Identification of bikunin as an endogenous inhibitor of dynorphin convertase in human cerebrospinal fluid

Dynorphin-converting enzymes constitute a group of peptidases capable of converting dynorphins to enkephalins. Through the action of these enzymes, the dynorphin-related peptides bind to delta-opioid instead of kappa-opioid receptors, leading to a change in the biological function of the neuropeptides. In this article, we describe the identification of the protein bikunin as an endogenous, competitive inhibitor of a dynorphin-converting enzyme in human cerebrospinal fluid. This protein is present together with its target enzyme in the same body fluids. The K(M) value of the convertase was found to be 9 microm, and the K(i) value of the inhibitor was 1.7 nm. The finding indicates that bikunin may play a significant role as a regulatory mechanism of neuropeptides, where one bioactive peptide is converted to a shorter sequence, which in turn, can affect the action of its longer form.     

Detection of endocrine disrupters: evaluation of a Fish Sexual Development Test (FSDT)

Managed by the Organisation for Economic Co-operation and Development (OECD), a comprehensive work is carried out in numerous laboratories to develop test guidelines for the detection of endocrine disrupting chemicals in humans, and various animal species. Development of tests to detect chemicals with endocrine disrupting properties in fish is a part of that work. A Fish Sexual Development Test (FSDT) (an extension of the existing OECD TG 210, fish early life stage toxicity test), proposed as an international test guideline for the detection of endocrine disrupting chemicals, was evaluated by water exposure of juvenile zebrafish to the three natural estrogens: estrone, 17beta-estradiol, and estriol and the synthetic androgen trenbolone (trenbolone acetate). As endpoints, vitellogenin induction and histological changes including changes in sex ratios were investigated. The sex ratio was significantly altered towards females from 49 ng/l estrone, 54 ng/l 17beta-estradiol and 22 microg/l estriol, respectively. An all male population was observed from exposure to 9.7 ng/l trenbolone and above. Significant vitellogenin induction in whole body homogenate was measured after exposure to 14 ng/l estrone, 54 ng/l 17beta-estradiol and 0.6 mug/l estriol, respectively. Significant vitellogenin reduction was measured after exposure to 193 ng/l trenbolone or higher. The present results provide strong evidence that the FSDT is a sensitive test toward estrogenic and especially androgenic exposure and the validation of the FSDT as an OECD test guideline should continue.     

Determination of beta-amyloid peptide signatures in cerebrospinal fluid using immunoprecipitation-mass spectrometry

Early pathogenic events in Alzheimer's disease (AD) involve increased production and/or reduced clearance of beta-amyloid (Abeta), especially the 42 amino acid fragment Abeta1-42. The Abeta1-42 peptide is generated through cleavage of the amyloid precursor protein by beta- and gamma-secretase and is catabolised by a variety of proteolytic enzymes such as insulin-degrading enzyme and neprilysin. Here, we describe a method that employs immunoprecipitation combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to determine the pattern of C-terminally truncated Abeta peptides in cerebrospinal fluid (CSF). Using antibodies coupled to magnetic beads, we have detected 18 C-terminally and 2 N-terminally truncated Abeta peptides in CSF. By determining the identity and profile of the truncated Abeta peptides, more insight may be gained about differences in the metabolism and structural properties of Abeta in AD. Finally, the Abeta fragment signatures may prove useful as a diagnostic test for AD.     

Identification of the major spliceosomal RNAs in Dictyostelium discoideum reveals developmentally regulated U2 variants and polyadenylated snRNAs

Most eukaryotic mRNAs depend upon precise removal of introns by the spliceosome, a complex of RNAs and proteins. Splicing of pre-mRNA is known to take place in Dictyostelium discoideum, and we previously isolated the U2 spliceosomal RNA experimentally. In this study, we identified the remaining major spliceosomal RNAs in Dictyostelium by a bioinformatical approach. Expression was verified from 17 small nuclear RNA (snRNA) genes. All these genes are preceded by a putative noncoding RNA gene promoter. Immunoprecipitation showed that snRNAs U1, U2, U4, and U5, but not U6, carry the conserved trimethylated 5' cap structure. A number of divergent U2 species are expressed in Dictyostelium. These RNAs carry the U2 RNA hallmark sequence and structure motifs but have an additional predicted stem-loop structure at the 5' end. Surprisingly, and in contrast to the other spliceosomal RNAs in this study, the new U2 variants were enriched in the cytoplasm and were developmentally regulated. Furthermore, all of the snRNAs could also be detected as polyadenylated species, and polyadenylated U1 RNA was demonstrated to be located in the cytoplasm.     

Embryonic gonadal and sexual organ development in a small viviparous skink, Niveoscincus ocellatus

The majority of research into the timing of gonad differentiation (and sex determination) in reptiles has focused on oviparous species. This is largely because: (1) most reptiles are oviparous; (2) it is easier to manipulate embryonic developmental conditions (e.g., temperature) of eggs than oviductal embryos and (3) modes of sex determination in oviparous taxa were thought to be more diverse since viviparity and environmental sex determination (ESD)/temperature-dependent sex determination (TSD) were considered incompatible. However, recent evidence suggests the two may well be compatible biological attributes, opening potential new lines of enquiry into the evolution and maintenance of sex determination. Unfortunately, the baseline information on embryonic development in viviparous species is lacking and information on gonad differentiation and sexual organ development is almost non-existent. Here we present an embryonic morphological development table (10 stages), the sequence of gonad differentiation and sexual organ development for the viviparous spotted snow skink (Niveoscincus ocellatus). Gonad differentiation in this species is similar to other reptilian species. Initially, the gonads are indifferent and both male and female accessory ducts are present. During stage 2, in the middle third of development, differentiation begins as the inner medulla regresses and the cortex thickens signaling ovary development, while the opposite occurs in testis formation. At this point, the Müllerian (female reproductive) duct regresses in males until it is lost (stage 6), while females retain both ducts until after birth. In the later stages of testis development, interstitial tissue forms in the medulla corresponding to maximum development of the hemipenes in males and the corresponding regression in the females.     

Spikelet structure and development in Cyperoideae (Cyperaceae): a monopodial general model based on ontogenetic evidence

Background and Aims

In Cyperoideae, one of the two subfamilies in Cyperaceae, unresolved homology questions about spikelets remained. This was particularly the case in taxa with distichously organized spikelets and in Cariceae, a tribe with complex compound inflorescences comprising male (co)florescences and deciduous female single-flowered lateral spikelets. Using ontogenetic techniques, a wide range of taxa were investigated, including some controversial ones, in order to find morphological arguments to understand the nature of the spikelet in Cyperoideae. This paper presents a review of both new ontogenetic data and current knowledge, discussing a cyperoid, general, monopodial spikelet model.

Methods

Scanning electron microscopy and light microscopy were used to examine spikelets of 106 species from 33 cyperoid genera.

Results

Ontogenetic data presented allow a consistent cyperoid spikelet model to be defined. Scanning and light microscopic images in controversial taxa such as Schoenus nigricans, Cariceae and Cypereae are interpreted accordingly.

Conclusions

Spikelets in all species studied consist of an indeterminate rachilla, and one to many spirally to distichously arranged glumes, each subtending a flower or empty. Lateral spikelets are subtended by a bract and have a spikelet prophyll. In distichously organized spikelets, combined concaulescence of the flowers and epicaulescence (a newly defined metatopic displacement) of the glumes has caused interpretational controversy in the past. In Cariceae, the male (co)florescences are terminal spikelets. Female single-flowered spikelets are positioned proximally on the rachis. To explain both this and the secondary spikelets in some Cypereae, the existence of an ontogenetic switch determining the development of a primordium into flower, or lateral axis is postulated.     

Regulation of tillering in sorghum: genotypic effects

MethodsFive sorghum hybrids, derived from inbred lines with a common genetic background and with similar phenology and plant height but contrasting tillering, were grown in five experiments. The experiments covered a wide range in radiation and temperature conditions, so that number of tillers produced varied significantly. Data on leaf area, tiller number, and biomass accumulation and partitioning were collected at regular intervals. To quantify internal plant competition for carbohydrates, a carbohydrate supply–demand index (S/D_index) was developed and related to variation in tillering.ConclusionsThe results support the hypothesis that genotypic differences in tillering were associated with differences in plant carbon S/D balance, associated with differences in leaf size and in the threshold at which tillers grow out. The results provide avenues for phenotyping of mapping populations to identify genomic regions regulating tillering. Incorporating the results in crop growth simulation models could provide insight into the complex genotype-by-management-by-environment interactions associated with drought adaptation.