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991.
James C. Beck Howard L. Hosick Bruce A. Watkins 《In vitro cellular & developmental biology. Plant》1989,25(5):409-418
Summary We investigated the effects of conditioned media derived from mouse mammary fat pads on the proliferation of CL-S1 cells,
an epithelial cell line originally isolated from a preneoplastic mammary outgrowth line. Cell proliferation in vitro in serum-free
defined medium was compared to that in this medium conditioned using intact mammary fat pad pieces or isolated fat pad adipocytes.
Culture medium was conditioned by incubating the conditioning material in defined culture medium for 24 h at 37°C. Conditioned
medium induced CL-S1 proliferation as much as 10- to 20-fold above the minimal levels of growth in control cultures after
13 d of culture. The growth-stimulatory factor(s) had an apparent molecular weight of greater than 10 kDa. This growth-stimulatory
activity was both heat and trypsin stable. Because the role of adipose tissue is to store and release lipids, we next tested
whether lipids are released during medium conditioning. The lipid composition of the fat pad conditioned medium was characterized
using both thin layer and gas liquid chromatography. These lipid analyses indicated that the fat pad pieces released significant
amounts of fatty acids and phospholipids into the medium during the conditioning period. The free fatty acid composition included
both saturated and unsaturated molecules, and about 80% of the total fatty acids consisted of palmitate, stearate, oleate,
and linoleate. These same fatty acids were a structural component of the majority of phospholipid found in the medium. The
addition of palmitate or stearate to defined medium had no effect or was inhibitory for CL-S1 proliferation, depending on
the concentration used. Defined medium supplemented with oleate, arachidonate, or linoleate induced CL-S1 proliferation, and
the inhibitory effects of palmitate and stearate were overcome by addition of oleate and linoleate. These data indicate that
both unsaturated and saturated fatty acids are released from intact adipose cells of the mouse mammary fat pad and that fatty
acids can influence the growth of prenoplastic mouse mammary epithelium. Thus, unsaturated fatty acids, perhaps in conjunction
with other substances released simultaneously, are candidate molecules for the substances that mediate the effect of adipose
tissue on growth of epithelium.
This work was supported in part by a grant from the American Institute for Cancer Research; grant CA 46885 from the National
Institutes of Health, Bethesda, MD; and by State of Washington initiative 171. 相似文献
992.
A. J. P. Raat 《Aquatic Ecology》1989,23(1):67-72
In ten 0.1 ha drainable ponds O+ cyprinids were stocked to assess their impact on the aquatic community. Bream and roach were stocked in early June, 1986, and carp in early July, 1986. The ponds were drained mid November, 1986. The relationship between the fish community and its food resource was estimated in terms of production and consumption with use of the data on growth and mortality of the fish. The average gross production of the fish species in the ten ponds (48.4 kg during the experiment) was dominated by the carp (58.5%). A minimum estimate of the food consumption of the O+ cyprinids is 760 kJ.m–2. The average production of bream and roach was much lower than that of carp due to a higher mortality and a more specialized feeding pattern. The gross productions of carp, bream and roach in the ten ponds were not significantly related, although stomach analysis showed diet overlap between the carp and the bream. 相似文献
993.
A method is presented to study dynamics of plants that cannot be separated into individuals such as many grassland, salt marsh and tundra species. A virtual population is created by using a permanent transect line through the vegetation and individuals are defined as the branch segments distal to the intercept with the transect line. Addition and loss of individuals together with growth or shrinkage form the basis for constructing a size-structured transition matrix. A discrete-event simulation demonstrates that: 1) a virtual population of individuals grows at the same rate as the parent population; and, 2) size-structured transition matrices for a virtual population and parent vegetation have similar dominant and subdominant eigenvalues so a virtual population can be used to describe the dynamics of a parent vegetation.Dwarf birch, Betula nana L., was studied in the northern foothills of the Brooks Range, Alaska, by using photography to record branch intercepts along permanent transect lines. The distal branch segments constitute a virtual population of the parent vegetation. Transects were photographed in 1985 and again in 1986 and changes of branch segments were used to construct two transition matrices for shrubs with and without elevated fertilizer treatment. Analysis of the virtual populations suggests that although Betula nana may show increased branch growth with increased fertilizer, in the long run this shrub may decline in the tundra in response to such treatment. 相似文献
994.
J. Bonde 《BioControl》1989,34(2):275-287
Amblyseius barkeri (Hughes) fed onThrips tabaci (Lind.) at 25°C showed an average duration of 2.2, 0.8 and 3.2 days for the egg, larval and nymphal stages, with mortalities
at 1.0, 1.0 and 3.1%, respectively. Females represented 63% of the population and required multiple matings for optimal fertility.
The oviposition period was 20.3 days and the average oviposition rate 2.3 eggs per day. The intrinsic rate of increase was
0.22 per day. The expected life span was 29.6 days for ♀♀ and 27.4 days for ♂♂.A. barkeri ♂♂ and ♀♀ both consumed 3.3 nymphs of thrips per day (mean value for the feeding stages). The larva does not take up food.
In the absence of thripsA. barkeri was able to consume two-spotted spider mites,Tetranychus urticae (Koch), and their eggs, adult broad mites,Polyphagotarsonemus latus (Banks), and pollen of various plants. Cannibalism was observed when food was lacking. Certain morphological features, egglaying,
mating and predatory behaviour are described.
相似文献
995.
The influence of kairomones on the numerical response of the parasitoidTrioxys indicus against its hostAphis craccivora at its varying density was studied. The kairomones (applied as aqueous extract of the host) significantly enhanced the rate
of parasitisation and multiplication and the area of discovery of the parasitoid and also the K-values of mortality of the
host at all parasitoid densities introduced (1, 2, 4, 8, 12 and 16 parasitoids) into troughs having about 200 hosts. The sex-ratio
of F1 offspring decreased at lower parasitoid densities and remained more or less unchanged at higher parasitoid densities after
the application of kairomones. The present findings indicate that if kairomones are applied properly, the number of hosts
destroyed by a stimulated parasitoid will be about 200, twice the number reported earlier, thus fewer parasitoids will be
needed to regulate an estimated population of the hosts.
相似文献
996.
For analytical purposes bioluminescence can be used in three main ways: 1. luminescence measurement of bioluminescent system components isolated in vitro; 2. determination of luminous organisms' reaction to the in vivo test-action; 3. measurement of bioluminescence in marine ecological systems. The majority of the reports of this Symposium are dealing with the first two topics. The aim of our presentation is to draw attention to the third one. The possibilities of bioluminescent analysis are wider than its traditional scheme of applications in the laboratory, when the emitting system is withdrawn from a native source and is placed in a cuvette of the light measuring device. The reverse scheme is also possible, i.e. the device can be introduced into light emitting system such as a marine biocenosis–the community of the sea inhabitants–where we obtain a highly sensitive and rapid means of gaining the information on the vital activity of marine ecosystems, i.e. their spatial structure, rhythms, man's influence upon them, etc. The present communication will consider the possibilities of this form of bioluminescent analysis. 相似文献
997.
小麦幼嫩颖果中,果皮内侧发育出由内表皮与亚表皮组成的一薄层绿色组织。显微与亚显微结构观察表明,虽绿色层只接受到自然光照的1/4~1/8,叶绿体仍能正常发育,叶绿素含量与叶绿体数量均高出旗叶。大量胞间连丝联接相邻的绿色细胞,并在一定时期形成开放的胞间通道,显然有利于同化物的快速胞间运输。离体颖果饲喂~14CO_2试验证明,新合成的同化物从绿色细胞输向胚珠。绿色层产生的同化物可能通过合点端的珠心进入胚乳或通过珠孔直接汇聚到胚珠和分化中的原胚。 相似文献
998.
作者于1986年参加巴尔鲁克山真菌考察,并到阿尔泰山地、伊犁谷地、吐鲁番等地采得黑粉菌标本70余份,鉴定为8属36种,13种为我国新纪录,它们是石竹叶苔炭黑粉(Anthracoidea caryophylleae Latour.),卡里炭黑粉(Anthracoidea karii(Liro) Nannf.),范基灰黑粉(Anthracoidea vankyiNannfeldt),短柄草腥黑粉(Tilletia olida (Riess) Schr(?)t.),剪股颍条黑粉(Urocystis agrostidis (Lavrov.) Zundel),黑麦草条黑粉(Urocystis bo-livari Bubák & Fragoso),雀麦条黑粉(Urocystis bromi (Lavrov) Zundel),拂子茅条黑粉(Urocystis calamagrostidis (Lavrov) Zundel),茅香条黑粉(Urocystis hierochloae (Murashk) Vánky),尼氏条黑粉(Urocystis nevodo-vskyi Schwarzman),早熟禾条黑粉(Urocystis poae(Liro)Padw.& Khan),报春花条黑粉(Urocystis primulicola P Magn.),和泡斑黑粉(Ustilagopustulata (D.C.) Winter 相似文献
999.
本文研究了人胃低分化粘液性腺癌细胞MGC 80-3不同周期时相中ConA受体的分布与侧向运动。MGc 80-3细胞经同步化培养,用F-ConA标记。被标记细胞中G_1、S和G_2期呈不连续的分布,但它们之间又存在显著的差异。M期呈较均匀的强荧光分布(与其它时相细胞比较)。荧光漂白恢复方法测定ConA受体复合物侧向运动表明:各个周期时相之间不仅运动方式不同,而且运动速率也有显著差异。M期与G_1期主要表现出扩散型运动;而S期与G_2期表现为流动型运动。G_1期的扩散系数大干M期的;S期的流动速率大于G_2期的。但可动分子百分比以G_2期最高。这些结果表明了ConA受体的动力学性质。它受到细胞周期的调节。 相似文献
1000.
黑腹果蝇P转座因子研究 Ⅰ.我国黑腹果蝇的P-M测定及其地理分布 总被引:1,自引:0,他引:1
采用性腺败育(GD不育)作为标准检定方法。对我国20个地方的黑腹果蝇的P因子活性和细胞型进行了测定。结果表明我国北部沿海城市为Q型;南部沿海和内地皆为M型。各地的M品系所产生的GD不育能力各不相同,但表现出与地理位置相关的梯度变化。这一变化规律为研究我国黑腹果蝇的P因子起源及P和M品系的形成提供了重要的理论依据。 相似文献