粳稻品种幼苗耐冷性比较研究

利用人工模拟低温胁迫的方法,研究了３个日本粳稻品种日本晴、金南风和福光以及２个台湾粳稻品种台竹１５７、加南２０的苗期耐冷性,并以当地推广高产籼稻品种特三矮２号作对照。从对株高、主茎叶片数、地上部干物重、死苗率等形态性状的调查和叶绿素含量、电解质外渗率等生理性状测定的结果显示,日本晴、金南风、福光和台竹１５７苗期的耐冷性较强,加南２０的耐冷性较弱,但比特三矮２号的耐冷性略强。这为防止早稻烂秧死苗而开     

Diapause and seasonal life cycle strategy in the house spider, Achaearanea tepidariorum (Araneae, Theridiidae)

Abstract In order to elucidate the mechanism regulating its seasonal life cycle, the photoperiodic response of Achaearanea tepidariorum has been analysed. Nymphal development was faster in long-day and slower in short-day photoperiods. The combined action of low temperature, poor food supply and short daylength induced diapause at an earlier developmental stage than short days alone. Thus, photoperiod is a primary factor inducing nymphal diapause, but the diapausing instar is influenced by both temperature and food supply. Hibernating nymphs became unresponsive to photoperiod in late December. After hibernation, however, sensitivity was restored and the nymphs remained sensitive to photoperiod throughout their life. This spider could also enter an imaginal or reproductive diapause. Photoperiod was again a primary inducing factor and temperature modified the photoperiodic response to some extent. The induction of the reproductive diapause was almost temperature-compensated whereas development was not. So the involvement of a photoperiodic counter system was suggested. Irrespective of whether the nymph had experienced diapause or not, the imaginal diapause was induced in response to a short-day photoperiod after adult moult. Based on these observations, the seasonal life cycle and the adaptive significance of nymphal and imaginal diapause are discussed.     

Expression of Target Antigen for Epstein-Barr Virus-Specific Cytotoxic T Cells on BJAB Cells Freshly Infected with EBV

The target antigen for Epstein-Barr virus (EBV)-specific cytotoxic T cells (Tc) was expressed on BJAB cells exposed to the B95-8 strain of EBV for at least one hour. Ultraviolet-light (UV)-irradiated noninfectious B95-8 virus also induced the target antigen on BJAB cells. Cold target competition tests suggested that the target antigen expressed on EBV-infected BJAB cells was distinct from the lymphocyte-detected membrane antigen (LYDMA) which was also recognized by the EBV-specific Tc and expressed on autologous EBV-transformed lymphoblastoid cell line (LCL) cells. Neither of these target antigens for EBV-specific Tc was detected on the surface of EBV-genome positive BJAB cells which had been kept in a long-term culture after EBV-infection. Thus, the virion antigen, especially the EBV-membrane antigen (MA), is a possible candidate for the target antigen expressed on EBV-infected BJAB cells. Lysis of EBV-infected BJAB cells was inhibited by target cell treatment with anti-β2 microglobulin (anti-β2M) antibody and induction of the effector Tc was dependent on the donor individual. These resalts suggested the possibility that the Tc recognizing EBV-infected BJAB cells are restricted by the major histocompatibility complex (MHC).     

Flying distance of frass kicked by the grasshopper Atractomorpha lata and factors affecting the flying distance

Adults of the grasshopper Atractomorpha lata use a hind leg kick to project their frass a considerable distance from themselves. To clarify the defecation behavior quantitatively and collect basic information that aids in clarification of the adaptive significance of this behavior, we measured the flying distance of kicked frass and examined the factors affecting the flying distance in adult A. lata. Males and females kicked their frass an average of 252 and 487 mm away, respectively. This represented more than ten times the body length or 100 times the length of the frass pellet for either sex. Only sex affected the flying distance of frass. There were sexual differences in hind‐femur length (females longer than males), volume of frass pellet (females larger than males) and ratio of diameter to length of frass pellet (RFP; larger in males than in females). The flying distance appears to be affected by the femur length, volume of frass pellet and RFP when data of both males and females were combined for analysis. However, none of these effects were observed when testing the effects within each sex. These results suggest that the sex difference in the flying distance does not result from the sex difference in femur length, volume of frass pellet or RFP. Because A. lata kicked their frass far away in both sexes, the frass‐kicking behavior might give benefit common to both males and females.     

Thermal biology of a colour‐dimorphic snake,Elaphe quadrivirgata,in a montane forest: do melanistic snakes enjoy thermal advantages?

The adaptive significance of colour polymorphisms in animals has received extensive scientific attention. In snakes, a generally accepted hypothesis is that melanistic individuals enjoy thermal advantages compared to normal coloured individuals. Elaphe quadrivirgata on Yakushima Island exhibits a distinct melanistic/striped colour dimorphism. To test this hypothesis, the thermal biology of free‐ranging E. quadrivirgata was investigated using temperature‐sensitive radio transmitters. The thermal quality of habitats was also evaluated using physical models of the snake. In addition, the species' set‐point range (T_set) was estimated using a laboratory experiment. In July, thermal environments appear to be benign because snakes were able to maintain their body temperature (T_b) within T_set from the midday to evening by using average thermal habitats. By contrast, later months of the year were severe in thermoregulation, and snakes had difficulty maintaining their T_b within T_set by using average thermal habitats. There were no significant intermorph differences in thermoregulation indices in any months, whereas slight differences were detected in hourly comparisons. Most of these comparisons indicated active and precise thermoregulation (with respect to T_set) in striped individuals by using thermally favourable but rare microhabitats such as forest gap. Thus, the obtained values do not support the prediction that melanistic individuals are precise thermoregulators. Yet, melanistic individuals do modify their thermoregulation strategy with respect to the available thermal environments in contrast to striped individuals. Together with the fact that body heating is slower in striped individuals than in melanistic individuals under experimental conditions, it is concluded that melanistic individuals have the potential to enjoy thermal advantages but that this might be of no practical use in terms of T_b in the wild because of the greater thermoregulatory efforts of striped individuals, and because melanistic individuals may use forest gap rarely due to conspicuousness to visually orientated predators under the exposed habitat. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92 , 309–322.     

农杆菌介导的玉米大斑病菌转化

采用玉米大斑病菌Exserohilum turcicum的无性菌丝作受体,建立了农杆菌Agrobacterium tumefaciens介导的转化方法。采用的载体为 pUR5750, 携有来源于质粒pAN71的潮霉素抗性选择标记。PCR分析表明T-DNA 插入到E. turcicum基因组中。     

Adult eclosion rhythm of the Indian meal moth Plodia interpunctella: response to various thermocycles with different means and amplitudes

In addition to photoperiod, thermoperiod (or thermocycle) might be an important Zeitgeber for entraining the circadian oscillator controlling adult eclosion rhythm in the Indian meal moth Plodia interpunctella Hübner (Lepidoptera: Pyralidae). This is confirmed by exposing larvae receiving diapause‐preventing treatments to various thermocycles with different means and amplitudes of temperature. The thermocycles investigated in the present study are TC 8 : 16 h, TC 12 : 12 h, TC 16 : 8 h and TC 20 : 4 h, where T and C represent thermophase (30 °C) and cryophase (20 °C), respectively. For all thermocycles, the peak of adult eclosion rhythm occurs at around the mid‐thermophase. This indicates that the larvae use both ‘temperature‐rise’ and ‘temperature‐fall’ signals to adjust the eclosion phase in each thermocycle. The absence (DD) or presence (LL) of light affects this time‐keeping system slightly under the given thermocycle. The rhythmic adult eclosion noted after exposure of larvae to 30 °C DD for 14 days is recorded in the thermocycles (TC 12 : 12 h, DD; mean temperature = 25 °C) with different amplitudes of 27.5/22.5 °C, 26.5/23.5 °C and 25.5/24.5 °C. The peak in adult eclosion advances in time as the amplitude of the temperature cycle decreases. In the temperature cycle of 25.5/24.5 °C, a peak occurs at the end of the cryophase, 2 h before the temperature‐rise. The adult eclosion rhythm is also observed under various thermocycles (TC 12 : 12 h, DD) consisting of different temperature levels (30 to 20 °C) with different amplitudes. It is found that the temporal position of the peak advances significantly when the amplitude of the thermocycle becomes lower.