Purification and kinetic characterisation of juvenile hormone esterase from Drosophila melanogaster

Juvenile hormone esterase (JHE) from the prepupal stage of Drosophila melanogaster was purified about 429-fold to near homogeneity by selective precipitations, isoelectric focussing, anion exchange and gel filtration chromatography. The KM and Vmax of the purified enzyme for juvenile hormone III (JHIII) hydrolysis are 89 nM and at least 590 nmol/min/mg, respectively. JHE also hydrolyses the artificial substrate alpha-naphthyl acetate with a KM of 120 micro M and a Vmax of at least 70 mumol/min/mg. Competition of JHIII hydrolysis by five juvenile hormones and twenty-four JH analogues showed JHE is highly selective for JHIII and JHIII bisepoxide (JHP3), and both may be in vivo substrates. Binding in the active site of JHE is promoted by structural features found in JHIII and JHB3 including the epoxide groups in their natural orientations, methyl (rather than ethyl) side-chains, and the 2E, 3 double bond that is conjugated with the ester group. Binding is reduced by almost any departure from these structural features of JH. Co-incubation of the haemolymph JH binding protein, lipophorin, with JHE indicates lipophorin might modulate JH hydrolysis by competition for binding of JH.     

A genetic analysis of aromatic amino acid hydroxylases involvement in DOPA synthesis during Drosophila adult development

This study was designed to examine whether cyclosporine (CyA) acts on the endocrine system by modifying the pulsatile secretion pattern of prolactin and LH. Both pituitary-grafted and sham-operated rats were submitted to a subcutaneous vehicle or CyA (5 mg/kg) treatment daily for 10 days beginning on the day of surgery. Pituitary grafting and/or CyA administration changed the pulsatile pattern of prolactin observed in sham-operated animals. The mean values of serum prolactin were significantly increased by pituitary grafting and the treatment with CyA further increased them. The mean half-life of prolactin was significantly increased in pituitary-grafted rats and was not changed by CyA administration, although it was decreased in sham-operated rats. The frequency of prolactin pulses was significantly decreased in pituitary-grafted as compared to sham-operated controls and was not further modified by CyA administration. However, in sham-operated rats a significant decrease of this parameter was observed. Duration of the prolactin peaks was significantly increased by pituitary grafting, and was not modified by CyA administration in any of the groups studied. The absolute amplitude of the prolactin peaks was significantly increased in pituitary-grafted as compared to sham-operated animals, and the treatment with CyA further increased this parameter in both groups. Mean values of LH were significantly increased in pituitary-grafted as compared to control rats. CyA administration significantly increased LH levels in sham-operated rats and decreased them in pituitary-grafted animals. The mean half-life, the pulse frequency and the duration of LH peaks were not modified by either pituitary grafting or CyA administration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Genetic analysis of Drosophila larval optic nerve development

To identify genes necessary for establishing connections in the Drosophila sensory nervous system, we designed a screen for mutations affecting development of the larval visual system. The larval visual system has a simple and stereotypic morphology, can be recognized histologically by a variety of techniques, and is unnecessary for viability. Therefore, it provides an opportunity to identify genes involved in all stages of development of a simple, specific neuronal connection. By direct observation of the larval visual system in mutant embryos, we identified 24 mutations affecting its development; 13 of these are larval visual system-specific. These 13 mutations can be grouped phenotypically into five classes based on their effects on location, path or morphology of the larval visual system nerves and organs. These mutants and phenotypic classifications provide a context for further analysis of neuronal development, pathfinding and target recognition.     

Muscle development is independent of innervation during Drosophila embryogenesis

We have examined the role of innervation in directing embryonic myogenesis, using a mutant (prospero), which delays the pioneering of peripheral motor nerves of the Drosophila embryo. In the absence of motor nerves, myoblasts fuse normally to form syncytial myotubes, myotubes form normal attachments to the epidermis, and a larval musculature comparable to the wild-type pattern is generated and maintained. Likewise, the twist-expressing myoblasts that prefigure the adult musculature segregate normally in the absence of motor nerves, migrate to their final embryonic positions and continue to express twist until the end of embryonic development. In the absence of motor nerves, myotubes uncouple at the correct developmental stage to form single cells. Subsequently, uninnervated myotubes develop the mature electrical and contractile properties of larval muscles with a time course indistinguishable from normally innervated myotubes. We conclude that innervation plays no role in the patterning, morphogenesis, maintenance or physiological development of the somatic muscles in the Drosophila embryo.     

Effects of iodine and thyroid hormone deficiency during brain development on activities of cholinergic neurone-related enzymes in central nervous system of rats

To study the effects of iodine and thyroid hormone deficiency during brain development on activities of enzymes of central acetyl choline metabolism, activities of choline acetylcholinetransferase (CHAT) and acetylcholinesterase (AChE) in hippocampus and cerebral cortex, basal forebrain and cerebellum in 20-day-old rats were determined. Results showed that CHAT and AChE activities in hippocampus, cerebral cortex and basal forebrain in iodine deficiency and hypothyroid rats were significantly lower than those in controls. A ratio of membranebound AChE to soluble AChE, activities of inextractable AChE, and percentage of its activities in the four sections of the brain in the trial rats were significantly lower, and activities of soluble AChE and its percentage of activities were significantly higher than those in controls. It suggests iodine and thyroid hormone deficiency could affect maturation of CHAT and disturb transformation and maturation of various molecular types of AChE and delay distinctly the development of cholinergic neurone during the critical period of brain development in rats.     

A role of Ultrabithorax in morphological differences between Drosophila species

The mechanisms underlying the evolution of morphology are poorly understood. Distantly related taxa sometimes exhibit correlations between morphological differences and patterns of gene expression, but such comparisons cannot establish how mechanisms evolve to generate diverse morphologies. Answers to these questions require resolution of the nature of developmental evolution within and between closely related species. Here I show how the detailed regulation of the Hox gene Ultrabithorax patterns trichomes on the posterior femur of the second leg in Drosophila melanogaster, and that evolution of Ultrabithorax has contributed to divergence of this feature among closely related species. The cis-regulatory regions of Ultrabithorax, and not the protein itself, appear to have evolved. This study provides experimental evidence that cis-regulatory evolution is one way in which conserved proteins have promoted morphological diversity.     

A functional analysis of Notch mutations in Drosophila

In 1900, the world population was less than 1.7 billion people; the United Nations projects that in 2000 it will be 6.2, and in 2020, 7.9 billion. The proportion of the elderly (65 years and over), will increase from 5.1% (1950) to 6.8% by the year 2000 and to 8.8% by 2020, when out of an elderly population of 796 million people, 124 million are projected to be 80 years and over. Due to an increasing gender inequality in life expectation, the majority of the elderly will be women. An aged population is a basically new feature in the history of humanity, the implications of which are-as yet-incompletely understood. It is clear, however, that the last years of life are accompanied by an increase in disability and sickness, with very high demands for health and social services. Hence, the soaring elderly population will raise major social, economic and ethical issues worldwide and may strain to the limit the ability of health, social and economic infrastructures of many countries. It may also result in an increasingly large proportion of humanity (the elderly in general and elderly women, in particular) living in absolute poverty. The demographic, health, socioeconomic and ethical dimensions of the problem are discussed with particular emphasis on the situation of elderly women and a plea is made for greatly increased medical and socioeconomic research.     

In situ activation pattern of Drosophila EGF receptor pathway during development

Signaling cascades triggered by receptor tyrosine kinases (RTKs) participate in diverse developmental processes. The active state of these signaling pathways was monitored by examination of the in situ distribution of the active, dual phosphorylated form of mitogen-activated protein kinase (ERK) with a specific monoclonal antibody. Detection of the active state of the Drosophila epidermal growth factor receptor (DER) pathway allowed the visualization of gradients and boundaries of receptor activation, assessment of the distribution of activating ligands, and analysis of interplay with the inhibitory ligand Argos. This in situ approach can be used to monitor other receptor-triggered pathways in a wide range of organisms.     

Genetic analysis of heat shock response in three Drosophila species of the obscura group

Heat shock response was investigated in three species of the obscura group of the Drosophila genus (D. subobscura, D. guanche, and D. madeirensis) by chromosome cytology analysis and [3H]uridine labeling. A set of eight puffs (2C, 15DE, 18C, 27A, 31CD, 85AB, 89A, and 94A) were induced after heat treatments in each of the three species; 18C, 27A, 89A, and 94A were the most heavily labeled in the autoradiograms after the induced conditions. From the in situ results using the major heat shock genes of D. melanogaster as a probe, it was inferred that the 18C, 94A, 89A, and 27A loci of the three obscura group species are homologous to D. melanogaster loci, which contain, HSP82, HSP70, HSP68, and HSPs encoding for the small heat shock proteins, respectively. When this organization was compared with that of D. melanogaster, fewer evolutionary changes, mainly gene duplications, were found to have occurred in the obscura group species than in the D. melanogaster group. In the three species analyzed in this work, as well as in the other Drosophila species studied, the heat shock genes are distributed on D and E Muller's elements, behaving as single copy genes that do not move around the genome.     

Common and distinct roles of DFos and DJun during Drosophila development

The Drosophila homolog of c-Jun regulates epithelial cell shape changes during the process of dorsal closure in mid-embryogenesis. Here, mutations in the DFos gene are described. In dorsal closure, DFos cooperates with DJun by regulating the expression of dpp; Dpp acts as a relay signal that triggers cell shape changes and DFos expression in neighboring cells. In addition to the joint requirement of DFos and DJun during dorsal closure, DFos functions independently of DJun during early stages of embryogenesis. These findings demonstrate common and distinct roles of DFos and DJun during embryogenesis and suggest a conserved link between AP-1 (activating protein-1) and TGF-beta (transforming growth factor-beta) signaling during epithelial cell shape changes.     

Changes in gene expression during post-eclosional development in the olfactory system of Drosophila melanogaster

We have found that the expression of some genes in Drosophila melanogaster changes during the life of the adult fly. These changes can be illustrated by the use of enhancer trap lines which mark the expression of particular genes in the adult fly. Although the fly is considered able to perform most necessary adult functions within the first 72 h after eclosion from the pupal case, we find changes in expression over the first 10 days of life in the antennae of several of the genes we have examined. Some genes change by increasing from an initially low level of expression of the marked gene, while other lines, which we have termed 'late-onset' genes, show no expression of the marked gene until 4-5 days following eclosion. In contrast, some genes decrease their expression during the first 10 days of life. The changes in gene expression seen over the first 10 days of the fly's adult life provides molecular evidence of the many maturational changes occurring during the early life of the adult fly.     

Gene expression of trehalase during post-dormant development of the brine shrimp, Artemia: comparison of the two species

The purpose of this article is to summarize the short-term and long-term results of the authors' clinical prospective study on the treatment of Class III malocclusion using the protraction facemask. An attempt is made to answer questions pertaining to this treatment modality. Twenty patients with skeletal Class III malocclusion were treated consecutively with maxillary expansion and a protraction facemask. A positive overjet was obtained in all cases after 6 to 9 months of treatment. These changes were contributed to by a forward movement of the maxilla, backward and downward rotation of the mandible, proclination of the maxillary incisors, and retroclination of the mandibular incisors. The molar relationship was overcorrected to Class I or Class II dental arch relationship. The overbite was reduced with a significant increase in lower facial height. The treatment was found to be stable 2 years after removal of the appliances. At the end of the 4-year observation period, 15 of the 20 patients maintained a positive overjet or an end-to-end incisal relationship. Patients who reverted back to a negative overjet were found to have excess horizontal mandibular growth that was not compensated by proclination of the maxillary incisors. A review of the literature showed that maxillary expansion in conjunction with protraction produced greater forward movement of the maxilla. Maxillary protraction with a 30 degrees forward and downward force applied at the canine region produced an acceptable clinical response. The reciprocal force from maxillary protraction transmitted to the temporomandibular joint did not increase masticatory muscle pain or activity. Significant soft tissue profile change can be expected with maxillary protraction including straightening of the facial profile and better lip competence and posture. However, one should anticipate individual variations in treatment response and subsequent growth changes. Treatment with the protraction facemask is most effective in Class III patients with a retrusive maxilla and a hypodivergent growth pattern. Treatment initiated at the time of initial eruption of the upper central incisors helps to maintain the anterior occlusion after treatment.     

A microsatellite-based multilocus phylogeny of the Drosophila melanogaster species complex

Uncovering the genealogy of closely related species remains a major challenge for phylogenetic reconstruction. It is unlikely that the phylogeny of a single gene will represent the phylogeny of a species as a whole [1], but DNA sequence data across a large number of loci can be combined in order to obtain a consensus tree [2]. Long sequences are needed, however, to minimize the effect of (infrequent) base substitutions, and sufficient individuals must be sequenced per species to account for intraspecific polymorphisms, an overwhelming task using current DNA sequencing technology. By contrast, microsatellites are easy to type [3], allowing the analysis of many loci in multiple individuals. Despite their successful use in mapping [4,5], behavioural ecology [6] and population genetics [7], their usefulness for the phylogenetic reconstruction of closely related taxa has never been demonstrated, even though microsatellites are often conserved across species [8-10]. One drawback to microsatellite use is their high mutation rate (10(-4)-10(-2)), combined with an incomplete understanding of their mutation patterns. Many microsatellites are available for Drosophila melanogaster, and they are distributed throughout the genome [11]. Most can be amplified in the D. melanogaster species complex [12,13] and have low mutation rates [14, 15]. We show that microsatellite-specific distance measurements [16] correlate with other multilocus distances, such as those obtained from DNA-DNA hybridization data. Thus microsatellites may provide an ideal tool for building multilocus phylogenies. Our phylogenetic reconstruction of the D. melanogaster complex provides strong evidence that D. sechellia arose first, followed by a split between D. simulans and D. mauritiana.     

A comparative analysis of Ungulata species by different molecular genetic markers (proteins, RAPD-PCR)]

The investigation of genetic interrelation between a number of Artiodactyla and Perissodactyla species with the use of different types of molecular-genetic markers (proteins, RAPD-PCR) were carried out. The marker-specific features of interspecific relations and their similarities on the groups of markers of both types were revealed. The distinctions between interspecies genetic relations and ones estimated from the phylogeny on the determined group of different types of markers were observed. It was supposed that these discrepancies may be related with common selection factors and involving this marker group in selection in some species.     

Genetic analysis on the role of integrin during axon guidance in Drosophila

Heterodimeric cell surface receptor integrin is widely expressed in the nervous system, but its specific role during axon development has not been directly tested in vivo. We show that the Drosophila nervous system expresses low levels of positron-specific (PS) integrin subunits alphaPS1, alphaPS2, and betaPS during embryonic axogenesis. Furthermore, certain subsets of neurons express higher levels of integrin mRNAs than do the rest. Null mutations in either the alphaPS1 or alphaPS2 subunit gene cause widespread axon pathfinding errors that can be rescued by supplying the wild-type integrin subunit to the mutant nervous system. In contrast, misexpressing either the alphaPS1 or alphaPS2 integrin subunit in all neurons leads to no obvious axon pathfinding errors. We propose that integrin does not itself serve as either a "clutch" constituting molecule or a specific growth cone "receptor," as proposed previously, but rather as part of a molecular network that cooperatively guarantees accurate axon guidance.     

decapentaplegic is required for arrest in G1 phase during Drosophila eye development

During eye development in Drosophila, cell cycle progression is coordinated with differentiation. Prior to differentiation, cells arrest in G1 phase anterior to and within the morphogenetic furrow. We show that Decapentaplegic (Dpp), a TGF-&bgr; family member, is required to establish this G1 arrest, since Dpp-unresponsive cells located in the anterior half of the morphogenetic furrow show ectopic S phases and ectopic expression of the cell cycle regulators Cyclins A, E and B. Conversely, ubiquitous over-expression of Dpp in the eye imaginal disc transiently inhibits S phase without affecting Cyclin E or Cyclin A abundance. This Dpp-mediated inhibition of S phase occurs independently of the Cyclin A inhibitor Roughex and of the expression of Dacapo, a Cyclin E-Cdk2 inhibitor. Furthermore, Dpp-signaling genes interact genetically with a hypomorphic cyclin E allele. Taken together our results suggest that Dpp acts to induce G1 arrest in the anterior part of the morphogenetic furrow by a novel inhibitory mechanism. In addition, our results provide evidence for a Dpp-independent mechanism that acts in the posterior part of the morphogenetic furrow to maintain G1 arrest.     

闽台入境旅游时空发展格局比较分析

闽台入境旅游发展存在明显的时空差异.虽然福建省的土地面积和人口数均大于台湾地区,但历年接待的入境旅游人数却明显少于台湾,只是差距正在不断缩小.目前,闽台国际入境旅游客源国分别以美国和日本居首位.虽然历年入境旅游收入福建省远低于台湾地区,但其占CDP的比重二者渐趋一致.闽台入境旅游发展的时空差异是多因素综合作用的结果.其中,台湾入境旅游发展较早,在市场竞争中占据先机具有重要影响;两地旅游发展政策和经济发展轨迹不同等方面也有一定的影响.