CASSIOPE: An expert system for conserved regions searches

Background  

Understanding genome evolution provides insight into biological mechanisms. For many years comparative genomics and analysis of conserved chromosomal regions have helped to unravel the mechanisms involved in genome evolution and their implications for the study of biological systems. Detection of conserved regions (descending from a common ancestor) not only helps clarify genome evolution but also makes it possible to identify quantitative trait loci (QTLs) and investigate gene function.     

Conceptual framework and rationale

The sterile insect technique (SIT) has been shown to be an effective and sustainable genetic approach to control populations of selected major pest insects, when part of area-wide integrated pest management (AW-IPM) programmes. The technique introduces genetic sterility in females of the target population in the field following their mating with released sterile males. This process results in population reduction or elimination via embryo lethality caused by dominant lethal mutations induced in sperm of the released males. In the past, several field trials have been carried out for mosquitoes with varying degrees of success. New technology and experience gained with other species of insect pests has encouraged a reassessment of the use of the sterility principle as part of integrated control of malaria vectors. Significant technical and logistic hurdles will need to be overcome to develop the technology and make it effective to suppress selected vector populations, and its application will probably be limited to specific ecological situations. Using sterile males to control mosquito vector populations can only be effective as part of an AW-IPM programme. The area-wide concept entails the targeting of the total mosquito population within a defined area. It requires, therefore, a thorough understanding of the target pest population biology especially as regards mating behaviour, population dynamics, dispersal and level of reproductive isolation. The key challenges for success are: 1) devising methods to monitor vector populations and measuring competitiveness of sterile males in the field, 2) designing mass rearing, sterilization and release strategies that maintain competitiveness of the sterile male mosquitoes, 3) developing methods to separate sexes in order to release only male mosquitoes and 4) adapting suppression measures and release rates to take into account the high reproductive rate of mosquitoes. Finally, success in area-wide implementation in the field can only be achieved if close attention is paid to political, socio-economic and environmental sensitivities and an efficient management organization is established taking into account the interests of all potential stakeholders of an AW-IPM programme.     

Dimerization of Receptor Protein-Tyrosine Phosphatase alpha in living cells

Background  

Dimerization is an important regulatory mechanism of single membrane-spanning receptors. For instance, activation of receptor protein-tyrosine kinases (RPTKs) involves dimerization. Structural, functional and biochemical studies suggested that the enzymatic counterparts of RPTKs, the receptor protein-tyrosine phosphatases (RPTPs), are inhibited by dimerization, but whether RPTPs actually dimerize in living cells remained to be determined.     

Adverse environmental conditions influence age-related innate immune responsiveness

Hutchinson-Gilford progeria syndrome (HGPS) is a rare premature aging disorder that belongs to a group of conditions called laminopathies which affect nuclear lamins. Mutations in two genes, LMNA and ZMPSTE24, have been found in patients with HGPS. The p.G608G LMNA mutation is the most commonly reported mutation. The aim of this work was to compile a comprehensive literature review of the clinical features and genetic mutations and mechanisms of this syndrome as a contribution to health care workers. This review shows the necessity of a more detailed clinical identification of Hutchinson-Gilford progeria syndrome and the need for more studies on the pharmacologic and pharmacogenomic approach to this syndrome.     

Changes in the electrical polarity of tobacco cells following the application of weak external currents

Weak externally applied electric currents changed the natural electrical pattern surrounding cells from tobacco (Nicotiana tabacum L.) suspension cultures. The artificial currents were applied transversely to short filaments of cells placed between a microelectrode lose to the filament surface and a large platinum electrode some distance away. The natural current patterns before and after electrical treatment were measured with a vibrating probe. Significant effects were confined to the cell adjacent to the microelectrode. Currents with densities of 100 A · cm^–2 at the cell surface applied for 10 min or 3 A · cm^–2 for several hours caused a localized increase in the natural current entering the part of the cell which had been nearest the positive electrode. There was no corresponding local increase in current leaving from the opposite side of the cell. Instead, the extra current appeared to leave over a relatively large area. The overall effect was a tendency for the cell to repolarize transversely with a greater proportion of its transcellular currents flowing in the direction of the current applied. The effect was measurable for several hours after the external current was discontinued and may be evidence for a natural mechanism by which neighbouring cells entrain one another's polarities during differentiation. The effect of external currents on cells growing in a 2,4-dichlorophenoxyacetic acid (2,4-D) medium (which suppresses differentiation) was qualitatively the same as on cells in an indole-3-acetic acid medium (which promotes differentiation). If anything, the response was greater in 2,4-D, implying that the disruptive effect of 2,4-D on cell and tissue polarization is not a consequence of it preventing cells sensing the transcellular currents of their neighbours.Abbreviation 2,4-D 2,4-dichlorophenoxyacetic acid The authors are indebted to the Agricultural and Food Research Council of the U.K. for financial support and to the Royal Society for the provision of the vibrating probe.     

Aquaculture of sponges on scallops for natural products research and antifouling

Suspended culture of scallops (Pectinidae: Bivalvia) is plagued by invertebrate fouling. Scallops covered in an orange sponge (Suberites ficus ssp. rubrus), however, do not have any other invertebrates fouling their shells and the sponge is easily removed. Sponges may also be valuable sources of bioactive compounds. Seven species of sponge were found to be associated with Chlamys opercularis but none were found associated with Pecten maximus. Standing crop of sponge on the scallop farm was just over one tonne. If all the scallops were covered by sponge this would rise to approximately 4.5 tonnes (from three million scallops). Primary cell cultures of (S.f. rubrus) were successfully established but no cell lines were achieved. A number of techniques were tried for establishing cells and pieces of sponge tissue onto scallop shells but none gave satisfactory results. Likewise mechanical methods for sticking small pieces of sponge to scallop shells were deemed impractical even where they resulted in subsequent sponge growth. Improving natural settlement of sponges onto the scallops was the only economically practical method for increasing sponge yield for C. opercularis, though other methods would need to be devised for P. maximus.     

Potencies of naturally-occurring AKH/RPCH peptides in Locusta migratoria in the acetate uptake assay in vitro and comparison with their potencies in the lipid mobilisation assay in vivo

The biological potencies of a number of naturally-occurring octa- and decapeptides of the large AKH/RPCH family of peptides were determined in Locusta migratoria using the lipid-mobilising assay in vivo and the acetate uptake assay in vitro. The most potent of the newly-tested peptides in the in vitro assay, Phl-CC, differs from the endogenous major locust peptide, Lom-AKH-I, only by an exchange of serine versus threonine at position 10. However, the most active peptide in the in vitro assay remains Lom-AKH-III. At the other extreme is the peptide Mem-CC which contains a tyrosine residue at position 4 rather than the more typical phenylalanine. This peptide is over 20,000 times less potent than Lom-AKH-III in the in vitro assay, and also results in an unusual dose-response curve in the in vivo assay. Only a few peptides are approximately equipotent in both assays, but mostly the bioanalogues have a higher potency in vitro. The majority of them are 2- to 10-fold more potent in vitro, but Ani-AKH and Lom-AKH-III are 19- and 48-fold more potent. The results are discussed in relation to either the actions of proteases or of possible preferential binding of different receptors involved in the different assays.     

Identification of four CCCH zinc finger proteins in Xenopus, including a novel vertebrate protein with four zinc fingers and severely restricted expression

Tristetraprolin (TTP), the prototype of a class of CCCH zinc finger proteins, is a phosphoprotein that is rapidly and transiently induced by growth factors and serum in fibroblasts. Recent evidence suggests that a physiological function of TTP is to inhibit tumor necrosis factor alpha secretion from macrophages by binding to and destabilizing its mRNA (Carballo, E., Lai, W.S., Blackshear, P.J., 1998. Science, 281, 1001-1005). To investigate possible functions of CCCH proteins in early development of Xenopus, we isolated four Xenopus cDNAs encoding members of this class. Based on 49% overall amino acid identity and 84% amino acid identity within the double zinc finger domain, one of the Xenopus proteins (XC3H-1) appears to be the homologue of TTP. By similar analyses, XC3H-2 and XC3H-3 are homologues of ERF-1 (cMG1, TIS11B) and ERF-2 (TIS11D). A fourth protein, XC3H-4, is a previously unidentified member of the CCCH class of vertebrate zinc finger proteins; it contains four Cx8Cx5Cx3H repeats, two of which are YKTEL Cx8Cx5Cx3H repeats that are closely related to sequences found in the other CCCH proteins. Whereas XC3H-1, XC3H-2, and XC3H-3 were widely expressed in adult tissues, XC3H-4 mRNA was not detected in any of the adult tissues studied except for the ovary. Its expression appeared to be limited to the ovary, oocyte, egg and the early embryonic stages leading up to the mid-blastula transition. Its mRNA was highly expressed in oocytes of all ages, and was enriched in the animal pole cytosol of mature oocytes. Maternal expression was also seen with the other three messages, suggesting the possibility that these proteins are involved in regulating mRNA stability in oocyte maturation and/or early embryogenesis.