, wheat 14.09 MJ/kg, oatfeed 1.36 MJ/kg, white fishmeal 11.61 MJ/kg, dried skimmed milk 14.32 MJ/kg, casein 17.91 MJ/kg. Additional analytical data for the 8 ingredients are also given.

Protein kinase cascades in intracellular signalling by interleukin-I and tumour necrosis factor

Interleukin 1 (IL-1) and tumour necrosis factor (TNF) are major mediators of inflammation, with similar actions. Their receptor mechanisms and downstream pathways are reviewed. They activate several protein kinases in fibroblasts, including the three types of mitogen-activated protein kinase (MAPK), the kinase of the inhibitor of nuclear factor-kappa B (I kappa BK), and the TNF-/IL-1-activated beta-casein kinase. Cultured cells show a broader spectrum of kinase activation by IL-1 than tissues in vivo, suggesting that the receptors connect to more pathways in proliferating cells than in resting differentiated cells. The c-Jun N-terminal kinase (JNK) is strongly activated by IL-1 in tissues. In rabbit liver this is mediated by MAPK kinase 7; the upstream kinase is unidentified. Little is known of downstream MAPK targets in inflammation. Inhibitor experiments suggest that p38MAPK mediates induction of cyclo-oxygenase-2 and metalloproteinases by IL-1, and of TNF, IL-1 and cyclo-oxygenase-2 by endotoxin (in monocytes). p38MAPK is needed for induction of the mRNAs (except IL-1 mRNA).

Science Translational Medicine Podcast: 27 April 2016

Peptide-coated beads could be used for contraception or to select the sperm best suited for use in assisted reproduction.