Differential gene expression in whitefly Bemisia tabaci-infested tomato (Solanum lycopersicum) plants at progressing developmental stages of the insect's life cycle

A suppression-subtractive-hybridization (SSH) strategy was used to identify genes whose expression was modified in response to virus-free whitefly Bemisia tabaci ( Bt , biotype A) infestation in tomato ( Solanum lycopersicum ) plants. Thus, forward and reverse SSH gene libraries were generated at four points in the whitefly's life cycle, namely at (1) 2 days (adult feeding and oviposition: phase I); (2) 7 days (mobile crawler stage: phase II); (3) 12 days (second to third instar nymphal transition: phase III) and (4) 18 days (fourth instar nymphal stage: phase IV). The 169 genes with altered expression (up and downregulated) that were identified in the eight generated SSH libraries, together with 75 additional genes that were selected on the basis of their involvement in resistance responses against phytofagous insects and pathogens, were printed on a Nexterion^® Slide MPX 16 to monitor their pattern of expression at the above phases. The results indicated that Bt infestation in tomato led to distinctive phase-specific expression/repression patterns of several genes associated predominantly with photosynthesis, senescence, secondary metabolism and (a)biotic stress. Most of the gene expression modifications were detected in phase III, coinciding with intense larval feeding, whereas fewer changes were detected in phases I and IV. These results complement previously reported gene expression profiles in Bt -infested tomato and Arabidopisis, and support and expand the opinion that Bt infestation leads to the downregulation of specific defense responses in addition to those controlled by jasmonic acid.     

Effect of the light on adenine nucleotide content of georeacting maize roots

Apical segments from maize roots of LG 11 and Orla 264 varietiesgeoreacted, at least for the first few hours, only in light,while those of the Anjou 210 variety were georeactive both inlight and darkness. The energy charge in the apical end of thetwo light geo-sensitive (LG and Orla) maize roots significantlyincreased in the light. In contrast, in Anjou root tips, theenergy charge was already high in the dark and did not changesignificantly after light exposure. The time course of light-inducedchanges in adenine nucleotide contents in root tips was comparedwith varietal differences in georeactivity in light and darkness.The present data corroborate the hypothesis that a high energystate in the root tip is a prerequisite for the expression ofthe root reaction to gravity. (Received October 17, 1978; )     

Down-regulation of miR-17 family expression in response to retinoic acid induced neuronal differentiation

Whole-genome microRNA and gene expression analyses were used to monitor changes during retinoic acid induced differentiation of neuroblasts in vitro. Interestingly, the entire miR-17 family was over-represented among the down-regulated miRNA. The implications of these changes are considerable, as target gene prediction suggests that the miR-17 family is involved in the regulation of the mitogen-activated protein kinase (MAPK) signaling pathway, synaptic plasticity and other markers of neuronal differentiation. Significantly, many of the target responses predicted by changes in miRNA expression were supported by the observed changes in gene expression. As expected, markers of neuronal differentiation such as anti-apoptotic protein B-cell lymphoma 2 (BCL2), myocyte enhancer factor-2D (MEF2D) and zipper protein kinase (MAP3K12; aka ZPK/MUK/DLK) were each up-regulated in response to differentiation. The expression of these genes was also reduced in response to miR-17 and miR-20a transfection, and more specifically they were also shown to contain functional miRNA recognition elements for members of the miR-17 family by reporter gene assay. This suggests that the miR-17 family have an integral role in fine-tuning the pathways involved in the regulation of neuronal differentiation.     

The human aldose reductase gene maps to chromosome region 7q35

Summary The human aldose reductase (AR) gene has been mapped to chromosome 7 using the polymerase chain reaction to specifically amplify the human AR sequence in hamster/human hybrid DNA and also in mouse/ human monochromosome hybrids. The assignment to chromosome 7 was confirmed by in situ hybridisation to human metaphase chromosomes using a novel, rapid hybridisation, method giving a regional localisation at 7q35.     

Splicing of the Muscle-Specific Plasma Membrane Ca2+-ATPase Isoform PMCA1c Is Associated with Cell Fusion in C2 Myocytes

Abstract: The regulation of intracellular calcium is essential for proper muscle function. Muscle cells have several mechanisms for dealing with the rapid and large changes in cytosolic calcium level that occur during contraction. Among these is the plasma membrane Ca²⁺-ATPase (PMCA), which pumps calcium from the cytosol to the extracellular space. We have previously shown that in human fetal muscle the PMCA1 isoforms present are PMCA1a-d, with PMCA1b and c predominating. Alternative splicing of mRNAs encoding proteins involved in muscle contraction is common in developing muscle. Therefore, we examined the expression of muscle-specific PMCA mRNAs in pre- and postfusion mouse C2 myoblasts. The housekeeping form of the Ca²⁺-ATPase, PMCA1b, was found at all times and under all conditions. However, the other predominating isoform found in muscle, PMCA1c, was expressed on myotube formation. Simple cell-cell contact was not sufficient to induce PMCA1c expression, as cells plated at confluence but harvested before myotube formation did not express PMCA1c. The induction of this muscle-specific Ca²⁺-ATPase at myotube formation suggests that it may play an important role in muscle function.