Enzymatic and mitochondrial responses to 5 months of aerial exposure in the slender lungfish Protopterus dolloi

Mitochondrial respiration and activities of key metabolic enzymes from liver and white skeletal muscle were compared between control aquatic slender lungfish Protopterus dolloi , and those exposed to air for 5 months. Activities of citrate synthase, glycogen phosphorylase, phosphofructokinase and pyruvate kinase in liver were not affected by air-exposure. In muscle, air-exposure reduced citrate synthase and pyruvate kinase activities (relative to tissue wet mass) by 63 and 50%, respectively. Liver carnitine palmitoyl transferase activity (relative to mitochondrial protein) decreased by half following air-exposure, but there was no change in muscle. In mitochondria isolated from muscle, state 3 and state 4 respiration were reduced by 74 and 89%, respectively following air-exposure, but liver mitochondria were not affected. In liver, air-exposure increased activities of ornithine-urea cycle enzymes including glutamine synthase, carbamoyl-phosphate synthase III and arginase, by 1·9- to 4·2-fold. Carbamoyl-phosphate synthase III activity could not be detected in muscle, indicating that urea is not synthesized in this tissue. These data suggest that skeletal muscle metabolism is downregulated in air-exposure, conserving energy and protein during a period when the animals cannot forage. In contrast, ATP production capacities in the liver are maintained, and this may permit expensive urea biosynthesis to continue during aerial exposure.     

Hot and steady: Elevated temperatures do not enhance muscle disuse atrophy during prolonged aestivation in the ectotherm Cyclorana alboguttata

Animals that undergo prolonged dormancy experience minimal muscle disuse atrophy (MDA) compared to animals subjected to artificial immobilisation over shorter timeframes. An association between oxidative stress and MDA suggests that metabolic depression presumably affords dormant animals some protection against muscle disuse. Because aerobic metabolism is temperature sensitive, we proposed that MDA in dormant (aestivating) ectotherms would be enhanced at elevated temperatures. In the green‐striped burrowing frog, Cyclorana alboguttata, the thermal sensitivity of skeletal muscle metabolic rate is muscle‐specific. We proposed that the degree of atrophy experienced during aestivation would correlate with the thermal sensitivity of muscle metabolic rate such that muscles with a relatively high metabolic rate at high temperatures would experience more disuse atrophy. To test this hypothesis, we examined the effect of temperature and aestivation on the extent of MDA in two functionally different muscles: the M. gastrocnemius (jumping muscle) and M. iliofibularis (non‐jumping muscle), in C. alboguttata aestivating at 24 or 30°C for 6 months. We compared a range of morphological parameters from muscle cross‐sections stained with succinic dehydrogenase to show that muscle‐specific patterns of disuse atrophy were consistent with the relative rates of oxygen consumption of those muscle types. However, despite muscle‐specific differences in thermal sensitivity of metabolic rate, aestivation temperature did not influence the extent of atrophy in either muscle. Our results suggest that the muscles of frogs aestivating at high temperatures are defended against additional atrophy ensuring protection of muscle function during long periods of immobilisation. J. Morphol., 2013. © 2012 Wiley Periodicals, Inc.     

Age Composition, Growth and Reproductive Biology of the Salamanderfish Lepidogalaxias salamandroides: A Re-examination

This study has determined the age and size compositions, growth rate and reproductive biology of Lepidogalaxias salamandroides using data for fish of known sex and age and the monthly trends exhibited by various gonadal variables, including the sizes and stages of the oocytes. The results resolve conflicting conclusions drawn by other workers concerning certain aspects of the biology of this freshwater species and expands our knowledge of this teleost. Our results are based on data derived from samples collected from small, ephemeral acidic pools in south-western Australia in 22 consecutive months. Although ca. 78% of the fish caught belonged to the 0+ age class, substantial numbers of the 1+ and 2+ age classes and some 3+ and 4+ fish were caught. Spawning occurs between late May and late August, with peak activity in late July and early August. During the first year of life, growth is initially rapid, but then ceases in the weeks immediately prior to and during the period when the habitat becomes dry and fish aestivate, before recommencing in autumn as the pools again become filled with water. The growth coefficient (K) in the von Bertalanffy growth equation was lower for females (0.63) than males (1.28), reflecting the greater growth undergone by females after the first year of life. Maturity was attained by ca. 28% of the females and ca. 26% of the males that reached the end of their first year of life and by all fish that reached the end of subsequent years of life. The L₅₀s for females and males at first maturity were 43.2 and 38.6mm TL, respectively. The mean fecundity was only 82.4, reflecting a combination of a small body size and a relatively large egg (diameter=1.8mm). Lepidogalaxias salamandroides is a multiple spawner, which increases the chances of some eggs and newly-hatched embryos encountering a period of favourable environmental conditions during the spawning period, which is characterised by bouts of heavy rainfall. The ratio of females to males was essentially parity in the 0+ and 1+ age classes and in all age classes collectively. When testes commence maturing for the first time, the anal fin of males starts to become modified to form a structure that facilitates the transfer of sperm to the female, and it remains modified throughout the rest of life.     

大猿叶虫生活史的研究

大猿叶虫Colaphellus bowringi是江西山区十字花科蔬菜上的重要食叶害虫,以成虫在土中越夏和越冬。由于成虫滞育期的差异,该虫的化性显示了明显的种内变异。有些个体隔年繁殖;有些个体是一化性的,仅在春季或秋季繁殖1代;有些个体是二化性的,春季和秋季各繁殖1代;有些个体是多化性的,春季1代,秋季2～3代。因此,大猿叶虫在田间一年可发生4代。在春季,滞育成虫于2月底至4月初陆续出土繁殖;在秋季,滞育成虫于8月中旬至10月初陆续出土繁殖。春季羽化的成虫于4月底至6月上旬陆续入土越夏,秋季羽化的成虫于9月中旬至12月底陆续入土越冬。大猿叶虫一生能交配多次,大多数雌虫的产卵期超过1个月,最长达67天。平均每雌产卵量：春季世代为644粒,秋季世代为963粒,最高达1.950粒。各虫态的发育历期：在15～30℃间,卵为13.78～3.14天,幼虫为22.83～6.95天,蛹为12.10～3.18天。发育阈值温度：卵为10.7℃,幼虫为8.8℃,蛹为9.6℃。非滞育成虫的寿命约为1～2个月,滞育成虫的寿命为5～38个月。滞育成虫均入土蛰伏,在土中的蛰伏深度为9～31 cm 。     

夏眠对刺参(Apostichopus japonicus(Selenka))能量收支的影响

夏眠是刺参最重要的生理特征;水温升高是其夏眠的主要诱发因子,而夏眠的临界温度与刺参体重密切相关。为揭示刺参夏眠对其能量利用对策的影响,测定了2种体重规格（134.0±13.5）g和(73.6±2.2）g刺参在10、15、20、25 ℃和30 ℃ 5个温度梯度下的能量收支。结果表明,温度和体重及其交互作用对刺参能量的摄入均有显著影响;而温度是影响其摄食能分配的主要因素。研究发现,刺参在非夏眠期、夏眠临界期和完全夏眠期的能量利用对策有所不同：在非夏眠期,刺参摄食能支出的最大组分是粪便能,占摄食能的比例超过50%,其次为呼吸耗能,占19.8%~39.4%,而生长能和排泄能占的比例较小,分别为5.7%~10.7%和2.9%~3.7%;在夏眠临界温度下,呼吸和排泄耗能占摄食能的比例均显著增大（分别为88.3%和13.6%）,而生长能所占比例降为负值（-55.3%）,刺参表现为负生长;而在夏眠期,刺参的摄食能和排粪能为零,为维持其基本生理活动,不得不动用以往贮存于体内的能量,消耗于呼吸和排泄等生理过程,供维持生命之用。总之,从能量生物学的角度看,夏眠的主要生态学意义在于刺参长时间处于相对高温环境,进而导致摄食受阻条件下的一种能量节约方式。     

Laboratory studies on aestivation in the cabbage root fly (Delia radicum)

Laboratory experiments at 16°–30°C showed that the cabbage root fly can only be induced into aestivation during the early part of the pupal stage. The relationship between the percentage of pupae entering aestivation (y) and the average daily temperature (T) was the same under both constant and alternating temperatures. The percentage of pupae entering aestivation at a particular temperature was given by y=13T–255. An additional 13% of the pupae entered aestivation for each degree rise between 20° and 27°C. There was no constant period of arrested development following the induction of aestivation. Aestivating pupae started to develop into flies as soon as the temperature fell below 20°C. The reinduction of aestivation occurred more readily than the initial induction. Insect survival was not reduced after a month of aestivation. The effects of aestivation on forecasting the time of the second (summer) generation of flies are discussed.

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Étude au laboratoire de l'estivation de la mouche du Chou (Delia radicum)

Résumé Au laboratoire, à 10°–30°C, l'induction de l'estivation ne peut être obtenue qu'avec des pupes formées depuis peu.Le rapport pourcentage de pupes entrant en estivation (y) température journalière moyenne (T) a été le même, que la température soit constante ou alternée. La relation entre la température et ce pourcentage est donnée par y=13 T–255. Le pourcentage de pupes entrant en estivation a augmenté de 13% pour chaque élévation d'un degré entre 20° et 27°C. L'estivation une fois induite, la période d'arrêt de développement n'est pas constante. Dès que la température est devenue inférieure à 20°C, la formation d'imagos a commencé dans les pupes en estivation. Une nouvelle estivation a été plus facile à provoquer que l'estivation initiale. Le taux de survie des insectes n'avait pas diminué après un mois d'estivation. La discussion examine l'utilisation des conséquences de l'estivation dans la prédiction de la seconde génération d'adultes: génération d'été.

     

Larval aestivation and direct development as alternative strategies in the speckled wood butterfly, Pararge aegeria, in Sweden

ABSTRACT.

• 1 Sweden has two disjunct populations of the speckled wood butterfly, Pararge aegeria L. The southern population has two generations per year but the central Swedish population is univoltine. When rearing larvae from central Sweden under normal photoperiodic conditions but at temperatures slightly above the ambient, 42% of the larvae developed directly and produced a second generation of adults the same summer. The egg—larval development time of the directly developing individuals was about 40 days, whereas that of the individuals developing along the univoltine pathway was about 100 days.
• 2 Larvae of the central Swedish population normally aestivate during part of the summer even though abundant food is available. In the closely related Lasiommata petropolitana F., which is the only Swedish satyrid that overwinters in the pupal stage besides P.aegeria, larvae do not aestivate, indicating that there does not seem to be any obligatory association between pupal hibernation and larval aestivation.
• 3 Development rates of aestivating and directly developing P.aegeria are equal up to the third larval instar. During the third and fourth instars, however, the development rate of aestivating individuals is retarded and females also have an additional fifth instar.
• 4 Since the central Swedish P.aegeria have the capacity to develop directly, and the southern Swedish ones have the capacity to aestivate, the evidence indicates that the outcome of the cost/benefit balance of univoltine versus bivoltine development differs between the two areas.

     

Multiple role of temperature during insect diapause: a review

The review emphasizes that there are multiple pathways to diapause completion. The programmed course of events is modified by environmental cues. Often chilling is not a prerequisite for the completion of hibernation diapause (examples tabulated). Diapause completion progresses well at intermediate or high temperatures, sometimes it is even stimulated by high or increasing temperature. Low temperatures are important, as they (1) conserve metabolic reserves, (2) prevent resumption of post-diapause morphogenesis and thus synchronize the life-cycle, (3) represent contrast to the later increase in temperature. Diapause consists of phases with different prerequisites. There is a principal difference between diapause development and photoperiodic activation as indicated by the subsequent physiological condition of insects.     

Internal fertilization in Lepidogalaxias salamandroides Mees (Pisces: Lepidogalaxiidae)

The gonads of Lepidogalaxias salamandroides are structurally distinctive. A duct, the surface of which is ciliated, is located on the ventral surface of each ovary and may be a modification of the ovarian tunica. The testes are small and the majority of the testicular structure functions as a sperm storage area. Secondary requisite sex characters are present in the male and the function of a modified scale sheath in copulation is unique among teleosts. Fertilization is internal and a viscous mucus mass secreted during copulation may serve as a copulatory plug. It is postulated that internal fertilization within this species has arisen as a response to sperm competition.     

Internal fertilization in Lepidogalaxias salamandroides Mees (Pisces: Lepidogalaxiidae)

The gonads of Lepidogalaxias salamandroides are structurally distinctive. A duct, the surface of which is ciliated, is located on the ventral surface of each ovary and may be a modification of the ovarian tunica. The testes are small and the majority of the testicular structure functions as a sperm storage area. Secondary requisite sex characters are present in the male and the function of a modified scale sheath in copulation is unique among teleosts. Fertilization is internal and a viscous mucus mass secreted during copulation may serve as a copulatory plug. It is postulated that internal fertilization within this species has arisen as a response to sperm competition.