铬对中国林蛙蝌蚪生长发育的毒性效应

为评价水域环境中铬元素对两栖动物幼体的急性毒性,将中国林蛙(Rana chensinensis)28～29期蝌蚪分别暴露于30～35 mg·L-1Cr(Ⅲ)6个不同浓度和10 ～ 45mg·L-1Cr(Ⅵ)6个不同浓度的水体中,分别在24、48、72和96 h统计蝌蚪的死亡率及半致死浓度(LC50).结果表明:暴露24、48、72和96 h,Cr(Ⅲ)对蝌蚪的LC50分别为34.09±1.06、33.47±0.65、32.58±0.11和(32.05±0.20) mg·L-1,安全浓度(SC)为(3.21±0.02)mg·L-1;Cr(Ⅵ)对蝌蚪的LC50分别为91.97±5.32、51.19±4.62、35.79±1.40和(28.81±1.87) mg·L-1,安全浓度(SC)为(2.88±0.19) rng·L-1.观察表明:Cr(Ⅲ)的急性毒性是通过与蝌蚪皮肤表面的分泌物结合后粘附在鳃部,导致呼吸障碍致死;而Cr(Ⅵ)的强氧化性可导致蝌蚪的表皮溃变,鳃部萎缩致死;另外,将28～29期蝌蚪暴露于安全浓度(SC)以下的含铬水体进行慢性实验,通过检测蝌蚪的体长、体重和完全变态时间显示,低浓度的Cr(Ⅲ)和Cr(Ⅵ)对蝌蚪的生长发育仍具有一定的抑制作用,并可导致畸型发生,其作用强度呈现剂量效应,但时间累积效应不规律.     

壬基酚对中国林蛙蝌蚪生长发育的毒性效应

为评价壬基酚对中国林蛙(Rana chensinensis)蝌蚪的急性毒性,将26～28期的中国林蛙蝌蚪暴露于浓度为0.05～0.5 mg·L-1壬基酚(NP)的水体中进行急性毒性试验.结果表明:24、48、72、96h蝌蚪的死亡几率与浓度对数的回归方程分别为y=8.4087χ 10.202、y=9.5104χ 11.745、y=10.284χ 12.498、y=10.619,χ 13.095;半数致死浓度(LC50)分别为0.24、0.20、0.19、0.17 mg·L-1;安全浓度(SC)为0.017mg·L-1;96h的LC0为0.14 mg·L-1.证明林蛙蝌蚪的死亡几率与一定范围的NP浓度呈线性正相关.为探讨低浓度壬基酚对中国林蛙蝌蚪生长发育的影响,将26期林蛙蝌蚪分别在100、60、30、10μg·L-1 NP的水体中连续暴露直至完全变态,并以3、0.3 μg·L-1雌二醇(E2)作为阳性对照,分别统计林蛙蝌蚪暴露于NP和E2,中20、40d和完成变态后幼蛙的体质量、全长以及从26期到完全变态所需的时间.结果表明,NP浓度在100 μg·L-1以下,对林蛙蝌蚪不能致死.100、10 μg·L-1NP与3 μg·L-1E2的效应相似,均可滞后蝌蚪变态时间,降低蝌蚪变态后幼蛙的体质量.说明NP浓度在100μg·L-1以下不直接损伤蝌蚪机体,但可以通过干扰内分泌活动影响林蛙幼体的生长发育.     

Studies on spore germination and growth of some mycorrhizal-associated basidiomycetes

Summary Aqueous extracts of Western Hemlock roots were tested for the ability to stimulate initiation of growth from carpophore tissue of certain mycorrhizal-associated fungi. Of numerous species tested, onlyRozites caperatus andInocybe napipes responded slightly to this treatment, initiating a feeble mycelial development from gill tissue fragments.To determine whether exogenous NAD or young, excised roots would stimulate the growth of certain mycorrhizal fungi, species ofAmanita, Tricholoma, andXerocomus were subcultured in a rich basal medium, with and without added NAD or excised tomato roots. Spore germination tests on mycorrhizal-associated species not previously subcultured were conducted in a similar fashion.Added NAD stimulated the growth ofLeucopaxillus amarus but inhibited development ofArmillaria zelleri. It was without pronounced effect on the other cultures. In the presence of excised tomato roots, growth of theLeucopaxillus species was also stimulated, butArmillaria zelleri was inhibited slightly andXerocomus chrysenteron almost completely. Both treatments were without essential effect on the other species tested.No positive results were obtained with either added NAD or excised tomato roots in the spore germination studies.     

A model for the crowding effect in the growth of tadpoles

Crowded tadpoles in a limited volume grow to divide into two groups, a normally growing group and a stunted group, even if there are a plenty of food. This phenomenon was found to be interpreted by a model involving a mutual inhibition of the growth among individuals. It was assumed that the growth curve of an individual was modelled by a Gompertz growth equation. Through mathematical analysis and computer simulation of the model, it was shown that the average growth rate of the group was a decreasing function of the population density and that the group segregated into two subgroups, a normally growing group and a stunted group in a certain range of density. A theoretical prospect that the population of normally growing group is proportionate to the volume of the aquarium was obtained.     

Residual effect of germination temperature on the growth of peas

Summary In Pisum sativum there is a marked difference in the final height of the plants depending on the temperature at which the seed is germinated. Significant differences were also found in such parameters as growth rate, node of first flower, seeds per plant, pods per plant as well as flowers per plant.     

Biological soil crusts determine the germination and growth of two exotic plants

In arid and semiarid ecosystems, the potential threats of exotic invasive species are enhanced due to increasing human activities. Biological soil crusts (BSCs), acting as arid ecosystem engineers, may play an important role in preventing the establishment of exotic invasive plants. Our goal was to examine whether BSCs could inhibit the establishment of probable exotic plant species originating from adjacent grasslands located along the southeast edge of the Tengger Desert. In our study, we investigated the effects of three BSC types (cyanobacteria, lichen, and moss crusts) under two disturbance conditions (intact and disturbed) on the establishment of two exotic plant species (Ceratoides latens and Setaria viridis) using indoor experiments. We found both negative and positive effects of BSCs on the establishment of the two exotic plant species. Compared with the disturbed BSCs, the germination percentages of C. latens and S. viridis were reduced by 54% to 87% and 89% to 93%, respectively, in intact BSCs. In contrast, BSCs significantly promoted the height growth and aboveground biomass of the two exotic plant species (p < .05) by enhancing the soil water and nutrient availability for the exotic plants. Our results confirm that BSCs strongly suppress the rapid expansion of exotic plant populations by inhibiting germination of seed with big size or appendages and have a weak inhibitory effect on exotic plant with small and smooth seeds. This may decrease the threat of propagation of exotic species. In the meantime, BSCs promote the growth of a few successful engraftment seedlings, which increased the beta diversity. Our work suggests that better understanding the two opposing effects of BSCs on the establishment of exotic plant species in different growth stages (germination and growth) is important for maintaining the health and stability of revegetated regions.     

酚类物质对中国林蛙蝌蚪生长发育的毒性效应

中国林蛙蝌蚪对水环境有极强的依赖性,水环境中的酚类物质可以通过中国林蛙蝌蚪的呼吸系统和皮肤进入其体内,影响蝌蚪的存活状况、生长发育和生理生化指标。因此中国林蛙蝌蚪可以用作监测水体环境的指示物种。从壬基酚、辛基酚和双酚A等酚类物质对中国林蛙蝌蚪生长发育的毒性效应进行阐述,为酚类污染物对两栖动物生长发育影响机理的深入研究奠定基础,为中国林蛙蝌蚪的生态保护和水环境监测提供科学依据。     

Effects of aluminium and low pH on growth and development in Rana temporaria tadpoles

Summary Rana temporaria tadpoles were raised to metamorphosis at 6 levels of pH (pH 3.6–6.5) and 2 levels of aluminium (800 and 1,600 g l^-1) at pH 4.4. Treatments involved both chronic and acute exposure to depressed pH. Decreasing pH reduced maximum body size and delayed metamorphosis. Growth was depressed and metamorphosis delayed by 800 g l^-1 Al, and several tadpoles died at foreleg emergence. At 1,600 g l^-1 Al, small tadpoles suffered arrested growth and development and eventually died, while larger tadpoles metamorphosed without delay, though at a very small size. There was no mortality among controls. The levels of pH and inorganic monomeric aluminium measured in the experiments were similar to field levels at a site in Scotland, and it is concluded that individual tadpoles will, in certain types of water body, be adversely affected by both acidity and aluminium. The impact of these factors on populations remains to be determined.     

The effect of light quality on the growth and development of in vitro cultured Doritaenopsis plants

The influence of light quality on growth and development of in vitro grown Doritaenopsis hort. (Orchidaceae) plants was investigated. Growth parameters like leaf and root fresh/dry mass and leaf area were highest with plants grown under red plus blue light emitting diodes (LEDs). Leaf length was greater with the plants grown under red LED. Carbohydrate (starch, sucrose, glucose and fructose) and leaf pigment (chlorophylls and carotenoids) biosynthesis of the plants was significantly increased in plants grown under red plus blue LEDs compared to red or blue LED and fluorescent light treatments. This study suggests that the production of quality Doritaenopsis plants is possible by culturing the plants in vitro under a mixture of blue plus red light sources.     

Carry-over effects of embryonic acid conditions on development and growth of Rana temporaria tadpoles

1. Conditions experienced during the early stages of development may have carry‐over effects on performance during later life. The egg laying period and embryonic development of temperate and boreal zone amphibians often coincides with peak acidity resulting from spring snow‐melt, but the effects of acid conditions during embryonic stage on subsequent performance are unknown. 2. We investigated the potential carry‐over effects of acidity during the embryonic stage on performance up to metamorphosis in the common frog (Rana temporaria) tadpoles. There were four combinations of acid (4.5) and neutral (7.5) pH treatments applied to the egg and larval stages in a factorial laboratory experiment. In addition, we studied the difference in embryonic and larval tolerance of acidity between two populations originating from circumneutral (pH 6.6) and acidic conditions (pH 4.8). 3. The effects of acid conditions during the embryonic stage were sublethal, as indicated by delayed development and reduced size. Under acid conditions, tadpoles that had been raised in neutral water as embryos at first grew more slowly than tadpoles raised under acid conditions as embryos. At metamorphosis, no effects of embryonic acidity were detectable indicating that tadpoles were able to compensate fully for the initial reduction in growth. 4. Acid conditions during the larval period had a strongly negative effect on survival, size and age at metamorphosis. The amount of food consumed was lower under acid conditions, suggesting that reduced food consumption was at least partly responsible for the negative effects. 5. Although the two populations differed in the length of larval period, there was no indication of a differential response to the treatments in any of the metamorphic traits studied. 6. These results suggest that, although moderate acid conditions during embryonic development affect growth and development negatively, this influence does not persist after conditions have returned to normal. However, even moderately acid conditions during the larval period may have a strong negative influence on survival and performance of the tadpoles.     

Relatedness and competitive asymmetry – the growth and development of common frog tadpoles

Individuals can compete either through direct interference or uptake of limiting resources. If competing individuals are able to recognize their relatives, relatedness of competitors may evoke kin selection, which favours relatively even resource share among relatives. Resource competition is often size-symmetric, i.e. proportional to an individual's biomass, while interference competition is asymmetric giving large individuals a disproportionate advantage over small individuals. Kin-selection is predicted to reduce the intensity of direct interference and competitive asymmetry, leading to increased mean and decreased variation in individual size. We tested these predictions by investigating the effects of relatedness on age and size at metamorphosis in the common frog Rana temporaria tadpoles in a laboratory experiment. We reared related (full- and half-sibs) and unrelated tadpoles of different sizes (small, large, small and large together) at two densities until metamorphosis. Relatedness had little effect on mean growth, but it reduced size variation, as measured with coefficient of variation. Furthermore, there was a significant interaction between relatedness and density in size at metamorphosis, so that relatives always grew better in lower density, but growth was less affected by density among unrelated individuals. This indicates that the effects of relatedness on tadpole performance may be context dependent. Initial size differences in the mixed size treatment evened out during the course of the experiment, and initially small tadpoles were able to compensate the early growth losses, although it took longer for them to reach metamorphosis. We conclude that although relatedness may have rather small effects on the growth and development of R. temporaria tadpoles, it increases the symmetry of resource share decreasing between-individual variation in size at metamorphosis.     

Studies on microspore development in liliaceous plants

In microspores of angiosperm plants, the period from the end of meiosis in microsporocytes unitl the first cell division may be considered as one cell cycle, and the division is polarized, resulting in the formation of two functionally different nuclei. InLilium longiflorum, the duration of the cell cycle was measured in some detail. Identification of individual stages was based on the correlation between bud length and developmental stage. The results showed that the process begins at a bud length of 24 mm and is completed about 15 days later, at a bud length of 58 mm. By autoradiography of cells cultured in the presence of³H-thymidine, approximate durations of the G₁, S, and G₂ plus M phases were estimated to be about 12, 2, and 1 days, respectively. A detailed cytological analysis of the transitions between the various microspore stages has revealed some convenient parameters which point to ghe progression of change during the interval.     

Studies on the growth and development in Spirogyra

The phototropic response of Spirogyra sp. filaments and its relation with the different phases of their diurnal movements were studied. The filaments rapidly responded to unilateral irradiation; curvature towards the light source began in their tip region but shifted down to more basal regions. However, this typical and steady phototropic curvature could be observed only in the GnSt phase of the diurnal movement. In the other phases competitive states between the phototropic movement and other kinds of movement were evident. Thus, from the results of our previous and present studies it is proposed that the diurnal movement of Spirogyra filaments is composed of various individual movements, including a phototropic one; among these movements there exists a certain balance determined by the culture conditions and the time of day, and the phototropic movement is relatively inferior to the other movements.Abbreviations Gn negative gravitropism - Gp positive gravitropism - Sh shrinking (spiralling) growth - St straight form of growth V=Tanaka et al. (1983)     

鹤望兰催芽与幼苗生长习性的研究

用95%H₂SO₄浸鹤望兰种子(1:10体积比混合)3-5min,能有效地除去种皮表层蜡质,疏松种皮,不损伤种子,缩短萌芽时间。1N NaOH处理效果次之。95%乙醇洗脱无明显效果。幼苗移栽前适当处理(代森锌700倍+0.02mg/LNAA浸泡1h)能有效地抵御病害,提高幼苗成活率。栽培基质以透水保湿多肥的酸性土最好。此外,遮阳(60%~80%)是幼苗安全越夏的重要条件。     

Studies on the growth and development of Oxalis latifolia

The growth and development of Oxalis latifolia was assessed on outdoor-grown potted plants raised from bulbs. Three main phases of growth appeared to be correlated with major physiological developments in the aerial and subterranean organs. Establishment (weeks 1 – 5) was characterised by a slow gain in plant dry weight accompanied by high relative growth rate (RGR) values for individual plant organs. The second phase of growth (weeks 6 – 12) was reproductive, as stolons grew and initiated bulbils at the apices. Bulbils had the capacity to produce their own shoot system and ultimately some primary bulbils supported secondary bulbils. Dry matter accumulation was in the order: bulbils > peduncles > leaves > petioles > stolons = roots > parent bulb. The RGR of individual plant organs declined together with the net assimilation (NAR) rates and the leaf area ratio of the shoots during the reproductive phase and beyond into the senescence phase (week 13 onwards). The results are discussed in relation to the problem of achieving weed control via cultural and herbicide treatments.     

The role of the sucrose transporter, OsSUT1, in germination and early seedling growth and development of rice plants

Using expression analysis, the role of the sucrose transporter OsSUT1 during germination and early growth of rice seedlings has been examined in detail, over a time-course ranging from 1 d to 7 d post-imbibition. Unlike the wheat orthologue, TaSUT1, which is thought to be directly involved in sugar transfer across the scutellar epithelium, OsSUT1 is not expressed in the scutellar epithelial cell layer of germinating rice and is, therefore, not involved in transport of sugars across the symplastic discontinuity between the endosperm and the embryo. OsSUT1 expression was also absent from the aleurone cells, indicating it is not involved in the transport of sucrose in this cell layer during germination. However, by 3 d post-imbibition, OsSUT1 was present in the companion cells and sieve elements of the scutellar vascular bundle, where it may play a role in phloem loading of sucrose for transport to the developing shoot and roots. This sucrose is most likely sourced from hexoses imported from the endosperm. In addition, sucrose may be remobilized from starch granules which are present at a high density in the scutellar ground tissues surrounding the vasculature and at the base of the shoot. OsSUT1 was also present in the coleoptile and the first and second leaf blades, where it was localized to the phloem along the entire length of these tissues, and was also present within the phloem of the primary roots. OsSUT1 may be involved in retrieval of sugars from the apoplasm in these tissues.     

密度对大树蛙蝌蚪生长发育和存活率的影响

种群密度效应主要表现在影响和调节种群的死亡率、发育速率、繁殖率以及扩散、迁移等反应种群数量动态的重要参数。分析密度对大树蛙蝌蚪生长发育和存活率的影响,有助于探究外界环境因子导致大树蛙种群密度迅速下降的作用机制。设置了15、20、25只/L和30只/L 4个密度组,测量大树蛙蝌蚪的尾长、体长、发育时间和存活率。结果表明,在15—30只/L范围内,密度升高显著降低了大树蛙蝌蚪尾长和体长的生长速率,减小其变态期的尾长和体长大小,其中与15只/L相比,20、25只/L和30只/L 3组蝌蚪的尾长分别降低了11.6%、11.8%和13.9%,体长分别降低了11.1%、9.5%和12.9%;随着密度的升高,大树蛙蝌蚪发育至跗蹠部伸长期和前肢伸出期的所需时间显著延长;大树蛙蝌蚪生长后期的存活率随密度升高显著降低,但密度对蝌蚪生长早期的存活率影响不显著。因此,密度升高可显著减小大树蛙蝌蚪的尾长和体长、延长发育时间和降低其生长后期的存活率,可能影响大树蛙蝌蚪变态后的适合度。