Homeotic gene function in the muscles of Drosophila larvae

The segmental musculature of Drosophila melanogaster larvae consists of 24-30 muscles per segment. Unique patterns of muscles are found in the three thoracic segments and the first and last abdominal segments; the remaining abdominal segments share the same pattern. Mutations in Ultrabithorax (Ubx) cause partial transformation of the muscle pattern of larval abdominal segments towards metathorax. The muscles of the thorax are not affected. In the first two abdominal segments the changes include the loss of at least 11 `abdominal' muscles and the gain of 11 `thoracic' muscles. Less extensive transformations are seen in more posterior abdominal segments. Anterobithorax, bithorax, postbithorax and bithoraxoid mutations also induce transformations of the larval musculature. Each allelic group affects a domain that is a subset of the entire Ubx domain but these domains are not restricted to compartments or segments and may extend through as many as five segments. In the muscles the segmental distribution of Ubx antigen correlates with the segments affected by Ubx mutations. The different domains of Ubx in mesoderm and ectoderm argue that the segmental diversity of the muscle pattern is not simply induced by the overlying epidermis and that Ubx function in the mesoderm is required for the correct development of abdominal segments.     

Early ontogeny of Adinia xenica (Pisces,Cyprinodontiformes): 3. Comparison and evolutionary significance of some patterns in epigenesis of egg-scattering,hiding and bearing cyprinodontiforms

Synopsis Developmental patterns as seen in cyprinodontiforms fishes with different reproductive styles are compared, and discussed in relation to ecology and evolutionary significance. The discussion centres around Adinia xenica (its detailed ontogeny presented in two previous sequels to this paper), and, from the existing literature, Fundulus heteroclitus (closely related), Austrofundulus myersi (an annual) and Platypoecilus maculatus (a livebearer). The embryonic resting interval is present in various forms in the first three species, and differences in it and the overall patterns of development are shown to be consistent with ecological conditions. Termination of the resting interval leads immediately to hatching, a process in A. xenica, as in F. heteroclitus, apparently initiated by the appropriate summation of internal and external factors. These factors include any or all of: metabolic changes and increased oxygen requirements, response to light, reduced environmental oxygen, agitation, and increased hydrostatic pressure. They all can cause increased movement by the embryo which is credited with rupturing hatching gland cells and releasing the enzyme(s). Annual fishes experience 3 pronounced resting intervals, termed diapauses. These are discussed in the context of apparent steps and thresholds, and evolutionary ecology. A possible evolutionary sequence, from a simple fractional spawning pattern to diapause, is presented. Morphological differences in primary embryonic respiratory surfaces, as seen in the four species, are related to environmental conditions. The above illustrate ways in which the same basic structures and events are modified to cope with different habitats.     

Family and Community in Ireland.

Family and Community in Ireland. Conrad M. Arensberg and Solon T. Kimball. Third edition, with. new introduction by Anne Byrne, Ricca Edmondson, and Tony Varley. Ennis, Ireland: Clasp Press, 2001. 417 pp.     

Neuroanatomical distribution of aromatase mRNA in the rat brain: indications of regional regulation

Aromatase, the enzyme responsible for the conversion of testosterone to estradiol, is found in the rat brain and is present in regions of the preoptic area, hypothalamus, and limbic system. Gonadal steroid hormones regulate aromatase activity levels in many brain regions, but not all. Using in situ hybridization, we examined the distribution of aromatase mRNA in the adult male forebrain, as well as the levels of aromatase mRNA in the brains of males and females, and the regulation by gonadal steroid hormones. In the adult male, many heavily labelled cells were found in the encapsulated bed nucleus of the stria terminalis (BNST), the medial preoptic nucleus (MPN), the ventro-medial nucleus (VMN), the medial amygdala (mAMY) and the cortical amygdala (CoAMY). The regional distribution of aromatase mRNA was similar in males and females, but males tended to have a greater number of aromatase mRNA-expressing cells in each region compared to females. Aromatase mRNA levels in the BNST, MPN, VMN and mAMY tended to be lower in castrated males than in intact males, whereas aromatase mRNA levels were unaltered by castration in the CoAMY. Further analysis of individual cells expressing aromatase mRNA suggests that aromatase mRNA may be regulated by steroid hormones differentially in specific populations of cells in regions where enzyme activity levels are steroid-hormone-dependent.     

Developmental changes in the activity and cellular localization of hepatic casein kinase II in the rat

Abstract The activity and cellular localization of hepatic casein kinase II(CKII) was examined during late fetal development in the rat. Cultured fetal hepatocytes displayed constitutive CKII activity which was not further activated by growth factor exposure. Similarly, fetal liver CKII showed approximately fivefold greater activity than adult liver. The fetal hepatic activity was, to a large degree, localized to a nuclear fraction. Postnuclear cytosol preparations from fetal and adult liver showed similar CKII activity. In all cases, FPLC ion exchange chromatography followed by Western immunoblotting showed that immunoreactive CKII coincided with kinase activity. However, Parallel determinations of CKII activity and immunoreactive CKII levels showed a higher(five-to sixfold) CKII specific activity in nuclear extracts compared to cytosol. In summary, fetal hepatic CKII demonstrates coincident nuclear localization and activation. We hypothesize that the regulation of hepatic CKII is relevant to the mitogen-independent proliferation displayed by fetal rat hepatocytes. © Wiley-Liss, Inc.     

Reactions of 4β,5-epoxy-5β-androstan-3-ones with hydrogen fluoride in pyridine

4β,5-Epoxy-5β-androstane-3,17-dione ($\text{1a}$), 17β-hydroxy-4β,5-epoxy-5β-androstan-3-one ($\text{1b}$) and 17β-acetoxy-4β,5-epoxy-5β-androstan-3-one ($\text{1c}$) were treated with anhydrous hydrogen fluoride in pyridine (70% solution) at 55° and yielded the corresponding 4-en-4-ols e.g. 4-hydroxy-4-androstene-3, 17-dione ($\text{2a}$).As the reaction temperature was lowered each epoxide formed a second product which, at ?75°, was the major component of the reaction mixture and was identified as the 5α-fluoro-4α-ol derivative of the parent enone, e.g. 4α-hydroxy-5-fluoro-5α-androstane-3,17-dione ($\text{3a}$). These fluorohydrins are thermally unstable, losing hydrogen fluoride.The acetates of the fluorohydrins were also prepared, characterized, and shown to be more stable than the parent alcohols.