Stink Bug (Hemiptera: Pentatomidae) Occurrence, Reproduction, and Injury to Fruit in an Organic Tomato Crop Bordered by Sorghum.

Border rows of grain sorghum were planted along two to four sides of an organic Granadero tomato crop in North Florida to reduce fruit injury caused by native and invasive stink bugs. During the 2-yr study, 14 species of stink bugs were encountered, six only in sorghum: Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae), Thyanta spp., Oebalus pugnax (Fabricius), Chinavia hilaris (Say), C. pensylvanica (Gmelin), and Mormidea pama (Rolston). There were four species only in tomato: Euschistus obscurus (Palisot de Beauvois), E. tristigmus (Say), E. ictericus (L.), and Arvelius albopunctatus (De Geer). The three most abundant pests in tomato were collected in both crops: Nezara viridula (L.), Euschistus servus (Say), and E. quadrator Rolston, along with Proxys punctulatus (Palisot de Beauvois). Nezara viridula and P. guildinii were the most abundant stink bugs on sorghum. The border rows of sorghum did not reduce the total number of stink bug adults or nymphs in the tomato crop, although many more stink bug adults were captured in sorghum than tomato when the sorghum panicles were in the milk to soft dough stage. Generally, 30% of the females in the sorghum and tomato crops were mated and contained more than 15 eggs, indicating they could generate a considerable number of nymphs. Tomato fruit from the plot with sorghum border rows had significantly more punctures than fruit from the plot without sorghum. The stink bugs frequently probed and blemished tomato fruit in all stages of ripeness but fruit covered with probing sites were nevertheless suitable for human consumption.

Randomized clinical trial comparing self-expanding metallic stents with plastic endoprostheses in the palliation of oesophageal cancer.

BACKGROUND: There is little evidence of the clinical and cost effectiveness of self-expanding metallic stents in the palliation of oesophageal cancer. The aims of this randomized trial were to evaluate the immediate and medium-term clinical outcomes following palliative intubation, examine patient quality of life, and evaluate costs and benefits from the perspective of the health service. METHODS: Fifty patients with inoperable oesophageal cancer were randomly allocated a metallic stent (n = 25) or plastic endoprosthesis (n = 25). Patients were followed up monthly until death. RESULTS: There was no significant difference in procedure-related complications or mortality rate between the two groups. There was a trend towards significance in favour of metallic stents with respect to quality of life and survival (median survival 62 versus 107 days for plastic prosthesis and metallic stent respectively). The cost of the initial placement of metallic stents was significantly higher than that of plastic endoprostheses ( pound 983 versus pound 296). After 4 weeks, cost differences were no longer significant. CONCLUSION: Metallic stents may contribute to improved survival and quality of life in patients with oesophageal cancer. Although initially more expensive, this cost difference does not last beyond 4 weeks. A larger trial involving approximately 300 patients would be required to detect a quality of life benefit of the magnitude observed in this trial.

Structure and development of the pitchers from the carnivorous plantNepenthes alata (Nepenthaceae).

The pitchers of the tropical carnivorous plant Nepenthes alata are highly specialized organs for the attraction and capture of insects and absorption of nutrients from them. This study examined the structure and development of these pitchers, with particular focus on the nectaries and digestive glands. Immature pitchers developed at the tips of tendrils and were tightly sealed by a lid structure that opened during the end of pitcher elongation. Opened pitchers exposed a ridged peristome containing large nectaries. Like other members of the genus, a thick coating of epicuticular waxy scales covered the upper one-third of the pitcher. Scattered within this zone were cells resembling a stomatal complex with a protruding ridge. Cross sections showed that this ridge was formed by asymmetric divisions of the epidermal cells and lacked an underlying pore. The basal region of the trap had large multicellular glands that developed from single epidermal cells. These glands were closely associated with underlying vascular traces and provided a mechanism for supplying fluid to closed immature pitchers.

Protein N-glycosylation: molecular genetics and functional significance.

Protein N-glycosylation is a metabolic process that has been highly conserved in evolution. In all eukaryotes, N-glycosylation is obligatory for viability. It functions by modifying appropriate asparagine residues of proteins with oligosaccharide structures, thus influencing their properties and bioactivities. N-glycoprotein biosynthesis involves a multitude of enzymes, glycosyltransferases, and glycosidases, encoded by distinct genes. The majority of these enzymes are transmembrane proteins that function in the endoplasmic reticulum and Golgi apparatus in an ordered and well-orchestrated manner. The complexity of N-glycosylation is augmented by the fact that different asparagine residues within the same polypeptide may be modified with different oligosaccharide structures, and various proteins are distinguished from one another by the characteristics of their carbohydrate moieties. Furthermore, biological consequences of derivatization of proteins with N-glycans range from subtle to significant. In the past, all these features of N-glycosylation have posed a formidable challenge to an elucidation of the physiological role for this modification. Recent advances in molecular genetics, combined with the availability of diverse in vivo experimental systems ranging from yeast to transgenic mice, have expedited the identification, isolation, and characterization of N-glycosylation genes. As a result, rather unexpected information regarding relationships between N-glycosylation and other cellular functions--including secretion, cytoskeletal organization, proliferation, and apoptosis--has emerged. Concurrently, increased understanding of molecular details of N-glycosylation has facilitated the alignment between N-glycosylation deficiencies and human diseases, and has highlighted the possibility of using N-glycan expression on cells as potential determinants of disease and its progression. Recent studies suggest correlations between N-glycosylation capacities of cells and drug sensitivities, as well as susceptibility to infection. Therefore, knowledge of the regulatory features of N-glycosylation may prove useful in the design of novel therapeutics. While facing the demanding task of defining properties, functions, and regulation of the numerous, as yet uncharacterized, N-glycosylation genes, glycobiologists of the 21st century offer exciting possibilities for new approaches to disease diagnosis, prevention, and cure.

Molecular dissection of the genetic targets of ALG7 in the serpentine receptor-mediated signal transduction pathway in yeast.

These initial studies show that deregulated expression of ALG7 affects diverse cellular functions crucial to development, including proliferation, differentiation, and morphogenesis. Furthermore, the data suggest multiple genetic targets for ALG7 and provide the basis for future dissection of these developmentally relevant pathways.

Confocal imaging of gene expression during hamster submandibular gland biogenesis.

The data presented here provide evidence that the abundance of the ALG7 protein product, GPT, correlates with high proliferative activity during the postnatal development of the hamster SMG development, and that it becomes downregulated with differentiation. Based on our previous studies with yeast, changes in the level of ALG7 expression may be necessary for the events directing salivary cell polarization, migration, differentiation, and apoptosis at distinct developmental stages.

Characterization of multiple transcripts of the hamster dolichol-P-dependent N-acetylglucosamine-1-P transferase suggests functionally complex expression.

The evolutionarily conserved dolichol-P-dependent N-acetylglucosamine-1-P transferase gene, ALG7, functions by initiating the dolichol pathway of protein N-glycosylation. In yeast, ALG7 has a complex expression pattern and plays a critical role in diverse cellular functions, including proliferation and morphological response. In Chinese hamster ovary cells (CHO), ALG7 gives rise to three mRNAs of 1.5, 1.9 and 2.2 kb. We report results of RNA blotting assays, ribonuclease protection, PCR-amplification and sequencing of the CHO ALG7 transcripts 5' and 3' ends which suggest that the 1.5 and 1.9 kb transcripts are produced as a consequence of initiation at 2 distinct start sites, 350-379 bp apart. The transcriptional start site for the 1.5 kb mRNA is positioned between the first two in frame ATGs, while that of the 1.9 kb species is located upstream of these two in-frame ATGs. In order to test the translational competence of the 1.5 and 1.9 kb mRNAs, we constructed DNA templates specifying these transcripts and used them for in vitro transcription/translation. Our data show that the 1.9 kb mRNA served in the synthesis of 36 and 24 kDa species, as well as a low-abundance 32 kDa protein. The 1.5 kb transcript gave rise to a translation product of 32 kDa. The latter is synthesized in CHO cells and hamster submandibular glands. These results suggest the possibility that the 1.5 and 1.9 kb transcripts give rise to related protein isoforms with different lengths of their NH2-terminal regions.

Deregulation of the first N-glycosylation gene, ALG7, perturbs the expression of G1 cyclins and cell cycle arrest in Saccharomyces cerevisiae.

The evolutionarily conserved ALG7 gene encodes the dolichol-P-dependent N-acetylglucosamine-1-P transferase (GPT) and functions by initiating the dolichol pathway of protein N-glycosylation. In Saccharomyces cerevisiae, ALG7 has been shown to play a role in cell proliferation. The yeast alpha-factor-induced cell cycle arrest in G1 occurs, in part, by downregulation of CLN1 and CLN2. The function of ALG7 in G1 arrest was examined in alg7 mutants containing diminished GPT activity. In wild type, CLN1 and CLN2 mRNAs were rapidly downregulated, while in alg7 mutants, these transcripts were only transiently repressed before becoming greatly augmented. Analyses of DNA contents and budding indices showed that alg7 mutants resumed cycling when wild type cells remained arrested. Thus, deregulation of ALG7 interferes with cell cycle arrest by preventing a sustained downregulation of CLN1 and CLN2 mRNAs. These results provide a molecular insight into the role of ALG7, and protein N-glycosylation in general, in proliferation.

The dual role of mRNA half-lives in the expression of the yeast ALG7 gene.

The yeast ALG7 gene functions by initiating the synthesis of the dolichol-linked oligosaccharide precursor and plays an important role in the control of protein N-glycosylation. The levels of ALG7 multiple transcripts are modulated by the physiological status of the cell and environmental cues, and deregulation of their abundance is deleterious to several cellular functions. Since ALG7 mRNAs are unstable, we investigated the role of these transcripts' half-lives in determining their steady-state levels. Using a temperature-sensitive RNA polymerase II mutant, we demonstrate that increased stability was the primary determinant of higher ALG7 mRNA abundance in response to glucose limitation or treatment with tunicamycin. In contrast, at the G1/G0 transition point, changes in the decay rates were inversely related to ALG7 transcript accumulation: the decreased abundance of ALG7 mRNAs following exit from the mitotic cycle was associated with lengthening of the decay rates, while their increased accumulation after growth stimulation correlated with decreased stability. This suggests that, depending on the circumstance, mRNA half-lives can either directly determine the level of ALG7 transcript accumulation or oppose regulatory changes at other control levels.

Proliferation-dependent differential regulation of the dolichol pathway genes in Saccharomyces cerevisiae.

The dolichol pathway serves in the synthesis of the dolichol-linked oligosaccharide precursor for protein N-glycosylation. Recently, we reported that mRNAs of genes that function at the early steps in the dolichol pathway in yeast, ALG7, ALG1 and ALG2, were co-ordinately induced following growth stimulation of G0-arrested cells in a manner similar to that of the transcripts of the early growth response genes (Kukuruzinska, M.A. and Lennon, K. Glycobiology, 4, 437-443, 1994). To determine whether the entire dolichol pathway was co-ordinately regulated with growth, we examined the expression of genes functioning late in the pathway, including two genes encoding oligosaccharyltransferase subunits, at two critical control points in the G1 phase of cell cycle: G0/G1 and START. We show that early in G1, at the G0/G1 transition point, the late ALG genes and the two oligosaccharyltransferase-encoding genes examined were regulated co-ordinately with the early ALG genes: they were downregulated upon exit from the mitotic cell cycle into G0, and they were induced following growth stimulation in the absence of de novo protein synthesis. All the dolichol pathway genes produced transcripts with short half-lives that were rapidly stabilized in the presence of cycloheximide. In contrast, cell division arrest late in G1, at START, was accompanied by a selective downregulation of only the first dolichol pathway gene, ALG7, and not of the genes functioning later in the pathway. These results indicate that, depending on their position in G1, cells either co-ordinately or differentially regulate the dolichol pathway genes.

Expression of the first N-glycosylation gene in the dolichol pathway, ALG7, is regulated at two major control points in the G1 phase of the Saccharomyces cerevisiae cell cycle.

The Saccharomyces cerevisiae ALG7 gene, which functions by initiating the dolichol pathway of protein N-glycosylation, displays properties of an early growth-response gene. To initiate studies of the involvement of ALG7 in cellular proliferation, we have now more precisely analyzed ALG7 expression in the G1 phase of cell cycle. We show that the rapid rate of ALG7 mRNA accumulation following growth stimulation was attenuated soon thereafter and that ALG7 growth induction occurred irrespective of alpha-factor. ALG7 growth induction was observed in mutants conditionally defective for reentry into the cell cycle from the stationary phase, indicating that the induction occurred prior to the performance of START. In addition, the steady-state levels of ALG7 mRNAs declined four-fold in response to START-I cell division arrest brought about by alpha-factor treatment later in G1. Importantly, deregulated expression of ALG7 resulted in an aberrant alpha-factor response. Our data not only indicate that ALG7 expression is regulated at two critical control points in G1 that determine the proliferative potential of cells, but also provide a link between ALG7 and START.

Diminished activity of the first N-glycosylation enzyme, dolichol-P-dependent N-acetylglucosamine-1-P transferase (GPT), gives rise to mutant phenotypes in yeast.

The enzyme which initiates the dolichol pathway of protein N-glycosylation, dolichol-P-dependent N-acetylglucosamine-1-P transferase (GPT), is encoded by the ALG7 gene. Essential for viability, ALG7 has been evolutionarily conserved and shown to be involved in a variety of functions. ALG7 is an early growth-response gene in yeast, and downregulation of ALG7 expression results in diminished N-glycosylation and secretion of Xenopus oocyte proteins. We have now investigated the consequences of diminished GPT activity in yeast using mutant ALG7 genes with deletions in the 3' untranslated region (3' UTR). We show that a 2.5- to 4-fold reduction in GPT activity gave rise to distinct phenotypes, whose severity was inversely related to the level of GPT activity. These phenotypes included hypersensitivity to tunicamycin, enlarged cell size, extensive aggregation, lack of a typical stationary (G0) arrest, and defective spore germination. We conclude that yeast cells are sensitive to GPT dosage, and that attenuation of GPT activity interferes with various functions in the yeast life cycle.

Growth-related coordinate regulation of the early N-glycosylation genes in yeast.

The Saccharomyces cerevisiae ALG7, ALG1 and ALG2 genes, whose products function early in the dolichol pathway of protein N-glycosylation, are essential for cell viability, and perturbation in their expression causes G1-specific cell cycle arrest. Here, we show that expression of the ALG7, ALG1 and ALG2 genes is coordinately regulated at the G0/G1 transition point in the yeast life cycle. Carbon starvation, which induces cells to exit from the G1 stage of the mitotic cycle into G0, resulted in a time-dependent decrease in the levels of the early ALG genes' mRNAs. Accordingly, addition of glucose, which stimulates the G0-arrested cells to resume proliferation, resulted in a rapid induction of their mRNAs. Cycloheximide alone also induced the early ALG transcripts, albeit to a much lower extent than glucose. Simultaneous addition of glucose and cycloheximide caused superinduction of these mRNAs, indicating that more than one control level was involved in their activation. Consistent with this, rapid degradation of ALG7, ALG1 and ALG2 mRNAs was completely abolished in the presence of cycloheximide. These data suggest that in yeast, the early N-glycosylation genes are regulated in a manner similar to that of the early growth-response genes.

Volcanic gases: hydrogen burning at kilauea volcano, hawaii.

Spectroscopic evidence for hydrogen burning in air was obtained at Kilauea Volcano. The abundance of hydrogen required to support combustion is consistent with that predicted for gases in equilibrium with typical Hawaiian tholeiitic basalt.