Maternal effect of a hybrid inviability gene in Tribolium castaneum

The Tribolium castaneum hybrid inviability gene, H, was selectively introgressed into a genetic background lacking H through serial paternal backcrosses. This revealed a poor viability phenotype (partial paralysis and poor control of the limbs, referred to as tremor) not present in the parent strains. Tremor cosegregated with H, but was expressed only when transmitted paternally and only when H was not also present maternally. The inferred maternal, self‐suppressive effect of H may explain nonreciprocal incompatibilty previously observed between H and H‐incompatible strains. This revised version was published online in July 2006 with corrections to the Cover Date.     

Efficacy of Beauveria bassiana for control of Tribolium castaneum with reduced oxygen and increased carbon dioxide

This study investigated the effect of atmosphere modification, a widely adopted means of insect control in stored products, on the efficacy of Beauveria bassiana for one of the most difficult to control pests, Tribolium castaneum. Oxygen reduction to 5% (±1%) as opposed to CO₂ elevation to 40% (±2%) for the first 72 h of fungus exposure resulted in significantly greater larval mortality than fungus exposure under ambient atmospheres. Both treatments reduced pupation of older larvae suggesting that slowed development may be a beneficial factor for fungal efficacy. CO₂ elevation but not O₂ reduction significantly affected the mortality of adult beetles that were exposed to the fungus. Carbon dioxide elevation significantly reduced B. bassiana’s germination and growth rates, but oxygen reduction did not.     

磷化氢对赤拟谷盗成虫体内CAT和SOD活性的影响

用赤拟谷盗Tribolium castaneum(Herbst)成虫,研究PH3对其体内超氧化物岐化酶(SOD)和过氧化氢酶(CAT)活性的影响。结果表明PH3熏蒸后,4种不同地理种群的成虫体内,CAT酶活性都有所降低。种群NGD1降低最多,接近57%,而NGD4则只降低了19%,NGD2和NGD3的降低都在40%左右。不同地理种群的成虫体内,SOD酶活性在熏蒸后都有所增加,种群NGD1增加幅度最大,NGD2增加幅度最小。SOD和CAT活性的变化幅度与成虫对PH3产生的抗性有关,抗性越大,酶活性变化越大。     

赤拟谷盗功能基因组学研究进展

赤拟谷盗Tribolium castaneum是一种重要的模式生物,在遗传、发育、生化与免疫等研究领域均取得了重要的研究进展。同时它也是一种危害极大的鞘翅目类储粮害虫,在世界各地都有分布,每年给储藏物造成了数十亿美元的经济损失。其全基因组测序的完成、遗传操作体系的构建及系统RNAi方法的应用都极大地促进了其功能基因组学的研究。本文综述了近年来赤拟谷盗基因组计划及功能基因组学的研究进展,拟为赤拟谷盗的生物学研究和防治奠定基础。     

First evidence of DNA methylation in insect Tribolium castaneum

DNA methylation has been studied in many eukaryotic organisms, in particular vertebrates, and was implicated in developmental and phenotypic variations. Little is known about the role of DNA methylation in invertebrates, although insects are considered as excellent models for studying the evolution of DNA methylation. In the red flour beetle, Tribolium castaneum (Tenebrionidae, Coleoptera), no evidence of DNA methylation has been found till now. In this paper, a cytosine methylation in Tribolium castaneum embryos was detected by methylation sensitive restriction endonucleases and immuno-dot blot assay. DNA methylation in embryos is followed by a global demethylation in larvae, pupae and adults. DNA demethylation seems to proceed actively through 5-hydroxymethylcytosine, most probably by the action of TET enzyme. Bisulfite sequencing of a highly abundant satellite DNA located in pericentromeric heterochromatin revealed similar profile of cytosine methylation in adults and embryos. Cytosine methylation was not only restricted to CpG sites but was found at CpA, CpT and CpC sites. In addition, complete cytosine demethylation of heterochromatic satellite DNA was induced by heat stress. The results reveal existence of DNA methylation cycling in T. castaneum ranging from strong overall cytosine methylation in embryos to a weak DNA methylation in other developmental stages. Nevertheless, DNA methylation is preserved within heterochromatin during development, indicating its role in heterochromatin formation and maintenance. It is, however, strongly affected by heat stress, suggesting a role for DNA methylation in heterochromatin structure modulation during heat stress response.     

A convenient electrochemical preparation of reduced methyl viologen and a kinetic study of the reaction with oxygen using an anaerobic stopped-flow apparatus

1. Single reduced methyl viologen (MV^.+) acts as an electron donor in a number of enzyme systems. The large changes in extinction coefficient upon oxidation (λ_max 600 nm; MV^.+, = 1.3 · 10⁴ M⁻¹ · cm⁻¹; oxidised form of methyl viologen (MV²⁺), = 0.0) make it ideally suited to kinetic studies of electron transfer reactions using stopped-flow and standard spectrophotometric techniques.

2. A convenient electrochemical preparation of large amounts of MV^.+ has been developed.

3. A commercial stopped-flow apparatus was modified in order to obtain a high degree of anaerobicity.

4. The reaction of MV^.+ with O₂ produced H₂O₂ (k > 5 · 10⁶ M⁻¹ · s⁻¹, pH 7.5, 25 °C). H₂O₂ subsequently reacted with excess MV^.+ (k = 2.3 · 10³ M⁻¹ · s⁻¹, pH 7.5, 25 °C) to produce water. The kinetics of this reaction were complex and have only been interpreted over a limited range of concentrations.

5. The results support the theory that the herbicidal action of methyl viologen (Paraquat, Gramoxone) is due to H₂O₂ (or radicals derived from H₂O₂) induced damage of plant cell membrane.     

Two orthodenticle-related genes in the short-germ beetle Tribolium castaneum

 To investigate the molecular basis of head evolution, we searched for genes related to the Drosophila orthodenticle (otd) homeobox gene in the short-germ beetle Tribolium castaneum. Unexpectedly, we found that there are two otd-related genes in Tribolium, with predicted homeodomains highly similar to that of the single Drosophila gene. One of the two genes (Tc otd-1) is more related in both amino acid sequence and expression pattern to fruitfly otd. Tc otd-1 is expressed in a broad anterior stripe in the blastoderm embryo, suggesting a role in early head segmentation similar to that of the Drosophila gene. The second gene (Tc otd-2) is more similar in sequence to the otd-related genes isolated from different vertebrate species (the Otx gene family). Tc otd-2 is not transcribed in the blastoderm, but is expressed later in more limited subsets of cells in the anterior brain. Both Tribolium genes and the Drosophila gene are, unlike the vertebrate genes, also expressed at the developing ventral midline of the embryo. Our results are consistent with the idea that an otd/Otx gene specified anterior head structures in the last ancestor common to arthropods and vertebrates. Within the arthropod lineage, we propose that this gene acquired a function in cells at the developing midline prior to the duplication that generated the two Tribolium genes. Received: 16 February 1996 / Accepted: 1 March 1996 Edited by C. Desplan     

Improved growth and water use efficiency of cherry saplings under reduced light intensity

Cherry (Prunus avium L.) saplings were grown under natural sunlight (controls) or moderate shading (up to 30%, depending on the incident light intensity and the hour of the day). Reduced light intensity increased the dry mass of each of the plant components studied. Consequently, the total dry mass of shaded plants was significantly greater than that of controls at the end of the growing season. However, the diurnal trend in the level of photosynthesis (per unit of leaf area) of shaded plants was similar to the controls in August, but lower in September. As the growing season proceeded, reduced photosynthetic rates, thinner mesophyll and larger specific leaf area in the shaded plants indicated that leaf development had adapted to shaded conditions throughout the growing season. It is suggested that increased growth of shaded plants was caused by a higher initial relative growth rate and a greater whole-plant photosynthesis. Shading consistently reduced transpiration over the season, therefore improving water use efficiency of shaded leaves. Our results suggest that a moderate reduction in light intensity can be a useful method for improving growth and saving water in hot and dry environments.     

温度对赤拟谷盗爬行和起飞活动的影响

在不同温度下研究了赤拟谷盗Tribolium castaneum(Herbst)在固体物面、设定粮面、温度均匀的粮(小麦)柱和具有温度梯度粮柱内爬行扩散速度、起飞温度等.主要结果为:赤拟谷盗在17℃开始有爬行为,25℃开始有飞行行为,在15～25℃时水平爬行速度和15 ～ 20℃时竖直运动速度与温度呈显著正相关,在无障...     

Efficacy of chlorfenapyr against adult Tribolium castaneum exposed on concrete: effects of exposure interval, concentration and the presence of a food source after exposure

Chlorfenapyr, an insecticidal pyrrole, was applied to concrete arenas at concentrations of 1.1, 0.825, 0.55, and 0.275 g of active ingredient [AI]/m². Adult Tribolium castaneum (Herbst), the red flour beetle, were exposed for 2, 4, or 8 h at each concentration, then removed and held either with or without food (wheat flour) for 7 days. Survival was assessed when the beetles were removed from the exposure arenas and daily during the post-exposure period. In the presence of food, survival was high regardless of concentration and the day on which post-treatment survival was assessed, but survival did decrease as the exposure period increased from 4 to 8 h. When the beetles were not given food after exposure, survival at each concentration and exposure period declined during the 1-week post-exposure assessments. This pattern of decrease could be described by linear and non-linear equations. Results show the presence of food material greatly compromised effectiveness of the insecticide, and emphasize the importance of cleaning and sanitation in conjunction with insecticide treatments.     

The influence of the ability to disperse on generation length and population size in the flour beetle, Tribolium castaneum

Abstract.

• 1 In Tribolium castaneum Herbst, in which dispersal is genetically determined, it is possible to select for strains that are characterized by high and low dispersal, High dispersal (HD) beetles are better adapted than low dispersal (LD) beetles for colonization, as can be seen from differences that exist between the two groups with regard to several life-history parameters.
• 2 Comparisons were made between the dynamics of seventy-two HD and seventy-two LD populations. Generation length in HD populations was significantly shorter than in LD populations. After 9¹/₂ weeks, in open treatments (from which dispersal away from the set was allowed), HD populations had more beetles than LD populations, whereas in closed treatments (from which dispersal away from the set was not allowed) the opposite was true.
• 3 These findings may explain the maintenance of the genetic variability of dispersal behaviour in natural populations of T.castmeurn.

     

Characterization of the Tribolium Deformed ortholog and its ability to directly regulate Deformed target genes in the rescue of a Drosophila Deformed null mutant

 We have analyzed the Tribolium castaneum ortholog of the Drosophila homeotic gene Deformed (Dfd) and determined its expression pattern during embryogenesis in this beetle. Tc Deformed (Tc Dfd) is expressed in the blastoderm and the condensing germ rudiment in a region that gives rise to gnathal segments. During germ band extension Tc Dfd is expressed in the mandibular and maxillary segments, their appendages, and the dorsal ridge. Comparison of insect Dfd protein sequences reveals several highly conserved regions. To determine whether common molecular features reflect conserved regulatory functions we used the Gal4 system to express the Tribolium protein in Drosophila embryos. When Tc Dfd is expressed throughout embryonic ectoderm under the control of P69B, the beetle protein autoregulates the endogenous Dfd gene. In addition, the Drosophila proboscipedia gene (a normal target of Dfd) is ectopically activated in the antennal and thoracic segments. We also compared the ability of the beetle and fly proteins to rescue defects in Dfd ^– mutants by expressing each throughout the embryonic during embryogenesis. Both proteins rescued Dfd ^– defects to the same extent in that they each restore the development of mouth hooks and cirri, as well as cause gain-of-function abnormalities of posterior mouth parts. As before, pb was ectopically activated in the antennal segment. This is the first demonstration of the ability of a heterologous homeotic selector protein to directly regulate a target gene independent of an endogenous Drosophila autoregulatory loop. Received: 11 December 1998 / Accepted: 8 March 1999     

不同杀虫剂处理对赤拟谷盗P450基因诱导表达特性影响

害虫细胞色素P450基因可被杀虫剂迅速诱导,然而当前对不同杀虫剂处理下赤拟谷盗P450基因诱导表达特性的研究较少。本研究首先通过序列比对选取了来自不同家族的8个赤拟谷盗P450基因CYP4G7、CYP4Q4、CYP4BR3、CYP12H1、CYP6BK11、CYP9D4、CYP9Z5和CYP345A1,然后采用四种不同杀虫剂氯氰菊酯、氟氯氰菊酯、氯菊酯和吡虫啉对赤拟谷盗20 d幼虫进行生物测定,再根据生测结果以四个药剂亚致死剂量分别处理幼虫,并采用荧光定量PCR分析8个P450基因的表达特性。结果表明,CYP4G7和CYP345A1可以分别被氯氰菊酯(分别上调1.97倍和2.06倍)、氟氯氰菊酯(2.00倍和2.03倍)和氯菊酯(1.73倍和1.81倍)显著诱导,而CYP4BR3和CYP345A1可以被吡虫啉(分别上调1.99倍和1.93倍)显著诱导。本研究结果表明赤拟谷盗P450基因的显著诱导与基因家族类型以及农药品种有关。     

Suppression of the stored-product insect Tribolium confusum by Xylocoris flavipes and Amphibolus venator

Abstract:  We evaluated the suppression of the confused flour beetle, Tribolium confusum , by the anthocorid bug Xylocoris flavipes and the reduviid bug Amphibolus venator . Four treatments were tested: X. flavipes adults, A. venator adults, X. flavipes adults and A. venator adults released, and control (no predators). After 25 days, X. flavipes alone showed 96.9% suppression of T. confusum , A. venator alone showed 76.2% suppression and both the predatory bugs together showed 95.6% suppression. The rates of loss of whole-wheat flour as an index of damage caused by T. confusum were 2.7%, 6.4%, 3.6% and 11.7% in X. flavipes adults, A. venator adults, X. flavipes adults and A. venator adults released, and control respectively. Furthermore, A. venator attacked X. flavipes adults but not X. flavipes nymphs. The possibility of using both X. flavipes and A. venator against T. confusum is discussed.     

Biochemical effects of sublethal doses of cypermethrin on the sixth-instar larvae of Tribolium castaneum (Herbst.)

Effects of sublethal doses ie, 2, 4, 10, and 20 ppm of cypermethrin, were studied on the sixth-instar larvae of Tribolium castaneum (Herbst.). Of all the biochemical parameters tested, the free amino acids and cholesterol content and the activity of amylase were found to be the most sensitive components. Glutamate pyruvate transaminase activity was elevated at all doses except 2 ppm. The activities of alkaline phosphatase and glutamate oxaloacetate transaminase and glucose content were raised significantly at doses of 10 and 20 ppm. Acid phosphatase activity and the soluble protein content increased at a dose of 20 ppm. Total lipid and triglycerides, however, decreased significantly at this sublethal dose. Other biochemical parameters, such as cholinesterase and lactate dehydrogenase activities and the total protein, urea, glycogen, DNA, and RNA contents, were not significantly affected by exposure to different doses of cypermethrin.