Nup154, a new Drosophila gene essential for male and female gametogenesis is related to the nup155 vertebrate nucleoporin gene.

The Nup154 gene of Drosophila encodes a protein showing similarity with known nucleoporins: rat Nup155 and yeast Nup170 and Nup157. Hypomorphic mutant alleles of Nup154 affected female and male fertility, allowing investigation of the gene function in various steps of oogenesis and spermatogenesis. Nup154 was required in testes for cyst formation, control of spermatocyte proliferation and meiotic progression. In ovaries, Nup154 was essential for egg chamber development and oocyte growth. In both the male and female germ line, as well as in several other cell types, the Nup154 protein was detected at the nuclear membrane, but was also present inside the nucleus. Intranuclear localization has not previously been described for rat Nup155 or yeast Nup170 and Nup157. In mutant egg chambers the Nup154 protein accumulated in the cytoplasm, while it was only barely detected at the nuclear envelopes. FG repeats containing nucleoporins detected with mAb414 antibody were also mislocalized to a certain extent in Nup154 mutant alleles. This suggests that Nup154 could be required for localizing other nucleoporins within the nuclear pore complex, as previously demonstrated for the yeast Nup170. On the other hand, no evident defects in lamin localization were observed, indicating that Nup155 mutations did not affect the overall integrity of the nuclear envelope. However, ultrastructural analyses revealed that in mutant cells the morphology of the nuclear envelope was altered near the nuclear pore complexes. Finally, the multiplicity of phenotypes observed in Nup154 mutant alleles suggests that this gene plays a crucial role in cell physiology.

Non-random loss of uninterrupted ribosomal DNA repeating units upon induction of a bobbed mutation.

To investigate the physical organization of ribosomal RNA genes of two bobbed (bb) loci carried by the Dp(1;f)122 free duplication, a wild type and a deleted one derived from it, genomic DNAs from XXNO-/Dp122bb+ and XXNO-/Dp122bb adult females were analyzed by restriction enzyme digestions. We found that in the bb mutant there was a loss of uninterrupted genes, while genes interrupted by type I and type II insertions remained apparently unchanged. This is an indication that at least in this wild type bb+ locus, carried by the 122 free duplication, the different repeating units are not distributed randomly. In fact, after digestion of the rDNA carried by the bb+ duplication with the enzyme BamHI that cuts only in type I insertions, we have obtained long uncleaved fragments of DNA containing uninterrupted genes.

The Drosophila melanogaster lipase homologs: a gene family with tissue and developmental specific expression.

We report the molecular cloning of Drosophila genes encoding putative lipase homologs, Dm lip1, lip2 and lip3, the definition of their structure and the expression patterns during development. These Drosophila lipases are related to acid lipases, with a common GHSQG motif, within a more general consensus GXSXG, identified as the active site shared by all the members of lipase superfamily. The lip1 and lip3 genes are transcribed in different tissues and developmental stages, suggesting that they have different functions. The lip1 gene, coding for a protein similar to digestive lipases, is expressed in ovaries and early embryos and, with a different sized transcript, in all the other developmental stages. The lip3 gene, whose translation product is more similar to lysosomal acid lipases, is expressed only during the larval period. The lip2 gene seems non-functional. The Drosophila putative lipases do not show similarity with the Drosophila yolk proteins that are reported to have sequence similarity with lipoprotein lipases, but share a consistent similarity with lepidopteran proteins reported as egg specific or yolk proteins, probably corresponding to lipase homologs. The results reported here are discussed in relation to the evolution and functions of lipases within the between species.

The abnormal oocyte phenotype is correlated with the presence of blood transposon in Drosophila melanogaster.

The abnormal oocyte mutation (2;44) originates in the wild: it confers no visible phenotype on homozygous abo males or females, but homozygous abo females produce defective eggs and the probability of their developing into adults is much lower than that of heterozygous sister females. We isolated by chromosome walking 200 kb of DNA from region 32. This paper reports that a restriction enzyme site polymorphism analysis in wild type and mutant stocks allowed us to identify a DNA rearrangement present only in stocks carrying the abo mutation. The rearrangement is caused by a DNA insert on the abo chromosome in region 32E which, by restriction map and sequence analysis, was identified as copia-like blood transposon. The transposon, in strains that had remained in abo homozygous conditions for several generations and had lost the abo maternal-effect, was no longer present in region 32E. Certain features of the abo mutation, discussed in the light of this finding, may be ascribed to the nature of the particular allele studied.

Maternal and Zygotic Interactions between the Abnormal Oocyte Mutation and the Scute Inversion in DROSOPHILA MELANOGASTER.

The authors have studied the interaction between the abnormal oocyte mutation and an inversion of the X chromosome, In( 1)sc(4), which has a proximal breakpoint in or near the heterochromatic region (ABO) that maternally interacts with the abo product. It has been demonstrated that the presence of X chromosomes carrying this inversion, besides a marked increase in the severity of the maternal effect of the abo mutation, produces a zygotic effect resulting in the lethality of the progeny of stocks homozygous for abo and sc(4). These results indicate that the sc(4) inversion carries an abnormal region indispensable for the development of abo zygotes from sc(4);abo mothers.

hold up is required for establishment of oocyte positioning, follicle cell fate and egg polarity and cooperates with Egfr during Drosophila oogenesis.

In Drosophila the posterior positioning of the oocyte within the germline cluster defines the initial asymmetry during oogenesis. From this early event, specification of both body axes is controlled through reciprocal signaling between germline and soma. Here it is shown that the mutation hold up (hup) affects oocyte positioning in the egg chamber, follicle cell fate and localization of different markers in the growing oocytes. This occurs not only in dicephalic egg chambers, but also in oocytes normally located at the posterior. Generation of mosaic egg chambers indicates that hup has to be at least somatically required. Possible interactions of hup with Egfr, the Drosophila epidermal growth factor receptor homolog, have been investigated in homozygous double mutants constructed by recombination. Stronger new ovarian phenotypes have been obtained, the most striking being accumulation of follicle cells in multiple layers posteriorly to the oocyte. It is proposed that the hup gene product is a component of the molecular machinery that leads to the establishment of polarity both in follicle cell layer and oocyte, acting in the same or in a parallel pathway of Egfr.

Cellular specificity of expression and regulation of Drosophila vitelline membrane protein 32E gene in the follicular epithelium: identification of cis-acting elements.

In this paper we analyze the expression in follicular cells and regulation of the vitelline membrane protein gene we identified in region 32E of the second chromosome of D. melanogaster (VMP32E). We report germ line transformation results obtained with different kinds of gene fusion leading to the identification of a follicular cell subpopulation involved in the expression of the VMP32E. We have characterized two 5' non-transcribed regions (-465/-249; -135/-39) where the cis-acting transcriptional regulatory sequences, directing tissue and temporal specificity, are contained. The region between -465 and -249, which appears to control transcriptional high efficiency, does not behave as an enhancer as it is incapable of conferring any expression to a reporter gene. The region between -135 and -39 can confer temporal specificity of expression of the VMP32E gene, albeit at a very low level. Most interestingly, sequence similarities to ecdysone response elements raise the possibility of hormonal control also for VMP gene expression.

Organisation of regulatory elements in two closely spaced Drosophila genes with common expression characteristics.

Sperm tail proteins that are components of a specific structure formed late during spermatid elongation have been found to be encoded by the Mst(3)CGP gene family. These genes have been demonstrated to be regulated both at the transcriptional as well as at the translational level. We report here on the dissection of the regulatory regions for two members of the gene family, Mst84Da and Mst84Db. While high level transcription and negative translational control of Mst84Da is mediated by a short gene segment of 205 nt (-152/+53), Mst84Db expression is controlled by a number of distinct regulatory elements with different effects that all reside within the gene itself. We identify a transcriptional control element between +154 and +216, a translational repression element around +216 to +275 and an RNA stability element within the 3'UTR. Irrespective of the final common expression characteristics, correct regulation for any individual member of the gene family seems to be achieved by very different means. This confirms earlier observations that did not detect any other sequence elements in common apart from the TCE (translational control element).

Female sterile mutations and egg chamber development in Drosophila melanogaster.

Drosophila oogenesis provides an excellent opportunity to study fundamental aspects of developmental biology and to learn the importance of multiple signalling pathways in the regulation of cellular morphogenesis. Taking advantage of the genetic and molecular approaches extremely powerful in this organism, over the years an enormous collection of data has accumulated on the genes involved in important steps of egg chamber development, such as germline and somatic stem cell maintenance, division and differentiation; oocyte determination and positioning; establishment of follicle cell fate and axes formation. These different processes are mediated by a reciprocal cross-talk between germline and somatic follicle cells. Here, in a schematic and simplified form, we point out what we believe are the main recent results on the molecular and cellular mechanisms underlying ovarian development and outline our recent contribution to this field.

Leucotomized and nonleucotomized schizophrenics: comparison on tests of attention.

Deficits in attention have been strongly linked with both schizophrenia and pathology in the prefrontal cortex. This observation was tested by administering a battery of commonly used tests of attention, sustained mental activity, and tracking to 16 patients who had undergone prefrontal leucotomy approximately 25 years earlier. Presurgical diagnosis in each patient was schizophrenia. The 16 were divided into three groups based on their recovery after surgery. A control group of nonleucotomized schizophrenics was established to control for psychiatric symptomatology. A second control group consisted of subjects without history of psychiatric or CNS disorder. In general, there was no statistically significant impairment of performance in attention tests between the patients with prefrontal psychosurgery and the normal control subjects. The nonoperated schizophrenic control group performed most poorly. Lesion chronicity, interaction of leucotomy and presurgical psychiatric state, and conditions of test administration are suggested as possible explanations for the unexpected results.

Synthesis and expression of genes encoding putative insect neuropeptide precursors in tobacco.

Neuropeptides are the key molecules in a multiplicity of physiological processes and their use in pest control has recently been suggested. Most neuropeptides are produced in the form of a precursor that is cleaved by proteolysis to yield various biologically active peptides. To mimic this structure, a method has been developed for synthesizing genes that code for putative polyneuropeptide precursors. As a model neuropeptide, the 5-amino-acid proctolin, one of the best studied invertebrate neuropeptides, functioning both as a visceral and a skeletal neuromuscular transmitter, was chosen. The synthetic gene was introduced into bacteria and tobacco plants, where it was efficiently transcribed. We present our results as a possible approach for the expression, in a variety of organisms, of synthetic genes coding for a wide repertoire of insect neuropeptides.

Capture errors and sequencing after frontal brain lesions.

This study addresses the effect of strong routine associations (capture errors) in hindering the control of on-line serial or sequencing tasks. Patients with focal frontal lobe lesions were significantly inferior to normal control subjects and patients with posterior brain lesions, when conditions that may lead to capture errors were present. The results suggest that the primary dysfunction exhibited by patients with frontal lobe lesions on capture error tasks may lie not in the disengagement from the invalid associations but in focusing attention to alternative strategies of response.

Characterization of Aphidius ervi (Hymenoptera, Braconidae) ribosomal genes and identification of site-specific insertion elements belonging to the non-LTR retrotransposon family.

We performed a molecular analysis of the Aphidius ervi ribosomal gene structure. This insect belongs to a set of closely related Aphidiinae species of the genus Aphidius Nees, of relevant interest in biological control. We constructed A. ervi genomic libraries, cloned and characterized several rDNA repeating units and sequenced different regions of the rDNA cistrons. We have found that insertion sequences interrupt the A. ervi 28S rDNA genes: the sequences of the two 5' and 3' insertion-28S junctions show that the elements are present at the position where R1 elements have been found in various insect species. In addition, the insertion of the element produces a duplication of the 14 nt target region. The sequence analysis indicates that the A. ervi elements belong to the R1 retrotransposon family with a highly conserved reverse transcriptase domain.

Physiological and molecular interaction in the host-parasitoid system Heliothis virescens-Toxoneuron nigriceps: current status and future perspectives.

Toxoneuron nigriceps (Viereck) (Hymenoptera, Braconidae) is an endophagous parasitoid of the tobacco budworm Heliothis virescens (F.) (Lepidoptera, Noctuidae). Parasitized H. virescens larvae are developmentally arrested and show a complex array of pathological symptoms ranging from the suppression of the immune response to an alteration of ecdysone biosynthesis and metabolism. Most of these pathological syndromes are induced by the polydnavirus associated with T. nigriceps (TnBV). An overview of our recent research work on this system is described herein. The mechanisms involved in the disruption of the host hormonal balance have been further investigated, allowing to better define the physiological model previously proposed. A functional genomic approach has been undertaken to identify TnBV genes expressed in the host and to assess their role in the major parasitoid-induced pathologies. Some TnBV genes cloned so far are novel and do not show any similarity with genes already available in genomic databases, while others code for proteins having conserved domains, such as aspartic proteases and tyrosine phosphatases. Sequencing of the entire TnBV genome is in progress and will considerably contribute to the understanding of the molecular bases of parasitoid-induced host alterations.

Cardiochiles nigriceps polydnavirus: molecular characterization and gene expression in parasitized Heliothis virescens larvae.

Cardiochiles nigriceps Viereck is an endophagous parasitoid of larval stages of the tobacco budworm, Heliothis virescens (F.). This hymenopteran parasitoid, belonging to the family Braconidae, is associated with a polydnavirus (CnPDV), injected at ovi-position along with the egg. The infection of various tissues by CnPDV determines the suppression of the host immune system and the developmental arrest of mature host larvae. In this study, CnPDV has been characterized at the structural and molecular level. The negatively stained nucleocapsids show evident 'end structures' and a tail-like appendage. The CnPDV genome is typically segmented, with circular dsDNA molecules, ranging in size from 2.5 kb to more than 23 kb. The early expression pattern of CnPDV in parasitized hosts has been analysed and viral clones, genomic and cDNAs, identifying genes expressed within 48 h after parasitization have been isolated. The molecular organization of one of these genes, named CnPDV1, and its putative protein product have been determined. Significant sequence homologies with other known proteins were not detected. In situ hybridization experiments indicated that this gene is expressed in the prothoracic glands of parasitized host mature larvae. A functional analysis of CnPDV1 gene product is required to assess its possible role in the regulation of parasitoid-induced alterations of host larvae.

Language functioning after bilateral prefrontal leukotomy.

Three groups of patients with orbital frontal lesions secondary to leukotomy were compared to psychiatric and normal control groups on a series of tasks involving language. The results indicated that chronic orbital frontal lesions, at least in the patients in this study, do not affect language as defined by the tasks used in the study. The frontal lobes, when implicated in language, appear to require dorsal-lateral or medial cortical involvement.

A novel fatty acid binding protein produced by teratocytes of the aphid parasitoid Aphidius ervi.

Aphidius ervi is an endophagous braconid, parasitoid of the pea aphid, Acyrthosiphon pisum. A. ervi teratocytes, deriving from the dissociation of the embryonic serosa, synthesize and release two major proteins into the host haemocoel. The gene of one of these proteins has been cloned and characterized. This gene codes for a 15.8 kDa protein belonging to the fatty acid binding protein (FABP) family, named Ae-FABP (A. ervi-FABP). It is abundantly present in the host haemolymph when the parasitoid larva attains its maximum growth rate. The recombinant Ae-FABP binds to fatty acids in vitro, showing a high affinity to C14-C18 saturated fatty acids and to oleic and arachidonic acid. The possible nutritional role for the parasitoid larva of Ae-FABP is discussed.

Different behaviour of Xbb+ and Xbb chromosomes in D. melanogaster with only one nucleolus organizer.

We have examined the rDNA content of male and female adult flies having only one nucleolus organizer (NO), using X chromosomes carrying wild or partially deleted bobbed loci (Xbb+/O, Xbb+/XNO- and Xbb/O, Xbb/XNO-). The results show that in Xbb+/O and Xbb+/XNO- flies, where only somatic gene compensation is supposed to occur, the rDNA increase, althought less pronounced than previously reported, is directly proportional to the number of rRNA genes initially present in the nucleolus organizer. In Xbb/O and in Xbb/Xbb/XNO- flies the rDNA increase is relatively much higher than that observed in flies carrying bb+ instead of bb. It is suggested that this may be due to rDNA premagnification and somatic gene compensation occurring simultaneously in the former flies.