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21.
Alessandro Terrinoni Carmen Di Franco Patrizio Dimitri Nikolaj Junakovic 《Journal of molecular evolution》1997,45(2):145-153
The intragenomic location of the elements of the I, G, jockey, F, and Doc transposon families has been studied by the Southern
blot analysis, in 12 laboratory Drosophila melanogaster stocks. Elements located in euchromatin, heterochromatin, and on the Y chromosome are identified, and their stability has
been assessed by comparing the autoradiographs detected in different stocks and analysis of individual flies. Evidence is
shown suggesting that preferential location in euchromatin or heterochromatin and the distribution within heterochromatin
are distinctive of transposon families. Elements located in heterochromatin can be unstable. These results are discussed in
the context of the relationship between transposable elements and the host genome.
Received: 21 August 1996 / Accepted: 24 March 1997 相似文献
22.
氮磷对污水净化中藻类叶绿素含量的影响 总被引:3,自引:1,他引:2
在室内模拟生物净化槽中比较研究了氮磷对污水中藻类叶绿素含量和污水净化的影响。污水中磷含量均为7mg/L左右,氮含量分别为77.4、44.4、24.8和13.5mg/L,结果发现TN/TP=77.4/7.01mg/L组,污水经7d净化,藻类叶绿素含量最高,污水净化效果较好。四个实验组比较,叶绿素含量随TN/TP比例的上升而上升,呈显著正相关。 相似文献
23.
Diazepam in vitro produced a concentration-dependent increase of membrane fluidity in crude synaptic membranes from rat hippocampus, but not cerebellum. Similar effects were obtained with higher concentrations of Ro 15-1788 and PK 11195, while zopiclone was completely inactive. In vivo acute treatment with diazepam and Ro 15-1788 gave results similar to those in vitro. The specific benzodiazepine antagonist also significantly increased membrane fluidity and was not able to reverse diazepam's effect. The data are discussed in terms of a possible role of protein kinase inhibition by the drugs not mediated by the 'central' or 'peripheral' type of benzodiazepine receptors. 相似文献
24.
Summary Cells ofChlamydomyxa montana Lankester photosynthesize within a cyst under bright light and ingest diatoms in an excysted amoeboid form during periods of low light intensity. Cyst cell walls are partially comprised of cellulose and vary in thickness. The cells are multinucleate and intracellular bacteria are closely associated with the nuclei. A pair of centrioles is also present adjacent to individual nuclei. Chloroplasts are numerous and thylakoids are generally organized into bands of three. No endoplasmic reticulum was found surrounding the plastids, nor was a complete girdling lamella ever observed within.C. montana chloroplasts appear to be its own but this protist does not precisely fit into an algal class. 相似文献
25.
Interactions between a naturally-collected algal species and strains of bacteria with which it was closely associated were examined under controlled conditions. Three strains of bacteria, Pseudomonas, Xanthomonas and Flavobacterium, were isolated from Oscillatoria. These bacteria were grown in combination with axenic cultures of the Oscillatoria culture as well as with several additional algal species. Oscillatoria growth was stimulated by all of the bacteria, but other algal species varied in their response. Some were stimulated, but others were inhibited or unaffected by exposure to the bacterial strains. There were also observations indicating that some algae may be able to develop resistance to antagonistic bacteria. These data suggest that succession and dominance of individual algal species may be influenced by interactions with bacteria. 相似文献
26.
The unitary nature of the mitochondrion and the characteristic flattened finger-like morphology of the cristae were demonstrated in the Cryptophyceae. Hemiselmis rufescens contained an unbranched vermi-form mitochondrion in contrast to the variously branched complex, comprising an interconnected peripheral and central reticulum, in Chroomonas sp. and strains of Cryptomonas. The systematic value of the shape and distribution of the mitochondria in the examined genera was suggested. 相似文献
27.
32P was applied to a Laminaria digitata thallus and the pattern of 32P phosphorylated compounds was studied, as a function of time, in the different tissues involved in translocation, i.e. source, pathway and sinks. The results showed that, 3 hours after absorption by the uptake region (lamina), the bulk of the radioactivity was incorporated into organic compounds (70 to 80% of total 32P taken up), hexose monophosphates being the heaviest labelled. Further change in that region was marked by an accumulation of 32P in the inorganic pool (65 to 70% after 13 days). Conversely, the 32P pattern in the medulla of the stipe, which initially showed a similar pattern to the uptake region, did not vary during translocation. The pattern of 32P distribution into sinks (growing stipe peripheral tissue or hapteron) leads to accumulation of the radioactive element in inorganic and acid-insoluble fractions. These results are discussed in terms of comparative distribution of 32P in the different parts of the thallus and suggest that phosphate moves as Pi in that alga.Abbreviations TCA
trichloroacetic acid
- Po
organic phosphate
- Po sol
acid-soluble organic phosphate fraction
- Po insol
acidinsoluble organic phosphate fraction
- Pi
morganic phosphate fraction
- P lip
lipidic phosphate
- Np
protein nitrogen
- ATP
adenosine triphosphate
- ADP
adenosine diphosphate
- PEP
phosphoenolpyruvic acid
- PGA
phosphoglyceric acid
- G-1-P
glucose-1-phosphate
- G-6-P
glucose-6-phosphate
- UDPG
uridine diphosphoglucose 相似文献
28.
Aderopo Akinsoji 《Plant Ecology》1991,92(2):181-185
Bark microflora of 12 rainforest trees were examined. Crustose, foliose, and fruticose forms of lichens were observed. Bacillus sp., Erwinia sp., Micrococcus sp., Proteus sp., and Pseudomonas sp. were the five genera of bacteria recorded while three genera of Cyanobacteria; Entophysalis, Gleocapsa and Stigonema were observed. In the algal division, three genera of Chlorophyta found are Chlorococcum, Pleurococcus and Physolinum. Only one diatom, Cocconeis sp. was present on just one tree. Most of the epiphytic microflora found are mainly terrestrial and their spores might have been deposited on the barks by air, or dust-currents. While moisture is regarded as the most critical factor in growth of bark microflora, other factors like texture of the bark, insolation and especially chemical characteristics of the barks may play a key role in occurrence and distribution of micro-organisms on them. 相似文献
29.
Middle Ordovician reefs of Norway 总被引:1,自引:0,他引:1
TOM L. HARLAND 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1981,14(3):169-188
The Middle Ordovician reefs of Norway were the first to develop in the western part of the Balto-scandian epicontinental sea and are the earliest coral-stromatoporoid reefs so far reported in Europe. Small patch reefs in the Steinvika Limestone, Langesund-Skien district, consist mainly of algae, echinoderms, corals and stromatoporoids. Bryozoans, molluscs, arthropods and brachiopods are also present. The reefs developed on pelmatozoan-rich substrates and are organically zoned, consisting of a pioneer community of stemmed echinoderms and sheet algae, a high-diversity intermediate community dominated by fasciculate corals and a low diversity climax community of massive corals and stromatoporoids. These communities are interpreted as the seral stages of an autogenic ecological succession. Small patch reefs are also present in the laterally equivalent Mjøsa Limestone, Toten and Nes-Hamar districts. These are organically very similar to those in the Steinvika Limestone and developed in an identical way. A large complex, consisting of several reefs, is also present in the Mjøsa Limestone. Unlike the reefs elsewhere, which developed within shallow inshore areas, this complex developed at the outer edge of the inshore shelf. The outstanding feature of the complex is the main reef forming the offshore limit which is totally dominated by stromatoporoids and lacks a sequential development. This is due to the influence of the harsher environment at the shelf edge. 相似文献
30.
Kurt Schwarz 《Plant Systematics and Evolution》1979,131(3-4):193-209