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31.
Methodological investigations, using remains of Bosminidae and Chydoridae, were undertaken to study the development of ecosystems
in former river channels. Four biotopes from two former channels of different ages were used in this work. The Copepoda and
Cladocera populations characterized each of the 11 sampling stations in relation to ecological factors, which are linked to
the development stage in each ecosystem. Analysis of only the Bosminidae and Chydoridae populations presented practically
the same information as an analysis of the total populations of Copepoda and Cladocera. The distribution of Bosminidae and
Chydoridae remains taken from the surficial sediments at the deepest point of each former channel strongly resembled the distribution
of the living populations sampled at several stations during one full year. Therefore, Bosminidae and Chydoridae remains could
provide us with pertinent information concerning each phase of ecological succession that occurs in abandoned river channels. 相似文献
32.
Steven Branstetter 《Environmental Biology of Fishes》1987,19(3):161-173
Synopsis The silky shark, Carcharhinus falciformis, and scalloped hammerhead, Sphyrna lewini, represent >80% of the shark by-catch of the winter swordfish/tuna longline fishery of the northwestern Gulf of Mexico. This
catch represents a potential supplemental fishery, yet little is known of the life histories of the two species. This report
relates reproductive biology data to age and growth estimates for 135 C. falciformis and 78 S. lewini. Unlike other regional populations, C. falciformis in the Gulf of Mexico may have a seasonal 12 month gestation period. Males mature at 210–220 cm TL (6–7 yr); females at >225
cm TL (7–9 yr). Application of age at length data for combined sexes produced von Bertalanffy growth model parameter estimates
of L∞ = 291 cm TL, K = 0.153, t0 = −2.2 yr. Adult male S. lewini outnumbered adult females in catches because of differences in the distributions of the sexually segregated population. Males
mature at 180 cm TL (10 yr); females at 250 cm TL (15 yr). von Bertalanffy parameter estimates for combined sexes of this
species were L∞ = 329 cm TL, K = 0.073, to = −2.2 yr. 相似文献
33.
Methods of hatching the eggs and rearing the fundatrices of the English grain aphid, Sitobion avenae
Several methods for hatching the eggs and rearing individuals of the first generation (fundatrices) of Sitobion avenae were investigated. The most successful methods were incubation of the eggs on grass seedlings at 2°C and rearing the fundatrices on grass seedlings (overall survival 66%) and incubation of the eggs in plastic boxes at 2°C and rearing the fundatrices on wheat seedlings (overall survival 62%).
Résumé L'éclosion des oeufs de S. avenae peut être induite par le transfert à 10°C ou 12°C, après une incubation de 75–120 jours à 2°C. Le pourcentage le plus élevé d'éclosions a été obtenu quand les oeufs avaient incubé pendant 100 à 110 jours à 2°C (67% at 71.5% respectivement) dans des petites boîtes de plastique, ou pendant 100 jours à 2°C sur des pousses de graminées (73.5%). Si les oeufs sont pondus sur blé, la plante ne peut pas tolérer la période d'incubation, mais cet obstacle peut être surmonté en obligeant les ovipares à pondre leurs oeufs sur de pousses de graminées, comme Poa annua, hôte convenable pour les fondatrices. Les ovipares peuvent aussi pondre sans difficultés sur autre chose que des végétaux, et des récipients peuvent ètre mis à incuber sans contenir du matériel végétal.相似文献
34.
Torsten Mattfeldt 《Journal of mathematical biology》1987,25(6):685-695
The absolute volume of biological objects is often estimated stereologically from an exhaustive set of systematic sections. The usual volume estimator
is the sum of the section contents times the distance between sections. For systematic sectioning with a random start, it has been recently shown that
is unbiased when m, the ratio between projected object length and section distance, is an integer number (Cruz-Orive 1985). As this quantity is no integer in the real world, we have explored the properties of
in the general and realistic situation m . The unbiasedness of
under appropriate sampling conditions is demonstrated for the arbitrary compact set in 3 dimensions by a rigorous proof. Exploration of further properties of
for the general triaxial ellipsoid leads to a new class of non-elementary real functions with common formal structure which we denote as np-functions. The relative mean square error (CE
2) of
in ellipsoids is an oscillating differentiable np-function, which reduces to the known result CE
2= 1/(5m
4) for integer m. As a biological example the absolute volumes of 10 left cardiac ventricles and their internal cavities were estimated from systematic sections. Monte Carlo simulation of replicated systematic sectioning is shown to be improved by using m instead of m . In agreement with the geometric model of ellipsoids with some added shape irregularities, mean empirical CE was proportional to m
–1.36 and m–1.73 in the cardiac ventricle and its cavity. The considerable variance reduction by systematic sectioning is shown to be a geometric realization of the principle of antithetic variates. 相似文献
35.
Douglas M. Templeton Anna Paudyn Andrew D. Baines 《Biological trace element research》1989,22(1):17-33
Interest in the biological behavior of a growing number of elements, along with increasing recognition of the importance of interactions among them, demands a versatile and reliable technique for multielement analysis of biological samples. Significant improvements over the sensitivity achieved with conventional inductively coupled plasma (ICP) optical emission spectrometries have been realized with the introduction of quadrupole mass spectrometry (MS) for detection of ions in the plasma. The hybrid technique of ICP-MS promises to be a method of rapid multielement analysis, at detection limits that approach or surpass those of other technologies. However, the application of ICP-MS to analyses of biological interest is truly in its infancy. Here we report the use of ICP-MS for the determination of more than 30 elements of biological interest in a tissue and a biological fluid (rat liver and serum, respectively). Experimental values of the elements serve as a basis for discussion of analytical protocols, performance criteria, and certain problems peculiar to ICP-MS. 相似文献
36.
M. D. Poli 《Human Evolution》1988,3(6):487-502
The ability to learn is common to most animal species: the need to exploit past experience being obviously extremely important for survival, many animals have evolved ways of coping with it. Although the complexity of learning needed for optimal survival may be different in different species, the basic mechanisms appear to be fairly constant even in phylogenetically distant ones. This homogeneity across species in learning mechanisms is in some ways surprising in view of the large phylogenetic differences and of the considerable variability not only in the general plan of their bodily structures, but also, more specifically, in their neural organization and in their behavioral adaptations. One possible explanation is that animals have acquired learning very precociously, and that the original and basic mechanisms have proved so efficient and faultproof as to be preserved from then on without any significant modification. Most researchers of the subject seem to accept the equation «intelligence=learning capability», operationally very useful because it leads to a variety of formal tests. Some researchers, stressing that behavior is subject to the same evolutionary principles as any other character of the organism and acknowledging some problems in the accepted laws of learning, have tried to find a satisfactory answer to the question of animal intelligence by attempting a synthesis between the concepts of animal learning psychology and those of ethology. To some extent, dissatisfaction with established learning theories originated within the theories themselves: the study of phenomena such as autoshaping, selective attention, preferential learning of some responses amongst the many possible, conditioned learning of taste aversions, etc. Further difficulties for conditioning theories arose from the discovery of ethological phenomena. Other researchers have attempted to check the hypothesis that animals possess cognition. A number of complex experimental situtations have been devised to this purpose, but the results still are far from conclusive. 相似文献
37.
Allometric methods can be used to test quantitative theories of the relationship between brain size and body size across species,
and to search for ecological, behavioural, life history, and ontogenetic correlates of brain size. Brain size scales with
an allometric exponent of around 0.75 against body size across mammals, but is closer to 0.56 for birds and for reptiles.
The slope of the allometric line often varies depending upon the taxonomic level of analysis. However, this phenomenon, at
least in mammals, may be a statistical artifact. Brain size for a given body size (relative brain size) varies among orders
in birds and mammals, and some dietary associations with relative brain size have been found in particular taxa. Developmental
status at birth is the most consistent correlate of relative brain size: precocial neonates have larger brains for a given
maternal size than altricial neonates in both birds and mammals. Altricial neonates, however, have more brain growth following
birth, and in birds also have larger relative adult brain sizes. Energetic explanations for differences in neonatal brain
growth, although attractive on theoretical grounds, have largely failed to stand up to empirical tests. 相似文献
38.
Filtration rate capacities in 6 species of European freshwater bivalves 总被引:12,自引:0,他引:12
Summary Filtration rate capacities in undisturbed freshwater bivalves were determined by means of two different methods (indirect clearance and suction methods) in Anodonta anatina (L.), Unio tumidus Philipsson, Unio pictorum (L.), Unio crassus Philipsson, Dreissena polymorpha (Pallas) and Sphaerium corneum (L.). In A. anatina, D. polymorpha, and S. corneum the filtration rate (FR, 1 h-1) at 19–20°C as a function of dry tissue weight (DW, g) or ash-free dry weight (AFDW, g) could be expressed by the equations: 1.10 DW0.78, 6.82 DW0.88, and 2.14 AFDW0.92, respectively. In U. tumidus, U. pictorum, and U. crassus filtration rates were comparable with those of A. anatina. In D. polymorpha the b value of the corresponding regression of gill area on dry weight was 0.87. The rates of water transport in freshwater bivalves are 2–8 times lower than in marine bivalves of comparable size. A corresponding difference in the filtration rate per gill area unit is found. The measured filtration rates in undisturbed bivalves are substantially higher (at least 4 times) than previously reported. This indicates that the impact of bivalve water processing on freshwater ecosystems is greater than hitherto suggested. 相似文献
39.
Responses of seed germination to salinity were examined using 37 species collected from salt marshes, cliffs, and fore (unstable)
and hind (stable) sand dunes along Japanese coasts. For comparison, seed germination of nine inland species was also examined.
The soil salinities in salt marshes ranged from 150 to 300 mmol/L NaCl, whereas those in fore and hind dunes ranged from 0
to 150 mmol/L NaCl, with a few exceptions. Cliff soils showed relatively high salinities up to 300 mmol/L NaCl. Ciff and foredune
soils that encountered a typhoon and storm showed high salinities >300 mmol/L NaCl. Salt tolerance in seed germination of
coastal plants was ordered by comparing the responses of percentage and rate of germination to salinity conditions up to 200
mmol/L NaCl, being in the order of salt marsh>cliff>foredune≅hind dune≅inland. Thse results indicate that salt tolerance in
seed germination of coastal plants is closely related to the salinity conditions of their habitats. Germination experiments
under favorable conditions showed that a high percentage of the seeds of salt marsh species germinate rapidly, those of diff
species germinate slowly and those of foredune species exhibit a low percentage and low rate of germination. It seems that
these germination characteristics contribute to the success of germination at the ‘safe site’ and the subsequent survivorship
of emerged plants in their natural habitats. 相似文献
40.
Regarding biological products, increasing awareness of potential side effects have placed great importance not only at protein
purity regarding other proteins but on the removal of biologicals such as DNA and especially virus the importance of which
may not be known. Monoclonal antibodies (Mab) have come to be an important class of molecules obtained from hybridoma cells,
i.e., nonrecombinant cells in culture. It has been noted during the last years, that with rare exceptions hybridoma cell lines
contain retrovirus like particles. The infectious nature of the EM-visible particles has been tested for, however, in most
cases not been substantiated. In order to bring these valuable biological reagents, Mab's, to good use in man for imaging
or therapy, the remaining concern about a potential retroviral infection has to be reduced to an acceptable minimum. We describe
experimental approaches for the validation of chromatographic and ultrafiltration steps used in the production of monoclonal
antibodies to remove and inactivate murine retrovirus.
Present day biotechnological manufacturing processes have been devised incorporating a number of strategic preventive measures
that have found wide spread acceptance. They permit to answer the question: how can a potentially harmful infection by an
unknown virus be excluded.
Knowledge of the efficacy of purification steps to clear infectious model virus is fundamental to devise biotechnological
manufacturing processes yielding a purified antibody for use in man. 相似文献