Population dynamics of the potato tuber moth on processing tomatoes in Israel

The potato tuber moth (PTM),Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), is a major pest of processing tomatoes,Lycopersicon esculentum Mill. (Solanaceae), in Israel. The larvae penetrate the tomato fruit through the stem end and present a serious threat to crop quality. Foliage and fruit samples were taken in nine commercial tomato fields located in Israel's three main tomato growing areas, two of which are potato growing areas as well. PTM was not found where potatoes were absent. Potato harvest in nearby fields was found to be the most significant factor affecting seasonal trends in PTM population density in tomatoes. All four larval instars were found in foliage on all sampling dates. Significantly higher proportions of first instars were found during the population density increase which followed potato harvest. Damaged fruits did not contain first instar larvae, indicating that PTM never undergoes complete development within tomato fruit. Fruit damage levels at harvest were positively correlated to the peak mean population densities on foliage and the date they were observed. In tomato fields not adjacent to potatoes, infestation was first observed at the edge of the field. Both before and after the potato harvest in nearby fields, population density at the edge of the field was significantly higher than at the center. In tomato fields adjacent to potatoes, no significant differences were found between population densities at the edge and center before the potatoes were harvested. After the potato harvest, population density at the center of tomato fields was higher than at the edge. Deceased, October 1988     

Role of intron-contained sequences in formation of moloney murine leukemia virus env mRNA.

Formation of the Moloney murine leukemia virus envelope mRNA involves the removal of a 5,185-base pair-long intron. Deletion analysis of two Moloney murine leukemia virus-derived expression vectors revealed the existence of two short regions within the viral intron which are required for the efficient formation of the spliced RNA species. One region was present upstream from the 3' splice junction, extended at least 85 nucleotides beyond the splice site, and was not more than 165 nucleotides long. As yeast polymerase II introns, the Moloney murine leukemia virus intron contains the sequence 5'-TACTAAC-3' 15 nucleotides upstream from the 3' splice site. A second region located in the middle of the intron, within a 560-nucleotide-long sequence, was also essential for formation of the spliced RNA species. The efficient splicing of the env mRNA in the absence of expression of viral genes raises the possibility that similar mechanisms are used to remove introns of (some) cellular genes.     

Sodium binding in Halobacterium halobium measured by the nuclear magnetic resonance technique

Relaxation time measurements T₁ and T₂ of sodium in Halobacterium halobium pellets were carried out at two frequencies. From those measurements, combined with intensity measurements of the sodium in the system, estimation of the properties of the sodium ions in the system was carried out. It is suggested that three types of sodium ions are present in the bacterial pellet. (A) The extracellular sodium with properties of free solution and (B) sodium which is in the pericellular volume between the cell wall and the cell membrane. There is an exchange between type A and type B sodium. The type B sodium has (e²qQ)/h = 3.7 · 10⁷ rad/s, τ_cB = 5.2 · 10⁻⁶ s and τ_B = 1 · 10⁻³ s. The sodium of type C is bound inside the cell and undetected. It's concentration inside the cell is assumed to be 1.9 M.     

Changing places: a novel type of niche and stem cell coordination in the Drosophila ovary

The Drosophila ovary has been a favorite model for the study of stem cells within their niche. In this issue of Cell Stem Cell, Nystul and Spradling (2007) study somatic stem cells within a novel kind of niche and reveal the complexity and coordination of stem cell behavior.     

The tomato homolog of the gene encoding UV-damaged DNA binding protein 1 (DDB1) underlined as the gene that causes the<Emphasis Type="Italic"> high pigment-1</Emphasis> mutant phenotype

A tomato EST sequence, highly homologous to the human and Arabidopsis thaliana UV-damaged DNA binding protein 1 (DDB1), was mapped to the centromeric region of the tomato chromosome 2. This region was previously shown to harbor the HP-1 gene, encoding the high pigment-1 (hp-1) and the high pigment-1^w (hp-1^w) mutant phenotypes. Recent results also show that the A. thaliana DDB1 protein interacts both genetically and biochemically with the protein encoded by DEETIOLATED1, a gene carrying three tomato mutations that are in many respects isophenotypic to hp-1: high pigment-2 (hp-2), high pigment-2^j (hp-2^j) and dark green (dg). The entire coding region of the DDB1 gene was sequenced in an hp-1 mutant and its near-isogenic normal plant in the cv. Ailsa Craig background, and also in an hp-1^w mutant and its isogenic normal plant in the GT breeding line background. Sequence analysis revealed a single A⁹³¹-to-T⁹³¹ base transversion in the coding sequence of the DDB1 gene in the hp-1 mutant plants. This transversion results in the substitution of the conserved asparagine at position 311 to a tyrosine residue. In the hp-1^w mutant, on the other hand, a single G²³⁹²-to-A²³⁹² transition was observed, resulting in the substitution of the conserved glutamic acid at position 798 to a lysine residue. The single nucleotide polymorphism that differentiates hp-1 mutant and normal plants in the cv. Ailsa Craig background was used to design a pyrosequencing genotyping system. Analysis of a resource F₂ population segregating for the hp-1 mutation revealed a very strong linkage association between the DDB1 locus and the photomorphogenic response of the seedlings, measured as hypocotyl length (25<LOD score<26, R²=62.8%). These results strongly support the hypothesis that DDB1 is the gene encoding the hp-1 and hp-1^w mutant phenotypes.Communicated by R. Hagemann     

Repression of primordial germ cell differentiation parallels germ line stem cell maintenance

In Drosophila, primordial germ cells (PGCs) are set aside from somatic cells and subsequently migrate through the embryo and associate with somatic gonadal cells to form the embryonic gonad. During larval stages, PGCs proliferate in the female gonad, and a subset of PGCs are selected at late larval stages to become germ line stem cells (GSCs), the source of continuous egg production throughout adulthood. However, the degree of similarity between PGCs and the self-renewing GSCs is unclear. Here we show that many of the genes that are required for GSC maintenance in adults are also required to prevent precocious differentiation of PGCs within the larval ovary. We show that following overexpression of the GSC-differentiation gene bag of marbles (bam), PGCs differentiate to form cysts without becoming GSCs. Furthermore, PGCs that are mutant for nanos (nos), pumilio (pum) or for signaling components of the decapentaplegic (dpp) pathway also differentiate. The similarity in the genes necessary for GSC maintenance and the repression of PGC differentiation suggest that PGCs and GSCs may be functionally equivalent and that the larval gonad functions as a "PGC niche".     

Case study of circadian rhythm sleep disorder following haloperidol treatment: reversal by risperidone and melatonin

A patient with Gilles de la Tourette syndrome treated with haloperidol, ingested once daily after awakening from sleep, exhibited an irregular sleep-wake pattern with a free-running component of approximately 48 h. Transfer to risperidone, ingested once daily after awakening from sleep, was beneficial resulting in a sleep-wake cycle more synchronized at the appropriate phase to the external zeitgebers, and fewer nocturnal disturbances. The circadian sleep-wake schedule was fully synchronized when the patient had been subsequently treated with melatonin at 21:00h, before intended nocturnal sleep, in addition to risperidone in the morning. Restoration of the sleep-wake circadian pattern was accompanied by the patient's subjective report of significant improvement in his quality of life, social interactions, and occupational status. This observation suggests that circadian rhythm sleep disorders can be related to the typical neuroleptic haloperidol and restored by the atypical neuroleptic risperidone. Similar findings reported in patients suffering from other disorders support the hypothesis that the described disruption of the sleep-wake schedule is medication rather than illness-related. Therefore, it is very important to realize that circadian rhythm sleep disorders may be a side effect of neuroleptics.