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1.
The first stage phyllosoma of Parribacus caledonicus, Scyllaridessquammosus and Arctides regalis hatched in aquaria from berriedfemales are described and illustrated. The three phyllosomataare very similar but they can be distinguished by three characters:total length, ratio of total length to third pereiopod lengthand the setation and spination on the second maxilla. A summaryis provided of those morphological characters of the first phyllosomataattributed to these genera in the literature.  相似文献   

2.
The Lig. phrenicopericardiacum of wolves who lived in captivity has been examined with regard to the following aspects: origin, run, insertion, size (breadth and length), and form. The findings of investigations were compared with the corresponding ones stated in the literature for dogs; the correspondences as well as the differences between the both species were pointed out and the possible reasons for them were discussed.  相似文献   

3.
The northern portion of the geographic range of the American eel Anguilla rostrata may contribute a great proportion of the reproductive potential to this panmictic species because of apparent increases in average female size and female percentage with latitude. The regressions of fecundity on body length and on body weight of 63 female eels captured at about 45° N latitude on their spawning migration to the sea were log F= 1·2601 + 2·9642 log L and log F= 4·1646+0·9153 log W , where F is fecundity, L is total length (cm), and W is total weight (g). Length and weight each explained about 90% of the variation in fecundity. Estimates of fecundity from counts of aliquots of eggs ranged from 1·84 million to 19·92 million eggs for eels ranging in length from 45 to 113 cm, nearly the range of sizes of migrating females reported in the literature. Fecundities of the American eel were greater than reported in one study at about 37° N and greater than reported for the European eel, A. anguilla , shortfin eel, A. australis , and longfin eel, A. dieffenbachii . If a geographic cline in fecundity does exist in American eels, it is established anew each generation because the species forms a single panmictic population.  相似文献   

4.
The development of lateral plate number in completely plated three-spined stickleback populations during the period of growth of the body after hatching was studied in two streams in Central Poland. The streams belong to the Oder River drainage basin (51°38'N; 19°26'E) and the Vistula River drainage basin (51°35'N; 19°37'E), respectively. After reaching a total length of 27 mm the development of lateral plate number is completed in both populations. This value is lower than thc corresponding values rcported in the literature.  相似文献   

5.
This paper describes the gravel type and structure of brown trout spawning gravels in Teesdale, the flow characteristics of the spawning sites and the size of redds. Factors influencing redd size are investigated and it is concluded that female size is a major factor. Relationships are established between various redd characteristics and the fork length of female fish. The findings are discussed in relation to the existing literature concerning salmonid spawning sites.  相似文献   

6.
The maximum cylindrical diameter of fussion yeast cells was measured using an image-shearing eyepiece with an optical microscope. The mean diameters were 3.4, 3.8, 4.2, 4.4 and 4.8 μm for cells bearing one to five fission scars, respectively. These increments amount to about 10% per generation, and correspond to 10% increases in cellular surface area during expansion. This result was found wholly comparable with areal increases of Saccharomyces adult cells calculated from length and width data in the literature). Extant notions about growth of yeast cell walls are inadequate to explain these size increases.  相似文献   

7.
A Markov process with absorbing boundaries may be made recurrent by returning the process to the interior whenever a boundary is reached. The age of such a process may be defined as the length of time since the last return event. Examples drawn from two-allele genetic models are discussed, in which reversibility of the return process means that the age of an allele, whose present frequency in the population is known, has the same probability distribution as its future extinction time. Some discrete models are not reversible, yet if approximated by diffusion processes, the (approximate) age distribution is the same as the future extinction time distribution. Various results in the literature are unified by this viewpoint.  相似文献   

8.
Crosses between African and European honeybees in Brazil resulted in a highly defensive hybrid bee. The acid gland is important in the expression of this characteristic, being responsible for venom production. Morphological variations in this gland could influence the quantity of venom. Glandular morphology was analyzed, along with the quantity of venom produced and the bees' genetic characteristics. The gland and the venom reservoir were removed from workers. The gland was placed on a histological frame for measurement and the contents of the reservoir were weighed. The results were submitted to an analysis of regression and submitted to Test Z, to evaluate the differences between the averages. The phenotypes were evaluated according to the standard found in literature. Gland length varied from 7.42 mm to 20.33 mm, the quantity of venom from 0.19 mg to 0.34 mg, and as far as the genetic characteristics are concerned, 63.3% of the colonies had workers with large glands. In 53.3% of the colonies, 90% of individuals had simple glands, suggesting the evolutionary process leading to the loss of branching, since the presence of branching indicates primitiveness. The production of venom is associated with the length of the gland and branching does not influence the quantity of venom. There was no statistical difference between the size of the branched and simple glands or in the quantity of venom produced, therefore the large glands can favor commercial exploration of venom, producing larger quantities.  相似文献   

9.
The age and growth of the Cyprinid fish Barilius moorii from Lake Kivu is studied by means of the growth rings occurring in the scales. Although the moment of ring formation and the duration of one growth season were not known, both overall length growth in a population as well as individual length growth could be calculated. Increase of weight was obtained from length growth on the basis of a length-weight relationship. By comparing the growth parameters of the von Bertallanfy equation and data from the literature, a hypothesis is formulated that ring formation should occur at the transition from a dry to a rainy season, and that two rings a year should be formed. Ring formation on the scales might be due to gonad maturation, but this could not be demonstrated.  相似文献   

10.
How viable is the argument that increased locomotor efficiency was an important agent in the origin of hominid bipedalism? This study reviews data from the literature on the cost of human bipedal walking and running and compares it to data on quadrupedal mammals including several non-human primate species. Literature data comparing the cost of bipedal and quadrupedal locomotion in trained capuchin monkeys and chimpanzees are also considered. It is concluded that increased energetic efficiency would not have accrued to early bipeds. Presumably, however, selection for improved efficiency in the bipedal stance would have occurred once the transition was made. Would such a process have included selection for increased limb length? Data on the cost of locomotion vs. limb length reveal no significant relationship between these variables in 21 species of mammals or in human walking or running. © 1996 Wiley-Liss, Inc.  相似文献   

11.
Polymorphism of chromosome 9 in 600 Greek subjects.   总被引:1,自引:0,他引:1  
The morphologic variations of C-band heterochromatin of chromosome 9 were studied in 600 Greek subjects referred for cytogenetic investigation. There was great variability in the location and length of the heterochromatic bands. The location and length of the heterochromatic band were equal in 177 individuals and unequal in 423. Twenty-five subjects (4%) carried a pericentric inversion on one of the homologs, and 12 individuals (2%) had an extremely elongated C-band in one homolog 9. Our findings are compared with those reported in the literature, and the ethnic variation is discussed and evaluated.  相似文献   

12.
The equilibrium Kerr effect of a system of mobile charges constrained to the surface of biomacromolecules is calculated. Cylindrical and spherical geometries are considered. For the cylinder we determine the anisotropy of electric polarizability as a function of length, temperature, and number of charged species in the low-field regime, and the fraction of the maximum induced dipole in the field direction for higher electric fields. The results are compared to experimental data for DNA oligomers taken from the literature. With spherical geometry we calculate the fractional induced dipole moment as a function of electric field strength and from this deduce the orientation function. The field dependence of the orientation function is compared to experimental data in the literature for bovine disk membrane vesicles.  相似文献   

13.
Lepidagathis benojiana, a new species of Lepidagathis, collected from the Idukki district, Kerala, southern Western Ghats, India is described along with photographs. The new species is closely allied to L. chlorostachya Nees. but differs from the latter in its height, length of petiole, position and number of spikes, length of peduncle, length of floral whorls, colour of flower, colour and nature of stamens, nature of fruit and shape of the seed.  相似文献   

14.
Located on the sensory epithelium of the sickle-shaped cochlea of a 7- to 10-d-old chick are approximately 5,000 hair cells. When the apical surface of these cell is examined by scanning microscopy, we find that the length, number, width, and distribution of the stereocilia on each hair cell are predetermined. Thus, a hair cell located at the distal end of the cochlea has 50 stereocilia, the longest of which are 5.5 microns in length and 0.12 microns in width, while those at the proximal end number 300 and are maximally 1.5 microns in length and 0.2 micron in width. In fact, if we travel along the cochlea from its distal to proximal end, we see that the stereocilia on successive hair cells gradually increase in number and width, yet decrease in length. Also, if we look transversely across the cochlea where adjacent hair cells have the same length and number of stereocilia (they are the same distance from the distal end of the cochlea), we find that the stereocilia of successive hair cells become thinner and that the apical surface area of the hair cell proper, not including the stereocilia, decreases from a maximum of 80 microns2 to 15 microns2. Thus, if we are told the length of the longest stereocilium on a hair cell and the width of that stereocilium, we can pinpoint the position of that hair cell on the cochlea in two axes. Likewise, if we are told the number of stereocilia and the apical surface of a hair cell, we can pinpoint the location of that cell in two axes. The distribution of the stereocilia on the apical surface of the cell is also precisely determined. More specifically, the stereocilia are hexagonally packed and this hexagonal lattice is precisely positioned relative to the kinocilium. Because of the precision with which individual hair cells regulate the length, width, number, and distribution of their cell extensions, we have a magnificent object with which to ask questions about how actin filaments that are present within the cell are regulated. Equally interesting is that the gradient in stereociliary length, number, width, and distribution may play an important role in frequency discrimination in the cochlea. This conclusion is amplified by the information presented in the accompanying paper (Tilney, L.G., E.H. Egelman, D.J. DeRosier, and J.C. Saunders, 1983, J. Cell Biol., 96:822- 834) on the packing of actin filaments in this stereocilia.  相似文献   

15.
A case of massive ascariasis in a three and a half years old girl who eliminated 104 worms after treatment with mebendazole is reported from a riverside sector of Ri?ihue Lake, Chile. Chilean literature about intestinal massive ascariasis is reviewed. Worms showed 12-29 cm of length and 0.2-5.5 g of weight. Total worms weighted 155.8 g.  相似文献   

16.
The author discusses first of all the theoretical principles of the evolutionary myology and gives a detailed explanation on the 3 types of studies included in this complex method. The investigated material is distributed into 3 groups, which correspond to the above mentioned 3 types of studies: 1. The variations of the muscles, object of research, are studied on 200 upper limbs of adults and cn 100 limbs of human fetuses. The crown to heel length of the latter and the number of the studied limbs could be seen on the Table on page 823. 2. The comparative-anatomic research is performed on 122 limbs of animals. The different species of animals as well as the number of the examined limbs are given on the table on page 824. 3. The organogenetic material includes 18 upper limbs of human embryos and fetuses, the age of which could be seen on the table on page 825. After expressing his gratitute to all, who have assisted him in his work the author gives the already known literature data related to the phylogenesis and ontogenesis of the muscles studied by him. His own investigations start with searching of m. extensor digitorum in man, as special attention is paid both to the muscles' bellies and their tendons and the connexus intertendinei.  相似文献   

17.
Linkage map of Escherichia coli K-12, edition 8.   总被引:331,自引:10,他引:321       下载免费PDF全文
The linkage map of Escherichia coli K-12 depicts the arrangement of genes on the circular chromosome of this organism. The basic units of the map are minutes, determined by the time-of-entry of markers from Hfr into F- strains in interrupted-conjugation experiments. The time-of-entry distances have been refined over the years by determination of the frequency of cotransduction of loci in transduction experiments utilizing bacteriophage P1, which transduces segments of DNA approximately 2 min in length. In recent years, the relative positions of many genes have been determined even more precisely by physical techniques, including the mapping of restriction fragments and the sequencing of many small regions of the chromosome. On the whole, the agreement between results obtained by genetic and physical methods has been remarkably good considering the different levels of accuracy to be expected of the methods used. There are now few regions of the map whose length is still in some doubt. In some regions, genetic experiments utilizing different mutant strains give different map distances. In other regions, the genetic markers available have not been close enough to give accurate cotransduction data. The chromosome is now known to contain several inserted elements apparently derived from lambdoid phages and other sources. The nature of the region in which the termination of replication of the chromosome occurs is now known to be much more complex than the picture given in the previous map. The present map is based upon the published literature through June of 1988. There are now 1,403 loci placed on the linkage group, which may represent between one-third and one-half of the genes in this organism.  相似文献   

18.
ABSTRACT. A new species of myxosporean from the gill filaments of the freshwater teleost fish, Acestrorhynchus falcatus collected in the Amazon river is described from light and transmission electron microscope observations. The mature spores (total length 32.3 [30.7–35.1] μ) and all developmental stages were found in the same sporogonic plasmodium. The ellipsoidal spore body consists of 2 unequal shell valves adhering together along the suture lines. Each valve, tapering as a caudal projection, forms a long tail (length 20.5 [18.0–21.7] μm). The tail was surrounded by a homogeneous sheath on its length. The polar capsules measuring 3.1 × 1.2 μm contain 3–4 coils of the polar filament. All surfaces of the immature and mature spores were surrounded by a closely adherent homogenous structural sheath, mainly thicker around the tails. The taxonomic affinities of this parasite to other species are discussed.  相似文献   

19.
20.
A study was made of growth, septation and branching in Geotrichum candidum, a mould which forms physiologically complete septa. A correlation was observed between septation and branch initiation; branches were almost invariably formed just behind septa. Primary branches and their parent intercalary compartments initially increased in length at an exponential rate before eventually attaining a constant rate of extension. The whole branching system (which eventually contained seven tips) produced by an intercalary compartment increased in length exponentially until it attained a total length of at least 1-5 mm. The total length and the number of nuclei of undifferentiated mycelia increased exponentially at the same specific growth rate. The results suggest that nuclei divide just before or just after arthrospore formation.  相似文献   

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