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1.
Summary In comparison to cassava grown in monoculture the root infection of cassava with vesicular-arbuscular mycorrhiza was increased by crop rotation with grain legumes in the field. This was also found when cassava was intercropped with legumes and fertilized. A possible specificity of mycorrhizal fungi to increase the yield of one species more than the other when grown in association, is discussed. 相似文献
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JessicaA. Maisano 《Zoological Journal of the Linnean Society》2002,136(2):277-313
Postnatal patterns of skeletal development, includingthe sequence of appearance of ossification centres and the distributionof sesamoids, appear to be highly conserved species-level phenomenain squamates. As such, they are a potential source of charactersfor phylogenetic inquiry. These patterns, from 21 species representing14 crown squamate clades, form the basis for two analyses. In thefirst, the sequence of postnatal skeletal events is coded as charactersusing the sequence unit approach. This analysis reveals that thesequence of postnatal skeletal events might be useful for determiningrelationships at or above the level of crown clades, but not amongthem. The second analysis utilizes discrete data from postnatalskeletal development, such as the presence/absence of sesamoidsand the number of secondary centres in epiphyseal cartilages. Thesediscrete data appear capable of recovering the deeper divergenceswithin Squamata, but evolve too slowly to be informative at thelevel of crown clades. Thus, patterns of postnatal skeletal developmenthave the potential to help illuminate relationships throughout thesquamate tree. Further progress in this area will require the examinationof additional squamate species, the exploration of alternative codingschemes for developmental sequences, and comparable postnatal datafor Sphenodon . © 2002 The Linnean Societyof London, Zoological Journal of the Linnean Society, 2002, 136 ,277−313. 相似文献
5.
Esteban E. Sarmiento 《International journal of primatology》1988,9(4):281-345
Observations on the behavior of living hominoids show generic differences in the use and posture of the wrist joint. Both
orang-utans and hylobatids usually use the wrist in suspensory behaviors. However, orang-utans emphasize markedly adducted
and flexed wrist postures, while hylobatids emphasize violent forearm and wrist rotation. African apes, especially the gorilla,
use the wrist more frequently than other hominoids for terrestrial quadrupedal weight-bearing. Humans use the wrist less frequently
for supportive purposes than do other hominoids. These behavioral differences correspond to structural specializations in
the proximal carpal joint of each of the hominoid genera. Although each of the hominoid genera has apparently modified its
proximal carpal joint best to serve its characteristic behaviors, all hominoids share a unique proximal carpal joint that
permits approximately 160ℴ of forearm rotation. The hylobatid proximal carpal joint is specialized in exhibiting a marked
development of those structures limiting forearm rotation, but it is in most respects the least derived— that is, closest
to the nonhominoid anthropoids. Chimpanzees show a proximal carpal joint that is more generalized than those of the other
great apes but more derived than that of hylobatids. The human and gorilla proximal wrist joints, on the other hand, show
marked modifications for weight-bearing in terrestrial behaviors. Orang-utans have the most derived proximal carpal joint,
which in many respects parallels that of the slow-climbing nonhominoid primates. The comparative anatomy and structural specializations
of the wrist joint support (a) an early divergence of hylobatids from the common hominoid stock, (b) a common ancestry for
gorillas and humans separate from the other hominoids, and (c) a long independent evolutionary period for orang-utans since
their divergence from the common hominoid stock, or one that was marked by strong selection pressures for wrist specializations.
Unfortunately, the generalized condition of the chimpanzee’s wrist joint and the very derived condition of the orang-utan
wrist provide uncertain evidence as to which of the two was first to diverge from the common hominoid stock. Identification
of hominoid wrist specializations as reflecting real phylogenetic relationships or parallelisms depends on how well the phytogeny
inferred from wrist morphology accords with those arrived at from the study of other systems. 相似文献
6.
R. Chima Wokocha 《Plant and Soil》1988,106(1):146-148
Populations of viable sclerotia ofSclerotium rolfsii were highest in soil in a field in which tomato was planted for three successive years before sampling and in one in which
tomato followed groundnut in the 2 years prior to this study. The lowest sclerotial numbers were recorded in fields in which
groundnut followed maize or in which maize or sorghum was the last crop before sampling. 相似文献
7.
Susanna T. Y. Tong 《Plant Ecology》1988,79(1-2):65-74
The plant-environment relationships in a range of matorral communities, having different rainfall conditions in semi-arid lowland habitats in Murcía, S.E. Spain, were examined using the non-metric multidimensional scaling ordination technique. Hypotheses on floristic variations were derived based on an interpretative strategy which involved a site configuration rotation, followed by stepwise multiple regression analysis. An environmental data set was used to isolate variables associated with site co-ordinate trends. Results showed that floristic variation in these communities was mainly determined by aspect induced radiation receipt. Besides, most environmental trends in the study areas were found to be oblique to original site ordination axes and configuration rotation seemed to be a prerequisite in quantitative interpretation. The interpretative strategy introduced in this study was effective. It enhanced straightforward, quantitative and objective interpretation whereby inductive inferences on environmental trends could be readily formulated.Abbreviations ARAD
radiation receipt surrogate
- DEPTH
soil depth
- DISTURB
disturbance index
- NMDS
non-metric multidimensional scaling
- NUT
nutrient scalar
- SLOPE
slope angle
- TEXTIN
texture index 相似文献
8.
Summary The lymphoid organs of rosy barb (Barbus conchonius) and carp (Cyprinus carpio) were investigated for their phagocytic uptake of carbon, after its intraperitoneal injection. Carbon handling was similar in both species. It was first detected in the lymphoid organs at 30 min after injection. During the first day, carbon was phagocytized by macrophages situated in the spleen within the ellipsoids and in the red pulp. In head and trunk kidney, carbon was found in macrophages scattered throughout the haemopoietic parenchyma, and in cells lining the blood sinuses. In the spleen, macrophages replete with carbon left the ellipsoidal structures and formed aggregates with pigment-containing macrophages from day 6 onwards. In all lymphoid organs, almost all carbon was ultimately concentrated in the melano-macrophage centres. 相似文献
9.
Lars Olof Björn 《Physiologia plantarum》1984,60(3):369-372
Experiments by several authors on the effects of polarized light on phytochromemediated responses in fern gametophytes and in the green alga Mougeotia have earlier been interpreted as showing that the transition moment of phytochrome in the Pr form is parallel to the plasmalemma, but perpendicular to the plasmalemma for the Pfr form of phytochrome. It is now shown that the experimental results can be interpreted differently, and that they are also consistent with a chromophore rotation of about 30° (instead of 90°), as found for immobilized phytochrome molecules in vitro. Thus there is no evidence for a rotation of the whole phytochrome protein. For the gametophyte of Adiantum it is calculated that the Pr transition moment is inclined 17° to the plasmalemma, and the Pfr transition moment ca 50°, corresponding to an in vivo chromophore rotation of ca 33°; however, these values are very approximate. 相似文献
10.
Conidiation in Alternaria cichorii Nattras is reversibly stimulated by near ultraviolet radiation (NUV, ca 313 nm) and inhibited by blue light (ca 450 nm) and seems to be a mycochrome-mediated process. After induction with plane-polarized NUV, blue light polarized perpendicularly to the NUV was more effective in counteracting the induction than was blue light polarized parallel to the NUV. From this the conclusions are drawn that (a) both the blue-absorbing component (presumably a flavo-protein) and the PNUV of the mycochrome system are membrane-bound and that (b) the transition moment associated with blue light absorption in the presumed flavoprotein forms an angle of at least 53° with the transition moment associated with NUV absorption in PNUV . 相似文献