基于线粒体COⅠ和NADH-6基因分子检测的中日家蚕和野桑蚕亲缘关系的研究

为了进一步明确家蚕和野桑蚕的亲缘关系,收集了中国和日本的一些家蚕和野桑蚕品种资源,提取了家蚕和野桑蚕的总mRNA,通过RT-PCR克隆了家蚕和野桑蚕线粒体DNA (mtDNA)的细胞色素氧化酶亚基1基因(cytochrome oxidase subunit 1 gene, COⅠ)和NADH-6基因,并制备探针进行了DIG-RFLP检测。结果表明,中国和日本的家蚕与中国野桑蚕的COⅠ和NADH-6基因的DIG-RFLP的分子多态性相同,但与日本野桑蚕存在差异。此结果从线粒体水平证实了中国和日本的家蚕都起源于中国野桑蚕,而不是起源于日本的野桑蚕。     

The effect of illumination on the electrical conductance of rhodopsin solutions

An apparatus was constructed in order to record continuously and simultaneously changes in extinction and electrical conductance of rhodopsin solutions. With this apparatus, changes in electrical conductance on exposing rhodopsin to light were investigated. On illumination solutions of rhodopsin revealed a conductance change so long as they preserved their photosensitivity. The conductance change begins almost immediately upon illumination and is almost proportional to the amount of rhodopsin decomposed, continuing until rhodopsin is converted to indicator yellow. Near pH 7 the conductance is apt to increase slightly, while it decreases considerably outside the range of pH 6–9, being accompanied by a pH change towards neutrality. The conductance change is regarded as an essential property of rhodopsin, because it occurs in aqueous suspension as well as in digitonin solution; it may be caused by hydrogen or hydroxyl ions and some other conductive substances. It is also noteworthy that the petroleum ether-soluble component of the rod outer segments—presumably the lipide—tends to increase the conductance change. In suspensions of rod outer segments and retinal homogenates, the conductance increases on illumination irrespective of pH: this may be due to secondary reactions following the photic reaction of rhodopsin. We shall discuss the significance of the conductance change in relation to the initiation of visual excitation.     

Distribution of Membrane-Associated Calcium in Fertilized Sea Urchin Eggs during Mitosis*

The distribution of membrane-associated calcium in dividing sea urchin eggs was examined with chlortetracycline as a fluorescent chelate probe. The fluorescence of bound chlortetracycline in fertilized eggs was initially evenly distributed, but began to gather around the nucleus in prophase, and formed a dumb-bell shaped condensation enclosing the mitotic apparatus by metaphase. During anaphase and telophase, the fluorescence was observed in kinetochore-to-pole regions of the spindle, with little fluorescence in the interkinetochore region. The astral regions showed intense fluorescence. The distribution of the chlortetracycline-fluorescence coincided with that of ER-like membranes seen in electron micrographs. The distribution of the fluorescence was obscure and the birefringence of spindles disappeared on perfusion on perfusion of the cells in metaphase with 1 mM tetracaine, which is known to displace membrane-bound calcium. These results suggest that intracellular free calcium ions are sequestered in the membrane system associated with the mitotic apparatus during mitosis.     

Larval morphology and phylogenetic position of Horelophopsis hanseni Satô et Yoshitomi (Coleoptera,Hydrophilidae, Horelophopsinae)

The subfamily Horelophopsinae was originally proposed as one of the earliest diverging clades of Hydrophilidae (s.s.), but its phylogenetic placement has never been tested. We describe the larva of Horelophopsis hanseni Satô et Yoshitomi, 2004 of the Horelophopsinae. Larval data are based on larval specimens collected together with adults, and unambiguously associated with them by means of DNA barcoding. We perform an analysis testing the phylogenetic position of H. hanseni based on larval and adult morphological characters. Horelophopsis hanseni is unambiguously placed within the hydrophilid subfamily Hydrophilinae and its close relationships to the genus Agraphydrus Régimbart, 1903 (Hydrophilinae, Acidocerini) is recognized. The results suggest that the subfamily Horelophopsinae is unlikely to be a basal taxon of Hydrophilidae, as originally suggested.     

Female-biased sex ratio in a wild bruchid seed-predator, Kytorhinus sharpianus. I. Larval competition and other factors

Abstract.

• 1 A wild bruchid seed-predator, Kytorhinus sharpianus, has a complex life cycle consisting of bi- and trivoltinism on a wild leguminous plant, Sophola flavescens. Observations of adults showed significant female-biased sex ratios (from 1:2 to 1:6) for nine generations over 4 years.
• 2 To investigate the potential effects of larval competition on the sex ratio, we altered the number of hatched eggs per seed and counted emergent males and females under laboratory conditions. Although only one adult could emerge per seed, the ratio of the females that emerged increased with the number of hatched eggs per seed. However, the sex ratio was not significantly different from 1:1 in the case of one hatched egg per seed.
• 3 We dissected seeds bearing two hatched eggs at regular intervals, and classified the surviving and the dead larvae according to their developmental stage. Over time, one larva within each seed always survived, while the other larva died from the second to fourth instar before the seed resource became exhausted.
• 4 In order to study the effects of the difference in the stages of two larvae in a seed on the emergence sex ratio, we manipulated intervals between the first and second ovipositions in the laboratory. As the difference in developmental stages of the two larvae increased, the closer to 1:1 the emergence sex ratio became.
• 5 Field observations, however, showed that about 60% of infested seeds were bored by only one K.sharpianus larva. This suggests that female dominance in larval competition within a seed may be relatively unimportant in causing the female-biased sex ratio in the field.

     

Choanoflagellates (Sarcomastigophora, Protozoa) from the Coastal Waters of Taiwan and Japan. I. Three New Species

Three new acanthoecidaean species collected from the coastal waters of Taiwan and Japan are described: Acanthocorbis camarensis n. sp. resembles Acanthocorbis unguiculata in lorica morphology, but differs in having regularly arranged longitudinal and transverse costae at the anterior lorica chamber, and in lacking a nail at the apical end of anterior spine; Diaphanoeca spiralifurca n. sp. is characterized by the spiral arrangement of the costal strips in the posterior half of the lorica chamber and is closely related to Diaphanoeca grandis; Stephanoeca supracostata n. sp. is closely related to Stephanoeca elegans, but differs in having an additional transverse costa at the anterior lorica chamber.     

A Canopy Photosynthesis Model for the Dynamics of Size Structure and Self-thinning in Plant Populations

A dynamic model for growth and mortality of individual plantsin a stand was developed, based on the process of canopy photosynthesis,and assuming an allometric relationship between plant heightand weight, i.e. allocation growth pattern of plant height andstem diameter. Functions G(t, x), for the mean growth rate ofindividuals of size x at time t, and M(t,x), for the mortalityrate of individuals of size x at time t, were developed fromthis model and used in simulations. The dynamics of size structurewere simulated, combining the continuity equation model, a simpleversion of the diffusion model, with these functions. Simulationsreproduced several well-documented phenomena: (1) size variabilityin terms of coefficient of variation and skewness of plant weightincreases at first with stand development and then stabilisesor decreases with an onset of intensive self-thinning; (2) duringthe course of self-thinning, there is a power relationship betweendensity and biomass per unit ground area, irrespective of theinitial density and of the allocation-growth pattern in termsof the allometric parameter relating plant height and weight.The following were further shown by simulation: (a) competitionbetween individuals in a crowded stand is never completely one-sidedbut always asymmetrically two-sided, even though competitionis only for light; (b) plants of ‘height-growth’type exhibit a greater asymmetry in competition than plantsof ‘diameter-growth’ type, (c) the effect of competitionon the growth of individuals in a crowded stand converges toa stationary state, even when the stand structure still changesgreatly. All of these theoretical results can explain recentempirical results obtained from several natural plant communities.Finally, a new, general functional form for G(t, x) in a crowdedstand is proposed based on these theoretical results, insteadof a priori or empirical growth and competition functions. Canopy photosynthesis, competition mode, continuity equation, self-thinning, simulation, size distribution     

Effects of gamma irradiation on the life stages of yellow flower thrips, Frankliniella schultzei (Trybom) (Thysanoptera: Thripidae)

Irradiation at a minimum absorbed dose of 250 Grays (Gy) has been approved by the USDA as a quarantine treatment for certain fruits in Hawaii to control four species of tephritid fruit flies. Subsequent research must determine whether this dose is sufficient to control other quarantine pests, such as mealybugs, thrips, mites, beetles, moths, and scale insects, on other commodities with export potential that are approved for irradiation treatment for fruit flies. This study demonstrated that irradiation at 250 Gy caused non‐emergence of eggs and pupae, failure of larval development, and sterility of adults of yellow flower thrips, Frankliniella schultzei (Trybom). Adults were the most resistant stage tested, with 100% mortality at 57, 36 and 30 days post‐treatment for the 250, 350 and 400 Gy treatments, respectively. Untreated adults survived up to 66 days. After receiving an irradiation dose of 250 Gy, no one‐ to two‐day old eggs hatched successfully, while 3–4‐day old eggs hatched but did not develop beyond the larval stage. Of the controls, 96.0% of 1–2‐day old eggs and 75.9% of the 3–4‐day old eggs hatched and survived through pupation. No first or second instar larvae treated with a target dose of 250 Gy were able to pupate. When pupae were irradiated at 250 Gy, 37% emerged as adults and all were sterile compared to 88.3% emergence of controls.