Consequences of inbreeding for the cowpea seed beetle, Callosobruchus maculatus (F.)(Coleoptera: Bruchidae)

Inbreeding is said to reduce vigour and fitness. It may also determine how a population responds to selection. Local populations of Callosobruchus maculatus , the cowpea seed beetle, are established annually from small numbers of founders and the species has been distributed to many parts of the world where isolated populations may have been founded by very small numbers of individuals. After more than 20 generations of inbreeding, inbred lines have been shown to diverge from a common ancestral stock in similar directions with respect of some variables such as developmental speed, but haphazardly in respect of other parameters such as male weight. The respective roles of drift and of selection as effective evolutionary forces in inbred lines are discussed in the light of these results. It is argued that some intraspecific differences in C. maculatus may be explained as a product of periodic inbreeding, but that the process does not impair the ability to adapt to local conditions so contributing to the status of the species as a pest of international importance.     

Pyrrolizidine alkaloid deters ant predators of Utetheisa ornatrix eggs: effects of alkaloid concentration,oxidation state,and prior exposure of ants to alkaloid-laden prey

To examine the chemical defense of lepidopteran eggs towards ant predators, eggs of the arctiid moth Utetheisa ornatrix were offered to laboratory colonies of the ant Leptothorax longispinosus. The ants rapidly devoured Utetheisa eggs produced by parents reared on an alkaloid-free diet, but left eggs that had been endowed with parental alkaloid largely unmolested. That defense can be attributed directly to the presence of a pyrrolizidine alkaloid since topical application of monocrotaline in either its free base or N-oxide state conferred protection on otherwise palatable eggs. The N-oxide and free base were not equally effective in conferring protection however; free-base treated eggs were subject to greater predation than N-oxide treated eggs after 24 h. The emergence of differential alkaloid effectiveness only after prolonged exposure is consistent with the notion that chemical protection is seldom absolute. That difference was resolved only when the otherwise food-deprived ants exceeded a certain threshold of hunger. The efficacy of applied monocrotaline as a predator deterrent increased with increasing concentration of N-oxide, but was lowest for eggs treated with an intermediate concentration of free base. The latter concentration effect likely represents an artefact of the behaviour of the ant colonies offered eggs treated with an intermediate concentration, as those colonies were the most voracious predators in reference tests with palatable eggs. In addition to the immediate deterrent value of pyrrolizidine alkaloid, ant colonies that had been exposed to alkaloid-laden eggs subsequently avoided even palatable, unprotected eggs offered 33 days later. Our data provide the first demonstration of such long-term avoidance of chemically protected lepidopteran prey by an invertebrate. The discovery of a mechanism promoting learned avoidance on the part of ant predators has important ramifications to egg-laying strategies of female Utetheisa, both in terms of the dispersion of eggs, and the extent to which eggs are provisioned with alkaloid.     

The Design and Use of Variance Component Models in the Analysis of Human Quantitative Pedigree Data

The use of variance components and multivariate linear models in genetics applications has a long history that dates back to (at least) Fisher's seminal 1918 paper “The correlation between relatives on the supposition of Mendelian inheritance” [Phil. Trans. 52: 399–433]. Although extensions and elaborations of Fisher's insights have been offered in recent times, relatively few studies exist which examine the theoretical and operational properties variance component models possess in complicated genetic analysis settings. In this paper variance component models, as well as some of their properties (e.g., power, efficiency, and sample size considerations) are discussed in the context of each of the following genetic analysis settings: 1. the detection of general polygenic additive and dominance effects; 2. the detection of genetic effects in the presence of environmental effects (and vice versa); 3. the detection of pleiotropic gene action; 4. aspects of the detection of genotype by environment interaction; and 5. sequential tests for general hypotheses framed in the context of settings 1 through 4. Exposition of the proposed methods and results are facilitated through a special emphasis placed on pedigree covariance structure modeling.     

The role of carboxyl groups on the chitosanase and CMCase activity of a bifunctional enzyme purified from a commercial cellulase with EDC modification

The carboxyl groups of the bifunctional cellulase–chitosanase (CCBE), purified from a commercial cellulase prepared from Trichoderma viride were modified using the water-soluble carbodiimide 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide (EDC). The EDC modified CCBE lost 80–90% of its chitosnase activity and 20% of its carboxylmethyl cellulase (CMCase) activity; meanwhile, its conformation changed slightly, which altered the substrate binding affinity to chitosan, without affecting its binding to CMC. However, the modification did not alter the structure integrity. The dynamic analysis of modification indicated that the CCBE possessed two carboxylates essential for its chitosanase activity and one carboxyl group for its CMCase activity. One of the two carboxylates involved in chitosanase activity was deduced to be the proton donator, and the other may function for substrate recognition, while the only catalytic carboxyl group for CMCase activity probably also acted as a proton donator.     

Genetic Analysis of Line x Tester Progenies Compared in Orthogonally Supplemented Efficiency Balanced Incomplete Block Designs

The theory which analyses the progenies of line X tester crossing procedure and one group of homozygous parents is presented. This analysis allows to conclude on genetics of a quantitative character of parents included in the experiment. The statistics like variance among parents, mean variance of progenies of lines, variance of tester progeny means and covariance of testers with means of their progenies can be derived. On that base one can get four different genetic parameters of variance. In a special case of experiment, it is possible to test the significance of additive variance.     

Versatile signaling mechanisms of inositol pyrophosphates

Inositol pyrophosphates (PP-InsPs) constitute a group of highly charged messengers, which regulate central biological processes in health and disease, such as cellular phosphate and general energy homeostasis. Deciphering the molecular mechanisms underlying PP-InsP-mediated signaling remains a challenge due to the unique properties of these molecules, the different modes of action they can access, and a somewhat limited chemical and analytical toolset. Herein, we summarize the most recent mechanistic insights into PP-InsP signaling, which illustrate our progress in connecting mechanism and function of PP-InsPs.