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101.
Chromosome numbers for 26 different species of the generaPiper, Peperomia andPothomorphe (Piperaceae) are reported. The basic chromosome numbers are 2n = 26, x = 13 (Piper, Pothomorphe) and 2n = 22, x = 11 (Peperomia), polyploid series are characteristic forPiper andPeperomia. Piper has the smallest chromosomes and prochromosomal interphase nuclei,Peperomia the largest ones and mostly reticulate to euchromatic nuclei.Pothomorphe is intermediate in both characters. The karyomorphological differences betweenPothomorphe andPiper underline their generic separation. Interspecific size variation of chromosomes occurs inPiper andPeperomia. Infraspecific polyploidy was observed inPiper betle. C-banding reveals different patterns of heterochromatin (hc) distribution between the genera investigated. The genome evolution is discussed. 相似文献
102.
103.
Multivariate statistical analysis has been applied to time series measurements of aerosol elemental composition from PIXE
analysis of filter samples, and principal components have been resolved that represent distinct particle types in an external
mixture in the atmosphere. In this study, it is argued that a combination of chemical and statistical analyses of the data
may be more powerful in determining chemical species in atmospheric aerosols than studies that employ mainly direct chemical
analysis of chemical species in unresolved mixtures of aerosol particle samples. Sulfur is generally associated with mineral
dust elements. It is reasoned that the association may represent sulfuric acid coatings on particles that can lead to mineral
dissolution and solubilization of significant amounts of aluminum, iron, and other metals.
Upon wet or dry deposition to the surface, the fluxes of these metals in biologically-available form may be sufficient to
affect primary productivity in the world ocean and cause ecological damage in lakes. As a consequence, the fluxes of biogenic
trace gases to the atmosphere may be changed, possibly leading to changes in the tropospheric concentration of ozone. The
inputs to lakes of soluble aluminum, which is toxic to fish, may be partly by deposition directly from the atmosphere, thus
not limited to leaching of soils by acid deposition. Human inhalation of soluble aluminum and other solulilized mineral metals
may account, in part, for the observed geographic pattern of deaths attributed to chronic obstructive pulmonary disease (COPD)
that show high rates in cities of the Western US and the southeast region, but low in most of the midwest and northeast. 相似文献
104.
105.
J. D. Paterson 《International journal of primatology》1996,17(4):585-611
I analyzed somatometric measurements from subsets of the Texas and Oregon transplanted troops of Japanese macaques(Macaca fuscata) to reveal secular changes in body size and shape. Body weights of the Texas population (N = 59) are lower than those of the
Oregon population(N = 49) and the founding population from Arashiyama. The adult weights of the Oregon population are significantly higher than the
founding population from Mihara. There are significant differences in adult circumferential measures and in skinfolds, which
are correlated with the increased weight of the Oregon macaques. The adult Texas macaques have longer limb segments in comparison
with the adult Oregon troop members, while the latter have significantly longer heads and trunks. Examination of the developing
morphological trends through regression analyses on the complete sample suggests distinctive growth patterns for each population.
Members of the Texas population start with smaller initial measurements but hold a steeper growth pattern for limb segments,
while the Oregon macaques start larger in most measures and show lower growth rates. I argue that these differences in both
somatometry and growth patterns are related to the differing climatic conditions under which the translocated macaques have
lived. This set of analyses supports the basic arguments for Bergmann’s rule and Allen’s rule. 相似文献
106.
107.
C.G. Rodriguez N. Makori M. A. Cukierski A. G. Hendrickx 《Journal of medical primatology》1996,25(2):122-132
Abstract: Formation of the definitive kidney in Macaca fascicularis embryos was investigated using light and electron microscopy. Appearance of the definitive kidney at stage 14 was indicated by the ureteric bud invading the metanephrogenic blastema. Glomerular capillaries originate from the connective tissue that surrounds the developing renal vesicle. At 46–100 days gestational age the more developed glomeruli show thinning of the capillary endothelium, thickening of the basal membrane, and presence of pedicels, suggesting a capability of renal function. 相似文献
108.
H. Schmidt A. Wichmann I. Lamprecht I. Zerbst-Boroffka 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1996,166(3):205-214
Anaerobic metabolism in the limnic annelid Hirudo medicinalis L. was investigated by direct and indirect calorimetry. During long-term severe hypoxia, the rate of heat dissipation was reduced up to 13% of the aerobic rate. At the same time, the rate of ATP turnover was reduced to about 30% of the aerobic rate, indicating that metabolic depression is an important mechanism to ensure survival of the leech during environmental anaerobiosis. Heat dissipation during hypoxia was monitored under two experimental conditions, favouring either concomitant hypocapnia (continuous N2 bubbling) or hypercapnia (self-induced hypoxia). The reduction in heat dissipation during hypocapnic hypoxia was less pronounced than during hypercapnic hypoxia, indicating that the different experimental conditions may influence anaerobic metabolism and the extent of metabolic depression. Biochemical analysis of known anaerobic substrates and endproducts provided the basis for indirect calorimetry during self-induced hypoxia. From changes in metabolites, the expected heat dissipation was calculated for initial (0–8 h) and long-term severe hypoxia (8–72 h). During the initial period, the calculated heat dissipation fully accounted for direct calorimetric determination. During long-term hypoxia, only 71% of the measured heat production could be explained from biochemical analysis of metabolites. Therefore, an additional unknown endproduct cannot be excluded, especially when anaerobic ammonia production and analysis of the carbohydrate balance are considered.Abbreviations
APW
artificial pond water
-
HPLC
high-performance liquid chromatography
-
fw
fresh weight
-
HP
heat production
-
HD
heat dissipation
-
MR
metabolic rate 相似文献
109.
DNaseⅠ超敏感位点的研究能够发现潜在的调控基因转录活化的位点,比较正常人外周血有核细胞,淋巴瘤细胞株P3HR1和人鼻咽癌低分化磷癌细胞株HOnE1和HNE2中Ha-ras-1瘤基因的DNaseⅠ超敏感位点发现,只有HONE1和HNE2细胞基因组中存在一个DNaseⅠ超敏感位点,位于第一个外显子上游0.37kb处,上述结果提示正常白细胞和P3HR1细胞中Ha-ras-1基因处于失活状态,而在鼻咽癌细胞基因组中则处于活化状态,它的活化可能与0.37kb处的DNA序列有密切的关系。 相似文献
110.
Abstract. Litter fall and decomposition in a Pinus halepensis forest was studied in order to help understand nutrient cycles in this ecosystem, threatened as it is by fire and tourism. The study was done over two years in an experimental forest stand at Cap des Pinar on Mallorca, Spain. The woodland area has not been disturbed for about 40 yr. Total litter fall amounted to 3.44 ton ha-1 yr-1 and 2.52 ton ha-1 yr-1 in the first and second year, and leaf fall to 2.00 ton ha-1 yr-1 and 1.93 ton ha-1 yr-1 respectively with a maximum in July. As to litter fall, there was a summer maximum for brown needles and kernels, a spring maximum for inflorescences and bud scales, and an autumn maximum for bark. Erratic maxima occurred for fall of green needles, cones and branches, linked to strong winds in winter. The total amount of litter mass on the forest soil reached 12.68 ton/ha: 5.75 ton/ha in the L organic horizon, 3.46 ton/ha needles, and 6.93 ton/ha in the F organic horizon. Weight loss from annual decomposition, measured using litter bags, was 18.1 % in year 1 and 26.8% in year 2. Over 365 days, an Olson (1963) decomposition rate of 0.045 %/day was found in year 1 and of 0.084 %/day for year 2. Decomposition half-time was 1529 for year 1 and 827 days for year 2. 相似文献