Thermal biology of flight in a butterfly: genotype,flight metabolism,and environmental conditions

Knowledge of the effects of thermal conditions on animal movement and dispersal is necessary for a mechanistic understanding of the consequences of climate change and habitat fragmentation. In particular, the flight of ectothermic insects such as small butterflies is greatly influenced by ambient temperature. Here, variation in body temperature during flight is investigated in an ecological model species, the Glanville fritillary butterfly (Melitaea cinxia). Attention is paid on the effects of flight metabolism, genotypes at candidate loci, and environmental conditions. Measurements were made under a natural range of conditions using infrared thermal imaging. Heating of flight muscles by flight metabolism has been presumed to be negligible in small butterflies. However, the results demonstrate that Glanville fritillary males with high flight metabolic rate maintain elevated body temperature better during flight than males with a low rate of flight metabolism. This effect is likely to have a significant influence on the dispersal performance and fitness of butterflies and demonstrates the possible importance of intraspecific physiological variation on dispersal in other similar ectothermic insects. The results also suggest that individuals having an advantage in low ambient temperatures can be susceptible to overheating at high temperatures. Further, tolerance of high temperatures may be important for flight performance, as indicated by an association of heat‐shock protein (Hsp70) genotype with flight metabolic rate and body temperature at takeoff. The dynamics of body temperature at flight and factors affecting it also differed significantly between female and male butterflies, indicating that thermal dynamics are governed by different mechanisms in the two sexes. This study contributes to knowledge about factors affecting intraspecific variation in dispersal‐related thermal performance in butterflies and other insects. Such information is needed for predictive models of the evolution of dispersal in the face of habitat fragmentation and climate change.     

Effects of dehydration rate on physiological responses and survival after rehydration in larvae of the anhydrobiotic chironomid

Strategies to combat desiccation are critical for organisms living in arid and semi-arid areas. Larvae of the Australian chironomid Paraborniella tonnoiri resist desiccation by reducing water loss. In contrast, larvae of the African species Polypedilum vanderplanki can withstand almost complete dehydration, referred to as anhydrobiosis. For successful anhydrobiosis, the dehydration rate of P. vanderplanki larvae has to be controlled. Here, we desiccated larvae by exposing them to different drying regimes, each progressing from high to low relative humidity, and examined survival after rehydration. In larvae of P. vanderplanki, reactions following desiccation can be categorized as follows: (I) no recovery at all (direct death), (II) dying by unrepairable damages after rehydration (delayed death), and (III) full recovery (successful anhydrobiosis). Initial conditions of desiccation severely affected survival following rehydration, i.e. P. vanderplanki preferred 100% relative humidity where body water content decreased slightly. In subsequent conditions, unfavorable dehydration rate, such as more than 0.7 mg water lost per day, resulted in markedly decreased survival rate of rehydrated larvae. Slow dehydration may be required for the synthesis and distribution of essential molecules for anhydrobiosis. Larvae desiccated at or above maximum tolerable rates sometimes showed temporary recovery but died soon after.     

籼稻的抗冷性与亲本的关系

四个籼稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）品种幼苗经１℃黑暗或光照２５０ μｍ ｏｌ·ｍ － ２·ｓ－ １处理后,抗冷的“桂山矮选３”比不抗冷的“青华６ 号”幼苗存活率高,其子代是以“桂山矮选３”为母本的比“青华６ 号”为母本的存活率较高。抽穗期剑叶经光照低温处理１２、２４ 和３６ ｈ 后,光合作用是“桂山矮选３”和以“桂山矮选３”为母本的子代比“青华６ 号”和以“青华６ 号”为母本的子代下降较少。呼吸作用是前者比后者在处理１２ ｈ 时有明显升高现象。荧光参数Ｆｖ／Ｆｏ和Ｆｖ／Ｆｍ比值在处理２４ ｈ 时前者比后者下降明显,但在常温下恢复则是前者比后者明显较快。自然低温（寒露风）对叶绿素荧光的影响亦有相似的规律。对水稻后代的抗冷性倾向于母本进行了讨论     

紫羊茅重金属抗性和敏感品种中类金属硫蛋白基因的鉴定及表达初探

重金属对生命机体的作用具有双重性。一方面,作为多数辅酶的辅助因子对细胞的正常代谢必不可少;另一方面,当重金属超过一定的浓度时对细胞有较大的毒性。在长期的进化过程中,生物可能形成一种调节细胞内重金属浓度的机制。这种机制在动物和真菌中被认为同金属硫蛋白(metallothionein,MT)的作用密切相关。植物中也存在类似的与重金属结合的低分子量蛋白(heavy metal binding pep-tide)。最近对拟南芥菜和水稻中类金属硫蛋白(MT-like)基因的研究证实其作用与动物MT相似。紫羊茅品种“Merlin”是一种从锌铅矿区的重金属污染地采集的单子叶草种,对镉和铜的抗性都较高,分别达到50mg/L和30mg/L,而5mg/L Cd~(2 )或2mg/L Cu~(2 )便可抑制敏感品种“S59”的正常生长。目前     

Subcellular Distribution and Chemical Forms of Cadmium in the Medicine Food Homology Plant <i>Platycodon grandiflorum</i> (Jacq.) A.DC.

Although Platycodon grandiflorum (Jacq.) A.DC. is a renowned medicine food homology plant, reports of excessive cadmium (Cd) levels are common, which affects its safety for clinical use and food consumption. To enable its Cd levels to be regulated or reduced, it is necessary to first elucidate the mechanism of Cd uptake and accumulation in the plant, in addition to its detoxification mechanisms. This present study used inductively couple plasma-mass-spectrometry to analyze the subcellular distribution and chemical forms of Cd in different tissues of P. grandiflorum. The experimental results showed that Cd was mainly accumulated in the roots [predominantly in the cell wall (50.96%–61.42%)], and it was found primarily in hypomobile and hypotoxic forms. The proportion of Cd in the soluble fraction increased after Cd exposure, and the proportion of insoluble phosphate Cd and oxalate Cd increased in roots and leaves, with a higher increase in oxalate Cd. Therefore, it is likely that root retention mechanisms, cell wall deposition, vacuole sequestration, and the formation of low mobility and low toxicity forms are tolerance strategies for Cd detoxification used by P. grandiflorum. The results of this study provide a theoretical grounding for the study of Cd accumulation and detoxification mechanisms in P. grandiflorum, and they can be used as a reference for developing Cd limits and standards for other medicine food homology plants.     

Resilience to Freezing in the Vegetative Cells of the Microalga Lobosphaera incisa (Trebouxiophyceae,Chlorophyta)

The chlorophyte microalga Lobosphaera incisa was isolated from the snowy slopes of Mt. Tateyama in Japan. This microalga stores exceptionally high amounts of the omega-6 LC-PUFA arachidonic acid in triacylglycerols, and therefore represents a potent photosynthetic source for this essential LC-PUFA. Assuming that freezing tolerance may play a role in adaptation of L. incisa to specific ecological niches, we examined the capability of L. incisa to tolerate extreme sub-zero temperatures. We report here, that the vegetative cells of L. incisa survived freezing at −20°C and −80°C (over 1 month), without cryoprotective agents or prior treatments. Cells successfully recovered upon thawing and proliferated under optimal growth conditions (25°C). However, cells frozen at −80°C showed better recovery and lower cellular ROS generation upon thawing, compared to those preserved at −20°C. Photosynthetic yield of PSII, estimated by F_v/F_m, temporarily decreased at day 1 post freezing and resumed to the original level at day 3. Interestingly, the thawed algal cultures produced a higher level of chlorophylls, exceeding the control culture. The polar metabolome of the vegetative cells comprised a range of compatible solutes, dominated by glutamate, sucrose, and proline. We posit that the presence of endogenous cryoprotectants, a rigid multilayer cell wall, the high LC-PUFA content in membrane lipids, and putative cold-responsive proteins may contribute to the retention of functionality upon recovery from the frozen state, and therefore for the survival under cryospheric conditions. From the applied perspective, this beneficial property holds promise for the cryopreservation of starter cultures for research and commercial purposes.     

Accumulation and detoxification of cadmium in <Emphasis Type="Italic">Brassica pekinensis</Emphasis> and <Emphasis Type="Italic">B. chinensis</Emphasis>

The effect of excessive Cd on the growth and metal uptake by leafy vegetables Brassica chinensis L. (cv. Wuyueman) and Brassica pekinensis (Lour.) Rupr. (cv. Qingyan 87-114) were studied in hydroponic solution culture. The Cd concentration higher than 10 μM significantly decreased the root elongation and leaf chlorophyll contents of both plant species. The shoots of B. pekinensis had significantly higher concentrations of total and water-soluble Cd than B. chinensis. The roots of both species accumulated more Cd than the shoots in all the Cd treatments. Most of the Cd in the roots was found in the cell walls. The shoot/root ratio of Cd concentrations in B. pekinensis was always greater than that in B. chinensis. But, the concentration and proportion of Cd in the cell walls in B. chinensis were higher than that in B. pekinensis. Cadmium treatments also increased the concentrations of total non-protein thiols (NPT) in the shoots of the both species. A significant correlation was found between the concentrations of soluble Cd and NPT in plant shoots.