Transcriptome analysis of the response of silkworm to drastic changes in ambient temperature

Bombyx mori is a poikilothermic insect and is economically important for silk production. Drastic changes in the ambient temperature have a negative impact on sericulture. However, the reason as to why high temperature is associated with the occurrence of diseases in silkworm and the response of silkworm to low temperature remain unclear and were the focus of the present study. Dazao silkworm exposed to 13 °C (DZ-13), 25 °C (DZ-25), and 37 °C (DZ-37) were used for RNA-seq analysis. There were 478 and 194 upregulated differentially expressed genes (DEGs) in DZ-13 and DZ-37 while 49 and 273 downregulated DEGs in DZ-13 and DZ-37, respectively. Eight DEGs were co-upregulated, in which seven genes were for heat shock proteins (Hsps), implying that Hsps play important roles in the tolerance of silkworm to high and low temperature. Gene ontology analysis revealed that the developmental process was downregulated in DZ-13. All the DEGs in the oxidative phosphorylation and insulin signaling pathways were upregulated in DZ-13. Several cuticular proteins and ATP synthesis-related genes were upregulated in DZ-13, suggesting that thickening of the cuticle and increase in the ATPase expression would help silkworms to protect themselves from low temperature-induced stress. Several immune-related genes, such as BmRel and BmSerpin-2, were downregulated in DZ-37, revealing that the resistance of silkworm is decreased under high temperature shock resulting in susceptibility to pathogens. Thus, the increase in the thermo-tolerance of silkworm should be related to the enhancement in the pathogen resistance.

     

Genome‐wide microarray screening for Bombyx mori genes related to transmitting the determination outcome of whether to produce diapause or nondiapause eggs

The bivoltine silkworm Bombyx mori (Lepidoptera: Bombycidae) exhibits a maternally controlled embryonic diapause. Maternal silkworms decide whether to lay diapause or nondiapause eggs depending on environmental factors such as the temperature and photoperiod during the egg and larval stages, and then induce diapause eggs during the pupal stage. However, little is known about the molecular mechanism that conveys the outcome of whether to produce diapause or nondiapause eggs from the egg or larval stages to the pupal stage. This study used microarray analysis to investigate differentially expressed genes in the larval brains of diapause‐ and nondiapause‐egg producers, to which bivoltine silkworms were destined by thermal or photic stimulation during the egg stage. The cytochrome P450 18a1 and Krüppel homolog 1 genes were upregulated in producers of diapause eggs compared with those of nondiapause eggs under both experimental conditions. Cytochrome P450 18a1 encodes a key enzyme for steroid hormone inactivation and Krüppel homolog 1 is an early juvenile hormone‐inducible gene that mediates the repression of metamorphosis. The upregulation of these genes during the larval stage might be involved in the signaling pathway that transmits information about the diapause program from the egg stage to the pupal stage in the silkworm.     

转录组和代谢组分析瘤菌根菌对铁皮石斛的促生机制

为筛选出促进铁皮石斛(Dendrobium officinale)生长的差异表达基因和差异代谢物,对瘤菌根菌与无菌盆栽铁皮石斛苗共生后形成的侧根根系进行转录组、代谢组和双组学联合分析。结果表明,转录组分析共找到262条差异表达基因富集到了35条通路中,其中内质网蛋白质加工通路途径的差异基因最多,其次为氨基糖和核苷酸糖代谢通路。代谢组分析共检测出194个差异代谢物富集到33个KEGG通路中,其中代谢途径的差异代谢物最多有133个,其次为不同环境的微生物代谢途径的差异代谢物有70个。通过联合分析,有9个差异基因的差异表达导致丝氨酸、谷氨酸、D-甘露糖和激素等代谢物的积累量发生变化,这可能是瘤菌根菌促进铁皮石斛生长的重要原因。因此,推测瘤菌根菌促进铁皮石斛生长与氨基酸、糖、植物激素的积累及相关基因的表达变化有关。     

Identification of genes differentially expressed during larval molting and metamorphosis of <Emphasis Type="Italic">Helicoverpa armigera</Emphasis>

Background  

Larval molting and metamorphosis are important physiological processes in the life cycle of the holometabolous insect. We used suppression subtractive hybridization (SSH) to identify genes differentially expressed during larval molting and metamorphosis.     

Transcriptome Profiling of Barley Cultivar Hua 30 MDEC in Response to <i>Agrobacterium</i> Infection

Agrobacterium-mediated transformation has been widely used in plants. However, the mechanism in plant cells’ response to Agrobacterium infection was very complex. The mechanism of the determinants in host cell remains obscure, especially in barley, which is recalcitrant for Agrobacterium-mediated transformation. In the present study, microspore-derived embryogenic calli (MDEC) from barley elite cultivar were employed as unique subjects to characterize the mechanisms during the Agrobacterium infection process. Hua 30 MDEC can be successfully infected by Agrobacterium. RNA-sequencing at different infection points (0, 2, 6, 12, 24 hpi) was performed. The average expressional intensity of the whole genomics increased from 0 to 2 hpi, and then decreased subsequently. More upregulated than downregulated differentially expressed genes (DEGs) were counted at the same time. GO enrichment analysis showed that protein modification was significantly overrepresented in upregulated DEGs. Chromosome-related biological processes, gene expression and cellular metabolic processes were significantly overrepresented in downregulated DEGs. KEGG analysis showed that plant defense responses, phenylpropanoid biosynthesis and biosynthesis of amino acids were significantly enriched across the infection time course. Nine DEGs related to defense responses were identified. All DEGs were upregulated from 2 to 24 hpi. We speculate that these genes are possibly related to Agrobacterium infection. These findings will provide deep insights into the molecular events occurring during the process of Agrobacterium-mediated transformation.