Systematic Identification of Rhythmic Genes Reveals camk1gb as a New Element in the Circadian Clockwork

A wide variety of biochemical, physiological, and molecular processes are known to have daily rhythms driven by an endogenous circadian clock. While extensive research has greatly improved our understanding of the molecular mechanisms that constitute the circadian clock, the links between this clock and dependent processes have remained elusive. To address this gap in our knowledge, we have used RNA sequencing (RNA–seq) and DNA microarrays to systematically identify clock-controlled genes in the zebrafish pineal gland. In addition to a comprehensive view of the expression pattern of known clock components within this master clock tissue, this approach has revealed novel potential elements of the circadian timing system. We have implicated one rhythmically expressed gene, camk1gb, in connecting the clock with downstream physiology of the pineal gland. Remarkably, knockdown of camk1gb disrupts locomotor activity in the whole larva, even though it is predominantly expressed within the pineal gland. Therefore, it appears that camk1gb plays a role in linking the pineal master clock with the periphery.     

Luteinizing hormone and sexual steroid plasma levels after treatment of European sea bass with sustained-release delivery systems for gonadotropin-releasing hormone analogue

Spermiating male European sea bass Dicentrarchus labrax were treated with gonadotropin-releasing hormone agonists (GnRHa), either a GnRHa injection (IN; 25 μg kg⁻¹ body mass) or one of three types of controlled-release GnRHa-delivery systems: fast release implants (EVAc; 1OO μg kg⁻¹), slow release implants (EVSL; lOO μg kg⁻¹) and slow release microspheres (MC; 50 μg kg⁻¹). Luteinizing hormone (LH) release was highly stimulated by all GnRHa treatments, with elevated plasma levels lasting for 2 days in injected fish (IN) and 2, 4 and 6 weeks in controlled-release-treated fish (EVAc, MC and EVSL, respectively), correlating with a 1, 3, 5 and 5 week period of stimulation of milt production, respectively. Plasma levels of the androgens testosterone (T) and 11-ketotestosterone (11-KT), were not significantly affected by the GnRHa treatments. Plasma T was high at early spermiation and declined sharply near the end of this period. Plasma 11-KT levels declined continuously throughout the experiment. Levels of 17,20 β -dihydroxy-4-pregnen-3-one (17,20 β -P), a proposed maturation-inducing steroid (MIS) in European sea bass, fluctuated around 0.2–1 ng ml⁻¹ and were not greatly affected by the treatments. These results indicated a close correlation between sustained stimulation of LH release, achieved by GnRHa-delivery systems, and long-term enhancement of milt production. They also show an absence of changes in the common sex steroids, associated with elevated LH and enhanced spermiation.     

The substrate specificity of yeast hexokinase: reaction with D-arabinose oxime

By chromatography, electrophoresis, n.m.r. spectroscopy, and spectrophotometric assay, it has been shown that D-arabinose oxime acts as a weak substrate for yeast hexokinase. The enzyme-catalysed phosphorylation of the oxime, which exists as a mixture of E (80%) and Z (20%) acyclic forms in solution at equilibrium, is proposed to proceed via the transient formation of a furanoid species. Weak substrate-activity was also observed with 4-deoxy-D-xylo-hexose, but not with 5-deoxy-D-xylo-hexose. The relation of these and previous results concerning the carbohydrate-substrate specificity of yeast hexokinase in solution to X-ray crystallographic studies is discussed.     

Cyto-histological examination of post-vitellogenesis and final oocyte maturation in captive-reared striped bass

The ovarian development of captive-reared, striped bass Morone saxatilis was examined during a 10-week period encompassing the spawning season. Vitellogenic oocytes in March had a mean diameter of 838 ± 18 μm and did not grow significantly thereafter. Except from one non-hormone-treated fish, all females failed to undergo final oocyte maturation (FOM) and their ovaries became atretic with the onset of high spring temperatures. A clearing fixative was found useful in identifying early stages of atresia, evident by the absence of the germinal vesicle (GV). Final oocyte maturation of fish treated with gonadotropin-releasing hormone agonist (GnRHa) consisted of two phases. Early FOM lasted from 1 to 3 weeks, and was associated with lipid-droplet coalescence, and displacement of the GV and yolk globules to the peripheral cytoplasm. Late FOM lasted <24h, and consisted of yolk-globule coalescence and GV breakdown (GVBD). Ovulated eggs had completely coalesced lipid and yolk masses, with cortical alveoli lined against the cell wall. Both phases of FOM were associated with significant increases in oocyte diameter. Striped bass oocytes showed important morphological differences compared to oocytes of other members of the Moronidae family, in terms of percentage lipid content, chorion thickness and degree of hydration after ovulation.     

Plant-growth regulators derived from the sweetener stevioside

A series of isosteviol derivatives such as aromatic esters and amino acid amides were synthesized. Their effects on seed germination and root elongation of the crop plants, Capsicum annuum, Lens culinaris medicus, Lycopersicon esculentum, Trifollium spp. and Triticum vulgare, were studied. The derivatives could be arranged into four groups: (1) seed germination inhibitors (2) root elongation inhibitors (3) root elongation inducers (4) general inhibitors.     

The living and the dead: How do taphonomic processes modify relative abundance and skeletal completeness of freshwater fish?

This study is designed to determine the extent to which taphonomic processes alter the taxonomic composition of fish remains in lacustrine sediments. We wish to explore information loss in a bone assemblage relative to the original, living community. We examined fish bone assemblages from lacustrine sediments along the southern shore of Lake Kinneret (Sea of Galilee) and compared them to modern living communities. For this purpose we randomly selected 24 squares, each 0.5 m² in size, and excavated them to a depth of 30–50 cm. Three lithofacies were recovered, spanning the past 1500 years (unccorected for reservoir age). The fish remains include 5037 bones and 758 scales, of which 1566 bones were identified to taxonomic group. The list of identified species was compared with the list of indigenous species known to live in Lake Kinneret in general and in a similar sandy habitat in particular. The proportion of skeletal elements found was compared with the proportion known in a complete fish. Our study indicates that differences exist between the three lithofacies in species diversity and composition, skeletal element richness, completeness, and relative abundance. In addition, the bones exhibit a clumped distribution pattern, regardless of depositional depth. From a taphonomic and paleoecological perspective, our findings demonstrate that fish remains retrieved from lacustrine sediments do not represent the composition and diversity of species as in the recent fish community.     

alpha2,6-Sialylation promotes binding of placental protein 14 via its Ca2+-dependent lectin activity: insights into differential effects on CD45RO and CD45RA T cells

Placental protein 14 (PP14; glycodelin) is a pregnancy-associated immunoregulatory protein that is known to inhibit T cells via T-cell receptor desensitization. The recent demonstration of PP14 as lectin has provided insight into how it may mediate its CD45 glycoprotein-dependent T-cell inhibition. In this study, we have investigated PP14's lectin-binding properties in detail. Significantly, PP14 reacts with N-acetyllactosamine (LacNAc) as was also found for members of the galectin family, such as the potent immunoregulatory protein, galectin-1. However, in contrast to galectin-1, PP14's binding is significantly enhanced by alpha2,6-sialylation and also by the presence of cations. This was demonstrated by preferential binding to fetuin as compared with its desialylated variant asialofetuin (ASF) and by using free alpha2,6- versus alpha2,3-sialylated forms of LacNAc in competitive inhibition and direct solid-phase binding assays. Interestingly, from immunological point of view, PP14 also binds differentially to CD45 isoforms known to differ in their degree of sialylation. PP14 preferentially inhibits CD45RA+, as compared with CD45RO+ T cells, and preferentially co-capped this variant CD45 on the T-cell surface. Finally, we demonstrate that PP14 promotes CD45 dimerization and clustering, a phenomenon that may regulate CD45 activity.     

Genetic mapping of a major codominant QTL associated with β-carotene accumulation in watermelon

The common flesh color of commercially grown watermelon is red due to the accumulation of lycopene. However, natural variation in carotenoid composition that exists among heirloom and exotic accessions results in a wide spectrum of flesh colors. We previously identified a unique orange flesh watermelon accession (NY0016) that accumulates mainly β-carotene and no lycopene. We hypothesized this unique accession could serve as a viable source for increasing provitamin A content in watermelon. Here we characterize the mode of inheritance and genetic architecture of this trait. Analysis of testcrosses of NY0016 with yellow and red fruited lines indicated a codominant mode of action as F₁ fruits exhibited a combination of carotenoid profiles from both parents. We combined visual color phenotyping with genotyping-by-sequencing of an F_2:3 population from a cross of NY0016 by a yellow fruited line, to map a major locus on chromosome 1, associated with β-carotene accumulation in watermelon fruit. The QTL interval is approximately 20 cM on the genetic map and 2.4 Mb on the watermelon genome. Trait-linked marker was developed and used for validation of the QTL effect in segregating populations across different genetic backgrounds. This study is a step toward identification of a major gene involved in carotenoid biosynthesis and accumulation in watermelon. The codominant inheritance of β-carotene provides opportunities to develop, through marker-assisted breeding, β-carotene-enriched red watermelon hybrids.