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851.
Effects of salinity on endogenous rhythm of the Manila clam, Ruditapes philippinarum (Bivalvia: Veneridae) 总被引:1,自引:0,他引:1
The Manila clam Ruditapes philippinarum, an intertidal bivalve, was exposed to different salinity regimes (from 31.0–31.7‰ down to 20‰, 15‰, 10‰, 5‰), and the endogenous
rhythm in its oxygen consumption was studied using an automatic intermittent-flow respirometer. When exposed to salinities
reduced from 31.5‰ to 20‰ and 15‰ under otherwise constant conditions, the clams recovered a clear endogenous circatidal rhythm
in their oxygen-consumption rate after having dampened periods of 12 h and 48 h, respectively. At salinities less than 10‰,
however, the oxygen-consumption rate was depressed greatly at the beginning of the experiment for about 36 h and then increased
to a level higher than normal, but the rhythm of oxygen consumption was not recovered. The results of this study indicate
that the Manila clam, a euryhaline organism, cannot maintain a normal metabolic activity at a salinity lower than 15‰. All
clams were dead after exposure at a salinity of 5‰ for 7 days.
Received: 28 February 2000 / Accepted: 26 August 2000 相似文献
852.
853.
D. Kim T. Okamoto T. Oda K. Tachibana K.S. Lee A. Ishimatsu Y. Matsuyama T. Honjo T. Muramatsu 《Marine Biology》2001,139(4):625-632
Although the ichthyotoxic mechanism of Chattonella marina is still unknown, several lines of evidence suggest that the reactive oxygen species (ROS), such as superoxide anion (O2-), hydrogen peroxide (H2O2), and hydroxyl radical (·OH), produced by C. marina are involved in the mortality of fish exposed to this flagellate. Recently, we found that the cell-free supernatant prepared from C. marina, which is considered to contain the glycocalyx, showed NADPH-dependent O2- generation. In this study, we prepared antiserum against the crude glycocalyx of C. marina. Using indirect immunofluorescence, it was confirmed that the antiserum specifically reacted with C. marina cells. In addition to C. marina, the antiserum also reacted with other raphidophycean flagellates such as Heterosigma akashiwo, Olisthodiscus luteus, and Fibrocapsa japonica, whereas no reactivity was observed against six other flagellate species tested. These results suggest that raphidophycean flagellates have common epitopes recognized by the antiserum. Interestingly, immunohistochemical analysis of paraformaldehyde-fixed gill lamellae from yellowtail exposed to C. marina revealed that the antiserum stained the surface of gill lamellae, while no such staining pattern was observed in control gill lamellae. These results suggest that the glycocalyx may be discharged when C. marina cells are inhaled into the fishes' mouths and then come into contact with the gill surface. Based on the present results, together with our previous findings, we propose that continuous accumulation of the discharged glycocalyx on the gill surface occurs during C. marina exposure, which may be responsible for the ROS-mediated severe gill tissue damage leading to fish death. 相似文献
854.
One-day-old anarchistic (selected for successful worker reproduction) and wild-type honey-bee workers were introduced into queenright colonies of honey-bees of two treatments. In treatment 1, all eggs and larvae were offspring of queens from an anarchistic line. In treatment 2, all eggs and larvae were offspring of wild-type queens. In both treatments, adult workers were wild type. This experimental arrangement was used to test the importance of larval genotype on ovary activation in young adult workers. After 12 days, the introduced bees were dissected to determine the frequency of ovary activation. In those colonies provided with wild-type brood, 0% of introduced wild-type bees and 16% of anarchistic bees had activated ovaries. In those colonies provided with anarchistic brood, 13% of introduced wild-type bees and 41% of anarchistic bees had activated ovaries. These results strongly support the hypothesis that selection for high levels of worker reproduction in anarchistic stocks has reduced the amount or composition of brood pheromones produced by larvae that normally signal workers to refrain from reproduction. They also suggest that anarchistic workers have a higher threshold for these signals than wild-type bees. 相似文献
855.
Claudia Voelckel Tamara Krügel Klaus Gase Nadja Heidrich Nicole M. van Dam Robert Winz Ian T. Baldwin 《Chemoecology》2001,11(3):121-126
856.
Abstract: Peregrine Falcons ( Falco peregrinus ) of seven subspecies from four continents were bred in captivity, and approximately 1173 of their progeny were released in the midwestern United States and adjacent regions of Ontario and Manitoba in an attempt to replace the original population that was extirpated by chlorinated hydrocarbon poisoning in the 1950s. We analyzed the success of individuals of the different subspecies introduced to the Midwest. Five of the seven subspecies released have contributed to the current breeding population. Subspecies of breeding Peregrine Falcons were equally represented when breeding birds of high productivity were compared with less prolific breeders. The subspecific makeup of the breeding population did not differ significantly from that of the released population, suggesting that adaptability in this species was sufficient to override genetic differences between subspecies. Peregrines of widely different genetic stocks have thrived after release, making substantial genetic contributions to the new population. 相似文献
857.
858.
Simultaneous hermaphroditism with outcrossing, a previously unconfirmed sexual system in decapod crustaceans, is documented
in the shrimp Lysmata wurdemanni (Gibbes), using time-lapse video observations on mating in pairs of “female-phase” (FP) individuals. Copulations between
FPs resulted in successful spawning and development of embryos. However, female-phase hermaphrodites maintained in isolation
were unable to self-fertilize spawned eggs. All smaller individuals possessed characters typical of caridean males, including
male gonopores, appendices masculinae, ejaculatory ducts, and cincinnuli on the first pleopods. However, the gonad of these
male-phase (MP) individuals was an ovotestis with an undeveloped ovarian portion. FPs, which spawn eggs and incubate embryos,
also had male gonopores and an ovotestis terminating in ejaculatory ducts containing sperm. In FPs, male pleopod characters
were absent or reduced, and a female incubatory character, expanded pleopod flanges, showed a greater relative size. Smaller
size classes of the population were composed only of MPs while larger size classes consisted of both MPs and FPs. “Transitionals,”
individuals with MP characters but an ovotestis containing vitellogenic oocytes, were rare and overlapped completely in size
with FP and larger MP individuals. It is suggested that not all MPs transform into FP hermaphrodites. Social interactions
may mediate MP change into FP hermaphrodites in L. wurdemanni. The social system of L. wurdemanni and other Lysmata spp. may determine the exact form of the sexual system in these species.
Received: 26 October 1997 / Accepted: 21 April 1998 相似文献
859.
Anthelia glauca Lamarck, 1816 is a gonochoric, external-brooding soft coral found in KwaZulu-Natal. It is reproductively active in the summer
months. The development of gametes produced in late summer is arrested in winter. Several stages of gametes are found at the
base of the polyps, and female polyps produce several cycles of larvae over an extended breeding period of 4 to 5 months.
Larvae are brooded in a unique pharyngeal brooding pouch not yet described in other coral species. The brood pouch consists
of an expansion of the pharynx with constrictions proximal and distal to the embryos and larvae. Our data suggest that egg
transfer and fertilization occur at full moon and the mature larvae are released after new moon. Zooxanthellae are absent
in A. glauca oocytes, but zooxanthella infestation commences at the immature larval stage.
Received: 15 July 1997 / Accepted: 12 March 1998 相似文献
860.
Chattonella marina, a raphidophycean flagellate, is a highly toxic red tide phytoplankton which causes severe damage to fish farming. Recent
studies demonstrated that Chattonella spp. continuously release superoxide anions (O2
−) while they are living. Heterosigma akashiwo, another raphidophycean flagellate, also produces O2
−. In the present study, we found that lectins such as concanavalin A (Con A), wheat germ agglutinin (WGA), and castor bean
hemagglutinin (CBH) stimulated C. marina and H. akashiwo to generate enhanced amounts of O2
− in a concentration-dependent manner. The lectin-specific sugars potently inhibited the lectin-induced increase of O2
− production, suggesting that the effects of lectins are mediated mainly through the interaction of these lectins with carbohydrate
moiety present on the flagellate cell surface. In contrast to the potent ability of native Con A (tetravalent), succinylated
Con A (divalent) showed only a slight stimulative effect on these flagellates. O2
− production was totally inhibited by treatment with proteinase K for 30 min, without affecting the viabilities of flagellates.
These results suggest that cell-surface redox enzymes may be involved in O2
− production, and such enzymes are responsible for the lectin-stimulation.
Received: 21 August 1997 / Accepted: 8 January 1998 相似文献