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1.
The revision of the antarctic–subantarctic species Orchomenopsis reducta Schellenberg, 1931, has led to its attribution to a new, highly apomorphic genus: Falklandia gen.n. A new definition of the uristid group is given and Falklandia with 36 other lysianassoid genera are attributed to this supposedly monophyletic group. 相似文献
2.
Antigenic Heterogeneity of Human IgD Immunoglobulins 总被引:3,自引:0,他引:3
SUBCLASSES of the three major classes of human immunoglobulins, IgG, IgA and IgM, are recognized: four of IgG are well defined1,2 and at least two of IgA3–5 and two of IgM6,7 have been demonstrated. This communication presents evidence for the existence of an antigenic heterogeneity in the heavy chains of IgD, which may also be indicative of subclasses within this class of immunoglobulin. 相似文献
3.
Abstract In the field, the population density (n) of crowded, living ramets of Salvinia molesta ranged from 2500 m ?2 in nutrient-poor water to more than 30 000 m?2 in nutrient-rich water. Biomass of living shoots (B) in some localities exceeded 600 gm?2 dry weight (150 tonnes ha?1 fresh weight) and shoots plus roots of living and floating dead material exceeded 1600 gm?2 dry weight (400 tonnes ha?1 fresh weight). The ultimate limit B= 105n0.5 suggested by previous authors was not exceeded. The highest n and smallest ramets occurred in nutrient-rich water and B was a linear function of n. Field experiments confirmed no effect of n, but a strong effect of nutrient availability, on ramet weight. In a glasshouse experiment, ramet populations did not ‘self-thin’ along the log log B-n trajectory of slope -0.5, which has been suggested for aclonal plants, but followed trajectories having slopes closer to +1.0 before halting at the ambient B-n limit. Nutrient concentrations in the plants increased during the experiment, causing ramet size to decrease and slopes of log log B-n trajectories to depart from +1.0 by amounts which reflected the degree to which nutrient concentration had changed. Under constant conditions, mean ramet size is expected to remain constant and log log B-n trajectories to travel in a straight line of slope +1.0 to the ambient B-n limit. This behaviour of salvinia, whose ramets consist of a single structural module, is contrasted with that expected of clonal plants whose ramets are made up of multiple structural modules. A logistic model explained the increases in n and biomass of living and dead ramets when ramets were assumed to have constant longevity, constant time to decay, and when both the B-n limit and size of ramets were dependent on nitrogen content of the plant. There was no indication that physiological integration within phenets halted production of new ramets when carrying capacity was reached and new ramets continued to be produced on top of older ramets. Rates of ramet mortality were equal to, and dependent on, rates of ramet natality. 相似文献
4.
Characteristics of the Wave of Depolarization Induced by Wounding in Bidens pilosa L. 总被引:2,自引:0,他引:2
JULIEN J. L.; DESBIEZ M. O.; DE JAEGHER G.; FRACHISSE J. M. 《Journal of experimental botany》1991,42(1):131-137
Heating locally the hypocotyl of Bidens pilosa L. elicits awave of depolarization. The mechanism of the wave has been investigatedby means of microelectrophysiological techniques. The amplitudeof the transmembrane potential variation induced by an extracellularion concentration change (K+, Na+, Ca2+, Cl) was thesame in the resting conditions as during the slow wave. At pH4.0, the amplitude of the slow wave was reduced by 56% comparedwith the control performed at pH 7.0. In the presence of theuncoupler CCCP, the slow wave was not observed. The Ca2+ -chelatorEGTA and the Ca22+ -channel blocker La3+ reduced, respectively,the amplitude of the slow wave by 78% and 68%. These resultsindicate the involvement of Ca2+ in triggering the slow wave.A transient modification of the electrogenic H+ pump activity(inactivation-activation) and of the transmembrane H+ flux inthe slow wave are discussed. Key words: Slow wave (of depolarization), wounding, electrogenic pump, calcium, Bidens pilosa L 相似文献
5.
Socio-genetic structure of mound-building mice, Mus spicilegus, in autumn and early spring 总被引:1,自引:0,他引:1
CHANTAL POTEAUX NICOLAS BUSQUET PATRICK GOUAT KRISZTIÁN KATONA CLAUDE BAUDOIN 《Biological journal of the Linnean Society. Linnean Society of London》2008,93(4):689-699
Mus spicilegus has become a popular biological model species in the last decade because of the evolutionary interest of its behavioural particularities (the building of mounds, bi-parental care and monogamous mating system). The genetic structure of M. spicilegus populations should reflect those life-history traits. Although many studies have reported on mound-building mouse populations in the field or in a semi-natural enclosure, only one used hyper variable genetic markers to assess parentage and social structure. In the present study conducted in Hungary, we analysed individuals from seven highly populous mounds in autumn with the set of loci used in a previous study. Our results confirmed that mounds are inhabited by juveniles from several parental units, but revealed population differences. In a capture–recapture field session in spring, we assessed genetic relationships between individuals after dispersal from the mounds, the other key moment of the life cycle of this species. The results indicate that the social structure at this moment reflects a transition phase between the large over-wintering groups and the monogamous pairs described later in the year. Social bounds forged during the long winter cohabitation may have lasting effects on social and genetic structure of this species. This scenario is discussed in respect of the available literature on this species as well as other species. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 689–699. 相似文献
6.
7.
ALEXANDRA HOUSSAYE JEAN‐CLAUDE RAGE NATHALIE BARDET PEGGY VINCENT MBAREK AMAGHZAZ SAID MESLOUH 《Palaeontology》2013,56(3):647-661
Abstract: Palaeophis maghrebianus belongs to the Palaeophiinae (Palaeophiidae). This snake subfamily is relatively poorly known, and it is mainly represented by disarticulated vertebrae and ribs and by a few vertebral segments. Its intracolumnar variability remains also poorly understood. The discovery of new isolated vertebrae and vertebral segments of Palaeophis maghrebianus in the Ypresian (Lower Eocene) Phosphates of Morocco enables us to provide a more detailed diagnosis of this species and to describe its intracolumnar variability. Moreover, the new material reveals that this species could reach gigantic size being, with Palaeophis colossaeus, one of the two longer palaeophiids. The microanatomical and histological analysis of some vertebrae illustrating diverse positions along the vertebral column reveals the presence of osteosclerosis, especially in the anterior and mid‐precloacal regions. The occurrence of this osseous specialization implies a role in buoyancy and body trim control in this taxon, which is considered a shallow marine dweller based on its anatomical features and geological data. Palaeophis maghrebianus also displays a dense vascular network suggesting a growth speed, and thus a metabolic rate, much higher than in the biggest extant snakes. 相似文献
8.
CLAUDE MONNIOT 《Zoological Journal of the Linnean Society》1994,110(1):41-51
New specimens from the Pacific coast of Panama provide the opportunity to redescribe Pyura lignosa Michaelsen, 1908. The status of this species and of three other similar pyurids ( P. vannamei nomen novum, P. cadamostoi sp. nov., and P. shiinoi Tokioka, 1949) is examined, and all four species are identified, described, and compared. 相似文献
9.
PHILIPPE GAUCHER PATRICK PAILLAT CLAUDE CHAPPUIS MICHEL SAINT JALME FATEMEH LOTFIKHAH MICHAEL WINK 《Ibis》1996,138(2):273-282
The Houbara Bustard Chlamydotis undulata is a polytypic species with three subspecies classified according size, colour and distribution: C. u. undulata, C. u. fuertaventurae and C. u. macqueenii. A comparative study of the male display behaviour of these three subspecies has shown similarities between C. u. undulata and C. u. fuertaventurae , whereas appreciable differences exist in the visual and auditory aspects of the display between C. u. undulata and C. u. macqueenii. These observations make the current taxonomy of Houbara Bustard questionable, particularly in view of the major importance of the sexual display in bird speciation processes. Furthermore, DNA analysis of the cytochrome b gene indicates the existence of a significant differentiation between the C. u. undulata and C. u. macqueenii populations. These findings indicate the need for a revision of the taxonomy of genus Chlamydotis which should separate the macqueenii and undulata populations at species rank. Until further investigations are completed, C. u. fuertaventurae should be kept as a subspecies of undulata since the courtship display is alike in both populations. 相似文献
10.