首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Swimming dynamics of the giant Australian cuttlefish, Sepia apama, were investigated using swimtunnel respirometry. Relationships between jet pressure, fin frequency, swimming speed and oxygen consumption were defined. Laboratory calibration of swimming parameters is necessary to allow estimates of swimming costs in the field.

Jet pressure was the best predictor of oxygen consumption with an averaged equation of MO2 = 722 (jet pressure) + 107 r2 = 0.51. Individually, fin frequency and jet pressure correlated highly to swimming speed, but due to the complicated usage of finning and jetting, the correlation between swimming speed and oxygen consumption was weaker. Cuttlefish were not optimal swimtunnel subjects and could not swim at high speeds for extended periods. At 15°C and a swimming speed of 0.06 m s-1, the gross cost of transport was calculated to be 10.1 kg-1 m -1, with a net cost of 4.1 kg-1 m-1.  相似文献   

2.
Sperm displacement behavior of cuttlefish (Sepia esculenta) was observed in a tank. Before ejaculation, male cuttlefish used their arms III to scrape out sperm masses attached to the buccal membranes of females. The removed sperm mass debris was directly visible and countable. Active sperm were present within the removed sperm debris, implying that the aim of this behavior is to remove competing male sperm. However, many sperm masses remained on the female buccal membrane even after the removal behavior, showing that sperm removal in S. esculenta is incomplete. The duration of sperm removal (an indicator of male investment in that process) was unaffected by the body sizes of mated pair, the duration of spermatangia placement at the current mating (for the hypothesis that the sperm removal serves to creat attachment space of spermatophores), or the estimated amount of sperm masses deposited from previous matings. Moreover, male S. esculenta performed sperm removal regardless of whether the last male to mate with the partner was himself, suggesting males remove not only the sperm of rivals but also their own. Although the number of removed sperm masses increased with the time spent on removal of sperm, male cuttlefish may shorten the duration of sperm removal to avoid the risk of mating interruption. We conclude that this time restriction would likely influence the degree of partial sperm removal in S. esculenta. A digital video image relating to the article is available at .This revised version was published online in April 2005 with corrections in the abstract.  相似文献   

3.
Hatchlings cuttlefish were reared in the laboratory from hatching until 30 days old, fed with live shrimp, frozen shrimp or fish oil-enriched frozen shrimp. Survival of cuttlefish fed with oil-enriched frozen shrimp was better than in animals receiving live shrimp. However, there was no difference with cuttlefish fed with frozen shrimp, even if survival of those receiving oil-enriched frozen shrimp was always higher all along the experiment. Lower survival in animals fed with live shrimp represented the problem of using such food and confirms the necessity to elaborate an artificial food. Utilization of artemia was detrimental to growth and induced low values of instantaneous growth rate (IGR) and conversion rate even after feeding cuttlefish with shrimp. Nevertheless, growth parameters evolutions generally corresponded to those observed by other researchers. The profile noticed at the end of the experiment is typically observed when cuttlefish acquire their adult digestive system. Main differences were observed between groups fed with live shrimp or oil-enriched frozen shrimp. Enrichment did not induce same growth as in cuttlefish receiving live prey. However, at 20 and 25 days after hatching (DAH), in cuttlefish fed with oil-enriched frozen shrimp, ration was lower for the same growth than in other groups.These data showed capacity of juvenile cuttlefish to adjust their digestive enzyme activities according to the diet and the stage of development. Indeed, chymotrypsin was strongly influenced by enrichment, while other enzymes showed difference between live and frozen preys. Trypsin exhibited regulation by diet after 20 DAH. Freezing seemed to delay development as acid phosphatases, characteristic of first stages of cuttlefish, had lower activity in cuttlefish fed with live shrimp at 10 DAH. Moreover, influence of the stage of development was strong as activities between 20 and 30 DAH were different in all groups. This was in relation with evolution of the digestive system. These data illustrated the difficulty to elaborate optimal diet as digestive system evolves.  相似文献   

4.
A laboratory calibration study was undertaken with juvenile Sepia officinalis (80-85 g initial wet weight) to investigate the effects of different food rations and different starving intervals on RNA/dry weight (DW) ratios and RNA/DNA ratios in cephalopod mantle muscle at two different temperatures. The digestive gland index was also used as an additional indicator of recent growth. High food rations and low temperature went along with high RNA/DW ratios and high RNA/DNA ratios. Starving resulted in a linear decline in growth performance and a concomitant decrease in RNA/DW and RNA/DNA ratio, with RNA/DNA ratios representing the growth data better. RNA/DNA ratios decreased faster at higher temperatures. A fluorimetric assay for nucleic acid analysis was optimized for cephalopod mantle tissues and yielded reproducible RNA/DNA ratios with a relative variance below 10%. Thus, it may be possible to use this estimator of recently encountered feeding regime for the evaluation of mortality rates of early teuthid paralarvae to eventually support stock management. Also, log relative digestive gland weight showed a strong relationship with starving time, but, surprisingly, not with temperature. Data from the two temperatures analyzed could be combined to form a common regression line of relative digestive gland index with starving time. This indicator for recent growth might be especially suitable for large specimens with a well-developed digestive gland.  相似文献   

5.
The objective of this study was to examine the impact of crowding (stocking density) on food consumption and growth of juvenile Sepia officinalis reared at 17 and 25 °C. Two groups of 75 cuttlefish each were reared in closed seawater systems with water temperatures of 17 and 25 °C. Each group was subdivided into two treatments (three replicates per treatment): low-density (equivalent to 100 Sepia m−2) and high-density (equivalent to 400 Sepia m−2). Food consumption was measured daily and live wet body weight (g) was measured weekly over a 5-week study. The 25 °C treatment resulted in significantly higher growth rates and food consumption compared to the 17 °C treatment. Stocking density had no statistically significant effect on food consumption, gross growth efficiency (GGE), or weight at either temperature. However, the high-density treatments had slightly lower GGE values overall and growth in weight at 25 °C was slightly but consistently lower in the high-density treatment suggesting that stocking densities of 400 Sepia m−2 may be approaching levels that impact feeding and growth.  相似文献   

6.
The purpose of this study was to establish a bioassay from isolated digestive gland cells of the cuttlefish Sepia officinalis in order to observe the effect of heavy metals on digestive enzyme activities. Digestive cells were isolated using a pronase enzyme that was removed by several washings of the cell suspension. Cell viability was tested by the MTT assay (3-4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium) and microscopic analysis. The results showed that isolated digestive cells could be maintained 24 h with preservation of whole digestive functionality, measured in terms of MTT test. In fact, the viability was maintained at a high level during 24 h and the intra- and extracellular digestive enzyme activities became stabilised rapidly. Furthermore, suspension cells responded to calcium ionophore and 8-Bromo-cAMP by an unspecific secretion of extracellular digestive enzyme, trypsin, which demonstrated that isolated digestive cells were functional. Using the bioassay, ecotoxicological studies showed that heavy metals could have effects on digestive enzyme activities after 24 h of an incubation time of the metal with the cells. In fact, zinc and silver affected trypsin and/or cathepsins specific activity of the cells. On the contrary, copper had no effect on digestive enzyme activities. Zinc, which is a trace element in all living animals, generated two different responses of cathepsins and cell viability. At a low concentration (0.02 μM), it increased viability and cathepsins specific activity, whereas at a high concentration (0.02 mM), zinc inhibited the cathepsins specific activity with an inhibition of cathepsins. For silver, whatever the tested concentration (0.02 mM or 0.02 μM), it has no impact on digestive gland isolated cell viability. Nevertheless, heavy metal induced high disturbance of enzymatic systems.  相似文献   

7.
We tested the utility of acoustic tri-axial acceleration transmitters in combination with ethogram and respirometry studies to quantify the activity patterns and field metabolic rates of free-swimming bonefish (Albula vulpes) in the coastal waters of Eleuthera, The Bahamas. Bonefish were found to exhibit relatively low activity levels in the field with no evidence of diel patterns or inter-sexual variation. Low activity levels reported by the accelerometers reflected low swimming speeds and intermittent swimming behaviours (i.e., swim-then-drift) that maximized energy efficiency. Such behaviours were also observed when conducting ethograms on bonefish held in a large field mesocosm. Laboratory derived standard metabolic rates and maximum metabolic rates during recovery from exercise were combined with acceleration transmitter calibrations to determine that individual bonefish typically operate at between 40 and 60% of their estimated metabolic scope in the field. However, occasionally acceleration values in the field were indicative of high intensity bursting activity that exhausted the majority of their estimated metabolic scope (0.7% of all field observations exceed 90% of estimated metabolic scope). Data gathered in this study provide a critical starting point for the development of a bioenergetics model for bonefish which will ultimately lend clues into how fish make a living in tropical tidal flats environments. Given that this paper is one of the first to use transmitters rather than archival loggers to collect data on tri-axial acceleration on fish, we also discuss the opportunities and limitations of using this new technology for marine fisheries research.  相似文献   

8.
Alloteuthis is a group of small, slender loliginid squids of minor fisheries importance. There are three nominal Alloteuthis species—A. media (Linnaeus), A. subulata (Lamarck) and A. africana Adam. Two of these species (A. media and A. subulata) have largely overlapping ranges in the Mediterranean and northeastern Atlantic, while A. africana is found along the west coast of Africa. Despite the low level of species diversity, Alloteuthis taxonomy and systematics are confused, and assignment of specimens to species can be difficult. To clarify Alloteuthis systematics, we gathered morphometric data and DNA sequence data from two mitochondrial loci and a nuclear locus from Alloteuthis specimens collected from several localities. Analyses of the morphometric data suggest that head width is the main variable allowing separation of A. africana from the other two species, and central club sucker size separates A. media from A. subulata. One easily diagnosable character often used to distinguish Alloteuthis species—relative fin length—appears to be of little taxonomic value. Only three specimens assignable to A. subulata both morphologically and genetically were found, all from the Adriatic; possible reasons for this apparent rarity are discussed. Gene tree parsimony and coalescent-based methods were used to estimate species relationships from the molecular data, and both supported a sister-species relationship between A. media and A. subulata. Analyses of molecular variation (AMOVA's) revealed significant genetic differentiation between Atlantic and Mediterranean A. media. This study highlights the importance of 1) sampling multiple individuals, locations and loci for species-level phylogenetic studies, 2) using morphometric analyses to reveal taxonomically meaningful morphological characters and 3) accounting for the stochastic nature of the coalescent process when estimating species phylogenies for closely related taxa.  相似文献   

9.
Ambrosia beetles (Coleoptera: Scolytinae) are associated with strictly entomochoric and mutualistic fungi. We studied the mycobiota associated with Scolytodes unipunctatus, ambrosia beetles that infest Cecropia trees in Central America. Isolates were characterized using morphology and rDNA sequences (ITS region, LSU, and SSU rDNA). Four species are described here: Raffaelea scolytodis sp. nov. (Ophiostomatales), Gondwanamyces scolytodis sp. nov., Custingophora cecropiae sp. nov., and Graphium sp. (Microascales). The genus Custingophora is emended to include Knoxdaviesia anamorphs of Gondwanamyces based on uniformity of DNA sequences and phenotype.  相似文献   

10.
The squids Uroteuthis (Photololigo) edulis and Uroteuthis (Photololigo) chinensis (family Loliginidae) are commercially important fishery species in many coastal regions of Asia. The morphologies of these two squids are very similar, and identification based on morphology has been inadequate. The occurrence of cryptic species in the family Loliginidae has been reported. The widely distributed U. (P.) chinensis and U. (P.) edulis are believed to comprise several cryptic species. In this study, the taxonomic status of the two species in East Asia was elucidated by morphological and genetic analyses. Analysis of U. (P.) chinensis from Hong Kong and Xiamen (China) and U. (P.) edulis from Yamaguchi (Japan) and Shanghai (China) was performed in order to determine the effectiveness of different morphometric variables in discriminating between the two species. Multivariate analysis of 27 morphometric indices revealed no new morphological characters for the taxonomic identification of the two taxa, which can be distinguished by the teeth shape and number on arm sucker rings, and the percentage of hectocotylized part of left arm IV of males. The morphometric differences between U. (P.) edulis individuals from the two localities is most probably due to differences in the maturity stages of the sampled individuals between the two localities. Genetic analysis based on the mitochondrial COI and 16S rRNA genes revealed a high divergence of 15.5% and 7.5% respectively, indicating that U. (P.) edulis and U. (P.) chinensis are distinct species.  相似文献   

11.
The dynamics of the protozoan parasite Marteilia refringens was studied in Thau lagoon, an important French shellfish site, for 1 year in three potential hosts: the Mediterranean mussel Mytilus galloprovincialis (Mytiliidae), the grooved carpet shell Ruditapes decussatus (Veneriidae) and the copepod Paracartia grani (Acartiidae). Parasite DNA was detected by PCR in R. decussatus. In situ hybridisation showed necrotic cells of M. refringens in the digestive epithelia of some R. decussatus suggesting the non-involvement of this species in the parasite life cycle. In contrast, the detection of M. refringens in mussels using PCR appeared bimodal with two peaks in spring and autumn. Histological observations of PCR-positive mussels revealed the presence of different parasite stages including mature sporangia in spring and autumn. These results suggest that the parasite has two cycles per year in the Thau lagoon and that mussels release parasites into the water column during these two periods. Moreover, PCR detection of the parasite in the copepodid stages of P. grani between June and November supports the hypothesis of the transmission of the parasite from mussels to copepods and conversely. In situ hybridisation performed on copepodites showed labeling in some sections. Unusual M. refringens cells were observed in the digestive tract and the gonad from the third copepodid stage, suggesting that the parasite could infect a copepod by ingestion and be released through the gonad. This hypothesis is supported by the PCR detection of parasite DNA in copepod eggs from PCR-positive females, which suggests that eggs could contribute to the parasite spreading in the water and could allow overwintering of M. refringens. Finally, in order to understand the interactions between mussels and copepods, mussel retention efficiency (number of copepods retained by a mussel) was measured for all P. grani developmental stages. Results showed that all copepod stages could contribute to the transmission of the parasite, especially eggs and nauplii which were retained by up to 90%.  相似文献   

12.
The ultrastructure of septa and septum-associated septal pore caps are important taxonomic markers in the Agaricomycotina (Basidiomycota, Fungi). The septal pore caps covering the typical basidiomycetous dolipore septum are divided into three main phenotypically recognized morphotypes: vesicular-tubular (including the vesicular, sacculate, tubular, ampulliform, and globular morphotypes), imperforate, and perforate. Until recently, the septal pore cap-type reflected the higher-order relationships within the Agaricomycotina. However, the new classification of Fungi resulted in many changes including revision of existing and addition of new orders. Therefore, the septal pore cap ultrastructure of more than 325 species as reported in literature was related to this new classification. In addition, the septal pore cap ultrastructures of Rickenella fibula and Cantharellus formosus were examined by transmission electron microscopy. Both fungi have dolipore septa associated with perforate septal pore caps. These results combined with data from the literature show that the septal pore cap-type within orders of the Agaricomycotina is generally monomorphic, except for the Cantharellales and Hymenochaetales.It appears from the fungal phylogeny combined with the septal pore cap ultrastructure that the vesicular-tubular and the imperforate type both may have arisen from endoplasmic reticulum. Thereafter, the imperforate type eventually gave rise to the perforate septal pore cap-type.  相似文献   

13.
Torrubiella is a genus of arthropod-pathogenic fungi that primarily attacks spiders and scale insects. Based on the morphology of the perithecia, asci, and ascospores, it is classified in Clavicipitaceae s. lat. (Hypocreales), and is considered a close relative of Cordyceps s. 1., which was recently reclassified into three families (Clavicipitaceae s. str., Cordycipitaceae, Ophiocordycipitaceae) and four genera (Cordyceps s. str, Elaphocordyceps, Metacordyceps, and Ophiocordyceps). Torrubiella is distinguished morphologically from Cordyceps s. lat. mainly by the production of superficial perithecia and the absence of a well-developed stipitate stroma. To test and refine evolutionary hypotheses regarding the placement of Torrubiella and its relationship to Cordyceps s. lat., a multi-gene phylogeny was constructed by conducting ML and Bayesian analyses. The monophyly of Torrubiella was rejected by these analyses with species of the genus present in Clavicipitaceae, Cordycipitaceae, and Ophiocordycipitaceae, and often intermixed among species of Cordyceps s. lat. The morphological characters traditionally used to define the genus are, therefore, not phylogenetically informative, with the stipitate stromata being gained and/or lost several times among clavicipitaceous fungi. Two new genera (Conoideocrella, Orbiocrella) are proposed to accommodate two separate lineages of torrubielloid fungi in the Clavicipitaceae s. str. In addition, one species is reclassified in Cordyceps s. str. and three are reclassified in Ophiocordyceps. The phylogenetic importance of anamorphic genera, host affiliation, and stipitate stromata is discussed.  相似文献   

14.
Two new gregarines in the recently erected genus Psychodiella (formerly Ascogregarina), Psychodiella sergenti n. sp. and Psychodiella tobbi n. sp., are described based on morphology and life cycle observations conducted on larvae and adults of their natural hosts, the sand flies Phlebotomus sergenti and Phlebotomus tobbi, respectively. The phylogenetic analyses inferred from small subunit ribosomal DNA (SSU rDNA) sequences indicate the monophyly of newly described species with Psychodiella chagasi. Ps. sergenti n. sp. and Ps. tobbi n. sp. significantly differ from each other in the life cycle and in the size of life stages. The sexual development of Ps. sergenti n. sp. (syzygy, formation of gametocysts and oocysts) takes place exclusively in blood-fed Ph. sergenti females, while the sexual development of Ps. tobbi n. sp. takes place also in males and unfed females of Ph. tobbi. The susceptibility of Phlebotomus perniciosus, Phlebotomus papatasi, Ph. sergenti, Ph. tobbi, and Phlebotomus arabicus to both gregarines was examined by exposing 1st instar larvae to parasite oocysts. High host specificity was observed, as both gregarines were able to fully develop and complete regularly the life cycle only in their natural hosts. Both gregarines are considered as serious pathogens in laboratory-reared colonies of Old World sand flies.  相似文献   

15.
The distribution of Hohorstiella lata, Colpocephalum turbinatum, Campanulotes bidentatus compar, and Comlumbicola columbae on domestic pigeons were determined. Each species laid its eggs on a different part of the body but all fed on the fluffy part of the body feathers. H. lata also fed on blood, and C. turbinatum on its own eggs and nymphs. Reduction of the efficiency of preening led to an increase in the number of lice and more widespread distribution of nymphs and adults but not to a rapid change in the distribution of eggs. It is suggested that preening has played a major selective role, and that the morphological and behavioural adaptions of the lice are to ensure that they and their eggs survive this type of predation.  相似文献   

16.
Xylanase Z of Clostridium thermocellum exists as a complex in the cellulosome with N-terminus feruloyl esterase, a carbohydrate binding module (CBM6) and a dockerin domain. To study the role of the binding modules on the activity of XynZ, different variants with the CBM6 attached to the catalytic domain at its C-terminal (XynZ-CB) and N-terminal (XynZ-BC), and the CBM22 attached at N-terminus (XynZ-B′C) were expressed in Escherichia coli at levels around 30% of the total cell proteins. The activities of XynZ-BC, XynZ-CB and XynZ-B′C were 4200, 4180 and 20,700 U μM−1 against birchwood xylan, respectively. Substrate binding studies showed that in case of XynZ-BC and XynZ-CB the substrate birchwood xylan remaining unbound were 51 and 52%, respectively, whereas in the case of XynZ-B′C the substrate remaining unbound was 39% under the assay conditions used. The molecular docking studies showed that the binding site of CBM22 in XynZ-B′C is more exposed and thus available for substrate binding as compared to the tunnel shape binding pocket produced in XynZ-BC and thus hindering the substrate binding. The substrate binding data for the two constructs are in agreement with this explanation.  相似文献   

17.
Floral initiation and development of Hedysarum varium, Onobrychis melanotricha and Alhagi persarum was studied using epi-illumination light-microscopy techniques. The studied species belong to the tribe Hedysareae of the inverted repeat loss clade (IRLC clade), which is characterized by missing the large inverted repeat in the chloroplast genome. The main aim of our study was to determine developmental bases for similarities and differences among the three taxa and to verify the position of Alhagi relative to other genera of the IRLC clade. According to our observations, bracteoles are missing in Onobrychis melanotricha, but are present in the other two species. All three species share unidirectional sepal initiation starting with a median abaxial sepal and bidirectional petal initiation. Stamen initiation is unidirectional in all except in the outer stamen whorl of Hedysarum varium, where it is bidirectional. An important ontogenetic feature in O. melanotricha is the existence of five common primordia, which give rise to petal and stamen primordia. Although in H. varium and O. melanotricha common primordia are observed at some stages in floral organ initiations, in Alhagi all organs are initiated separately. Moreover, overlap in time of floral organs initiation occurs in H. varium and O. melanotricha, but not in A. persarum. The carpel initiates concurrently with the petal primordia in all. It might be presumed that Alhagi is primitive in relation to the other studied Hedysareae taxa, due to the presence of bracteoles, the absence of common primordia, and the lack of overlap in time of different organ initiations.  相似文献   

18.
Octopus vulgaris is a cephalopod species in several oceans and commonly caught by artisanal and industrial fisheries. In Brazil, O. vulgaris populations are mainly distributed along the southern coast and have been subjected to intensive fishing during recent years. Despite the importance of this marine resource, no genetic study has been carried out to examine genetic differences among populations along the coast of Brazil. In this study, 343 individuals collected by commercial vessels were genotyped at six microsatellite loci to investigate the genetic differences in O. vulgaris populations along the southern coast of Brazil. Genetic structure and levels of differentiation among sampling sites were estimated via a genotype assignment test and F-statistics. Our results indicate that the O. vulgaris stock consists of four genetic populations with an overall significant analogous FSTCT = 0.10710, P < 0.05) value. The genetic diversity was high with an observed heterozygosity of Ho = 0.987. The negative values of FIS found for most of the loci examined suggested a possible bottleneck process. These findings are important for further steps toward more sustainable octopus fisheries, so that this marine resource can be preserved for long-term utilization.  相似文献   

19.
20.
In recent years there has been growing interest in analyzing the geographical variations between populations of different Phlebotomus spp. by comparing the sequences of various genes. However, little is known about the genetic structure of Phlebotomus ariasi. In this study, we were able to sequence a fragment of the mitochondrial Cyt b gene in 133 sandflies morphologically identified as P. ariasi and proceeding from a wide geographical range covering 35 locations in 11 different regions from five countries. The intra-specific diversity of P. ariasi is high, with 45 haplotypes differing from each other by one to 26 bases and they are distributed in two mitochondrial lineages, one limited geographically to Algeria and the other widely dispersed across Mediterranean countries. The Algerian lineage is characterized by having 13 fixed polymorphisms and is made up of one sole haplotype. The European/Moroccan P. ariasi lineage is characterized by being made up of a great diversity of haplotypes (44) which display some geographical structuring. This could be one of the multiple factors involved in the epidemiological heterogeneity of the foci of leishmaniasis. Phlebotomus chadlii is the sister group of European/Moroccan P. ariasi. The separation of the Algerian haplotype, H45, from the rest of the specimens, European/Moroccan P. ariasi and P. chadlii, is well supported by the bootstrap analysis.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号