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1.
The present study was conducted to determine the age relationships in lengths and weights of Boops boops (Linneaus, 1756) in Izmir Bay, central Aegean Sea. A total of 932 specimens (503 females and 429 males) were caught by gillnet, trammel net and a combination thereof on a monthly sampling basis from November 2008 through October 2009. Total length and weight of sampled fish ranged from 11.3 to 27.9 cm and from 12.2 to 261.7 g, with a mean of 19.6 cm and 82.7 g, respectively. Length‐weight relationships for all individuals were described by the parameters = 0.0050, = 3.237 and r² = 0.956. The von Bertalanffy growth curve fitted to the lengths‐at‐age provided parameters of L = 29.87 cm = 0.243 and to = ?0.98 for males and L = 30.79 cm, = 0.239 and to = ?0.90 for females. Based on otolith readings, age determinations varied from 1 to 5 years. Maximum age was 5 years in age group 2, with 29.84 and 37.97% for males and females, respectively. The overall 1 : 1.17 sex ratio of males to females was significantly biased toward females (P < 0.05). There was no statistical difference in the mean condition factor (P > 0.05), with a value of 1.028 for the entire population. The growth performance index (Φ) was 2.33 and 2.36 for males and females, respectively. Results were similar to other geographical areas, which suggests that a common fisheries management might be possible.  相似文献   

2.
The fecundity of the bogue from the Portuguese coast was assessed by the volumetric method using 75 ovaries in prespawning stage from fishes between 14 and 36 cm total length (TL). Estimates of total potential annual fecundity varied between 11550 and 357800 eggs per female. Relationships between fecundity and total length, total weight (TW) and age (A) were established, the former being a better-suited prediction of fecundity according to the equation: F = 15632 (TL) - 228717. Relative fecundity was determined. Maximum values corresponded to females between 21 and 26 cm total length.  相似文献   

3.
In recent years, jellyfish blooms have attracted considerable scientific interest for their potential impacts on human activities and ecosystem functioning, with much attention paid to jellyfish as predators and to gelatinous biomass as a carbon sink. Other than qualitative data and observations, few studies have quantified direct predation of fish on jellyfish to clarify whether they may represent a seasonally abundant food source. Here we estimate predation frequency by the commercially valuable Mediterranean bogue, Boops boops on the mauve stinger jellyfish, Pelagia noctiluca, in the Strait of Messina (NE Sicily). A total of 1054 jellyfish were sampled throughout one year to quantify predation by B. boops from bite marks on partially eaten jellyfish and energy density of the jellyfish. Predation by B. boops in summer was almost twice that in winter, and they selectively fed according to medusa gender and body part. Calorimetric analysis and biochemical composition showed that female jellyfish gonads had significantly higher energy content than male gonads due to more lipids and that gonads had six-fold higher energy content than the somatic tissues due to higher lipid and protein concentrations. Energetically, jellyfish gonads represent a highly rewarding food source, largely available to B. boops throughout spring and summer. During the remainder of the year, when gonads were not very evident, fish predation switched towards less-selective foraging on the somatic gelatinous biomass. P. noctiluca, the most abundant jellyfish species in the Mediterranean Sea and a key planktonic predator, may represent not only a nuisance for human leisure activities and a source of mortality for fish eggs and larvae, but also an important resource for fish species of commercial value, such as B. boops.  相似文献   

4.
In experiments with dialized neurons of L. stagnalis mollusc the recovery of Na-current (INa) after its depression by local anesthetic trimecaine and its quaternary derivative N-ethyltrimecaine (G-88) was studied. A full recovery of INa within tens of seconds after washing off trimecaine but not G-88 was observed. The half-time for vanishing of INa use-dependent depression by G-88 was 17 minutes, and there was no substantial vanishing of tonic INa block even after an hour of G-88 washing off. A hypothesis is advanced that the long recovery time of INa is one of the mechanisms providing long pharmacological action of quaternary antiarrhythmic and local anesthetic ammonium compounds.  相似文献   

5.
《Biophysical journal》2020,118(3):624-642
Lipid bilayers can exhibit asymmetric states, in which the physical characteristics of one leaflet differ from those of the other. This most visibly manifests in a different lipid composition, but it can also involve opposing lateral stresses in each leaflet that combine to an overall vanishing membrane tension. Here, we use theoretical modeling and coarse-grained simulation to explore the interplay between a compositional asymmetry and a nonvanishing differential stress. Minimizing the total elastic energy leads to a preferred spontaneous curvature that balances torques due to both bending moments and differential stress, with sometimes unexpected consequences. For instance, asymmetric flat bilayers, whose specific areas in each leaflet are matched to those of corresponding tensionless symmetric flat membranes, still exhibit a residual differential stress because the conditions of vanishing area strain and vanishing bending moment differ. We also measure the curvature rigidity of asymmetric bilayers and find that a sufficiently strong differential stress, but not compositional asymmetry alone, can increase the bending modulus. The likely cause is a stiffening of the compressed leaflet, which appears to be related to its gel transition but not identical with it. We finally show that the impact of cholesterol on differential stress depends on the relative strength of elastic and thermodynamic driving forces: if cholesterol solvates equally well in both leaflets, it will redistribute to cancel both leaflet tensions almost completely, but if its partitioning free energy prefers one leaflet over the other, the resulting distribution bias may even create differential stress. Because cells keep most of their lipid bilayers in an asymmetric nonequilibrium steady state, our findings suggest that biomembranes are elastically more complex than previously thought: besides a spontaneous curvature, they might also exhibit significant differential stress, which could strongly affect their curvature energetics.  相似文献   

6.
Growth of Boops hoops Linnaeus, 1758 (Pisces, Sparidae) in the golf of Lion The authors give the equations age-length, age-mass and mass-length of Boops boops living in the golf of Lion. Age has been determined by scalimetry. This study has shown that there is no difference between males and females and that the growth (lenght and mass) of the bogue along the French mediterranean coast is less on the Spanish and libanish coast.  相似文献   

7.
ABSTRACT. Conjugating cells of Euplotes vannus (syngens Naples and Barcarès) were investigated for Con A-binding sites by means of fluorescence microscopy. Cells fixed with 0.4% paraformaldehyde and incubated with 15 μg/ml FITC-Con A showed a distinct region of strong fluorescence, the size, shape and localization of which characteristically changed during the course of conjugation, first appearing at courtship stage (cells contact without forming pairs) and vanishing soon after the migration pronuclei have been exchanged, but before cells have separated. Con A binding and conjugation were blocked by cyclohexamide and α-galactosidase. Con A-binding was also inhibited by α-mannosidase, α-glucosidase and β-galactosidase without affecting conjugation except a delay of pair formation. The results suggest an involvement of newly formed or translocated glycoconjugates in cell pairing during conjugation.  相似文献   

8.
Six species of digeneans, including three new host records, are described from the bogue Boops boops off the Spanish NE Atlantic and the Mediterranean coasts. The species involved are: Robphildollfusium martinezgomezi López-Román, Gijón-Botella, Kim & Vilca-Choque, 1992, Magnibursatus caudofilamentosa (Reimer, 1971) Gibson & K?ie, 1991, Lepocreadium album Stossich, 1890, Steringotrema pagelli (van Beneden, 1871) Odhner, 1911, Tetrochetus coryphaenae Yamaguti, 1934 and Stephanostomum euzeti Bartoli & Bray, 2004 (metacercaria). B. boops is a new host for 11 metazoan parasites (six digeneans, three acanthocephalans, one copepod and one isopod) recovered in this study. These are reported and incorporated into a complete checklist of the metazoan parasites of B. boops throughout its distributional range. It comprises summarised information for 67 species in 260 host-parasite records and includes the name of the parasite species, the locality of the host, and the author and date of the published record. The taxonomy is updated and annotations are made on the validity of the records and synonymies.  相似文献   

9.
Summary This paper compares the vanishing bearings of White-throated Sparrows released from orientation cages and tracked visually, with the preferred orientation directions indicated by hopping in the cage immediately prior to release. These directions where then compared with the directions of recoveries of birds ringed during migration. The vanishing bearings were well-oriented and northward (6°). The orientation directions of the same birds in the cages were variable with a mean toward northwest (334°). Although on average the vanishing bearings differed from the direction indicated in the cage by only 29°, there was rarely close correspondence between them. Spring ringing recoveries were tightly clumped around a mean of 45°, and their distribution differed from that of both the vanishing bearings and cage orientation directions. These results provide little support for the assumption that what we observe in an orientation cage precisely reflects what a bird would do if actually migrating.
Zusammenfassung Diese Arbeit vergleicht die Verschwinderichtung von Weißkehlammern (Zonotrichia albicollis), freigelassen aus Orientierungskäfigen und visuell verfolgt, mit der von ihnen bevorzugten Orientierungsrichtung in den Käfigen, die sie durch Hüpfen unmittelbar vor dem Freilassen zeigen. Die Verschwinderichtung der Versuchsvögel nach dem Freilassen war eindeutig nordwärts (6°) gerichtet. Die Orientierungsrichtung derselben Vögel in den Käfigen variiert um den Mittelwert 334° Nordwest. Obwohl die durchschnittliche Abweichung der Verschwinderichtung von der Orientierungsrichtung in den Käfigen nur 29° beträgt, ist das als eine geringe Übereinstimmung zu werten. Beide Richtungen wurden mit der Zugrichtung von freilebenden beringten Vögeln verglichen. Wiederfänge dieser Vögel im Frühjahr zeigen eine Orientierung mit Mittelwert 45° bei geringer Streuung. Diese Richtung weicht von denen im Versuch beobachteten Käfigorientierung und der Verschwinderichtung ab. Die Ergebnisse stützen nicht die Annahme, daß die beobachtete Orientierungsrichtung in Käfigen präzise die Zugrichtung eines Vogels in Freiheit wiederspiegelt.
  相似文献   

10.
An ultrastructural study on dividing PKEV cells provided a possibility to distinguish between certain stages of their desintegration. The changes preceding fragmentation of the nuclear envelope commence with desorganization of its structural components: vanishing of granular peripherial chromatin layer; appearance of the pores without central granules; formation of deep invaginations of the nuclear membranes. The desintegration of the nuclear envelope starts from the disapearance of many pores and the appearance of perforations almost of the same size. Simultaneously, the number of polysomes is reduced on the outer membrane of the nuclear envelope and in the cytoplasm. Specific features of the nuclear envelope being lost it becomes undistinguishable from the reticulum elements. On serial sections, no contacts were observed between chromosomes and membranous elements.  相似文献   

11.
A remarkable phenomenon of dense Boops boops shoals appearing almost adjacent to the shoreline during nighttime is known to the locals of island communities of the Aegean Sea (eastern Mediterranean). In this work, we investigated this appearance testing the hypotheses that (a) it may occur only in anthropogenically modified locations (as suggested by previous observations), (b) the migration pattern to the littoral is not arbitrary but synchronized to the sunset/sunrise, (c) fish abundance is affected by location, season and/or natural (moon) light fluctuations. Quantitative sampling included visual observations from the coast at five stations in Syros (Cyclades, Greece) from July 2009 to September 2010. Both hypotheses concerning occurrence only in anthropogenically modified locations and timing with sunset/sunrise were confirmed. Fish abundance was modelled using generalized additive models, demonstrating a seasonal pattern and revealing significant differences among sampling stations, but no moon-phase effects. The phenomenon investigated here has implications for fisheries management, as the shoal proximity to the shore renders them prone to illegal harvesting (seasonally at high abundances), aggravating the problem of illegal, unreported and unregulated fishing. Further considerations on the integrated management of the coastal zone arise, especially concerning the effects of habitat structural modification and light pollution.  相似文献   

12.
The host‐parasite relationship between bogue (Boops boops) and Cerathotoa parallela (Isopoda: Cymothoidae) was studied in the Southern Tyrrhenian Sea (overall prevalence of isopods in the area, age‐dependent and sex‐dependent prevalence). Yearly prevalence ranged from 1.0% in March to 10.7% in October, with a positive correlation between prevalence and mean sea surface temperatures (SST), highest values being related to the period of increasing SST. The first four age‐classes were parasitized, with prevalence decreasing according to the age of the host. The relationship between total length (TL) and total weight (TW) was examined in infested and non‐infested specimens of the same age whereby slight differences were detected, i.e. at a given length non‐infested specimens weighed more than infested fishes. The parasite occurred throughout the study area with wide fluctuations in prevalence, from 0 to 36.4%, the values being higher in the eastern part of the study area. C. parallela parasitize the bogue Boops boops in a manner that does not constitute a serious threat to the life of the host.  相似文献   

13.
Three new species of Acizzia are described from Australian mistletoe (Loranthaceae: Amyema spp.). These are: A. loranthacae sp. n., A. amyemae sp. n. and A. pendulae sp. n. They are characterised by: male proctiger with prominent posterior lobe; antenna 1.9–2.9 times width of head; forewing with costal break and pterostigma, with pattern in A. amyemae and A. pendulae but not in A. loranthacae ; and female proctiger simple in A. amyemae and A. pendulae but with prominent dorso-apical process in A. loranthacae . The Loranthaceae is a new host family record for Acizzia . Given the probable radiation of Acizzia on mimosaceous hosts, its occurrence on eucalypt-inhabiting mistletoe, yet its apparent absence from mistletoes on Acacia, is discussed.  相似文献   

14.
Eukaryotic initiation factor 2B (eIF2B) plays a key role in protein synthesis and in its control. It comprises five different subunits, α-ε, of which eIF2Bε contains the catalytic domain. Formation of the complete complex is crucial for full activity and proper control of eIF2B. Mutations in the genes for eIF2B cause an often severe neurological disorder, "vanishing white matter." eIF2Bγ and eIF2Bε contain homologous and conserved domains with sequence similarity to nucleotidyl transferases (NTs) and acyl transferases and can form a binary complex. The latter contain a hexad repeat that mainly comprises isoleucyl residues (hence termed the "I-patch" region). These data reveal that certain residues in the NT domains of eIF2Bγ/ε, which are highly conserved throughout eukaryotes, play key roles in the interactions between subunits in the eIF2B complex. Our data show that the I-patch regions are important in the interactions between the catalytic eIF2Bγε complex and the other subunits. We also studied the functional effects of vanishing white matter mutations in the NT and I-patch domains. Lastly, our data show that eIF2Bγ promotes the expression of eIF2Bε, providing a mechanism for achieving correct stoichiometry of these eIF2B subunits in the cell.  相似文献   

15.
Abstract. 1. Various aspects were studied of two host-parasitoid interactions: Aphidius urticae parasitizing the cocksfoot aphid Hyalopteroides humilis and Aphidius uzbeckistanicus parasitizing the cereal aphid Metopolophmm dirhodum. The work formed part of a study on the population dynamics of grassland and cereal aphids in Berkshire, England.
2. A.uzbeckistanicus had a higher instantaneous attack rate but a slightly longer handling time than A.urticae. In both cases the functional response was curvilinear.
3. A.urticae was specific to H.humilis and failed to develop in M.dirhodum. A.uzbeckistanicus could develop successfully in H.humilis but the functional response was sigmoid and the progeny were less fecund than those reared on the natural host. This species showed a clear preference for M.dirhodum when supplied with mixtures of M.dirhodum and H.humilis.
4. A.uzbeckistanicus had a faster rate of development and a lower developmental threshold than A.urticae , a situation paralleled by their natural hosts.
5. The results are discussed in relation to field observations. A.uzbeckistanicus may have considerable potential for reducing cereal aphid numbers. However, its preference for M.dirhodum mitigates against a reservoir being maintained in the economically unimportant grassland aphid, H.humilis.  相似文献   

16.
Discrimination of intra- and intermolecular hydrogen bonds in a symmetric multimer has not been accomplished yet, although such discrimination would provide a crucial basis for construction of the multimeric architecture of nucleic acids by NMR. We have developed a direct and unambiguous method for such discrimination involving the use of scalar couplings across hydrogen bonds. The method has been validated with a symmetric dimer of d(GGGCTTTTGGGC), for which the structure including both intra- and intermolecular hydrogen bonds was already reported. This has demonstrated that our method can clearly discriminate these two kinds of hydrogen bonds. Then, the method was applied to a symmetric dimer of d(GGAGGAGGAGGA) and has provided decisive information on its multimeric architecture. Additionally, the values for scalar couplings across hydrogen bonds for G:G and G:A base pairs in the G(:A):G(:A):G(:A):G heptad formed by d(GGAGGAGGAGGA) were determined for the first time. This determination has provided an insight into the nature of the heptad.  相似文献   

17.
18.
目的:分析和总结小儿慢性胃炎的消化道外表现。方法:选择2008年1月~2008年10月哈尔滨医科大学附属第二医院儿科门诊诊治的经腹部胃区叩诊法确诊为慢性胃炎的患儿864例,建立随访卡片,分析和总结其消化道内及消化道外的临床表现。结果:864例患儿常见的消化道症状依次为腹痛、恶心呕吐、便秘、上腹压痛。消化道外表现依次为头痛、刀枪刺、鼻出血、胸痛、多动抽动、手足搐搦。消化道外表现的发病率并不低于消化道表现,特别是头痛的发病率高达58.54%。腹痛、恶心呕吐症状缓解得最快,其次是头痛、头晕、胸闷、胸痛,多动症状较晚缓解,腹部叩痛的消失时间最晚。结论:小儿慢性胃炎的胃肠道外表现广泛存在,且极易与脑炎、心肌炎误诊,值得关注。头痛、胸痛的产生原因可能与内脏-内脏之间的牵涉痛有关。  相似文献   

19.
BACKGROUND: Using a single-platform protocol to count absolute CD34+ hematopoietic precursor cell (HPC) levels with different reference microbeads, we recorded occasionally artifactually high CD34+ HPC counts in some leukapheresis bags, whereas dual-platform calculations were always consistent. Abnormal countings were observed only when phosphate-buffered saline (PBS)-diluted leukapheresis samples were vortexed before analysis. A large series of blood samples analyzed similarly for CD34+ and CD4+ absolute counts did not show any sample or vortexing effect. With the volumetric absolute counting cytometer Partec-PAS, lower counts were also observed when different reference beads were vortexed before the instrument checking procedures. The counting abnormality was caused by a drop in microbead concentration (the "vanishing bead phenomenon"). This phenomenon reduced the total and relative bead event number in experimental and routine samples and in calibration procedures. This altered the bead denominator used to calculate absolute CD34+ HPC levels and it also reduced the concentration of standard calibration beads. METHODS: Using the Partec-PAS to measure volumetrically the actual bead concentration, we studied the vanishing bead phenomenon. Different types of counting and reference microbeads were resuspended in media with or without proteins or cells. Replicates were submitted either to gentle manual mixing or to vortexing before counting. RESULTS: Vortex agitation almost invariably induced the vanishing bead phenomenon when beads were resuspended in saline media or when an insufficient protein concentration was present, such as in diluted leukapheresis samples. Different bead types showed various degrees of sensitivity to vortexing. The bead disappearance was not caused by bubble formation or disruption. The addition of small amounts of protein completely prevented the vanishing bead phenomenon. The causative effect of the electrostatic charging of tube induced by vortexing is hypothesized. CONCLUSIONS: Sample suspensions containing counting beads for single-platform analysis must be resuspended in media with protein supplements to prevent the vanishing bead phenomenon and to ensure accurate counting.  相似文献   

20.
Ascarops talpa sp. n. (Nematoda: Spirocercidae) is described from the small intestine of the Formosan mole, Talpa micrura insularis, from Taiwan. It is most similar to A. kutassi (Shul'ts, 1927) and A. tuvensis Sulimov, 1961. Ascarops kutassi differs by having a smaller ratio of left to right spicule length (1:4 vs. 1:5.5), no caudal alae, by its preanal papillae that are not equidistant from one another, and in its area rugosa which extends 1.25 mm anterior to the anus. Ascarops tuvensis differs by having a smaller ratio of left to right spicule length (1:3.8 vs. 1:5.5), by its preanal papillae that are not equidistant from one another, and in its area rugosa which covers only the ventral tip of the tail.  相似文献   

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