A bioreaction–diffusion model for growth of marine sponge explants in bioreactors

Marine sponges are sources of high-value bioactives. Engineering aspects of in vitro culture of sponges from cuttings (explants) are poorly understood. This work develops a diffusion-controlled growth model for sponge explants. The model assumes that the explant growth is controlled by diffusive transport of at least some nutrients from the surrounding medium into the explant that generally has a poorly developed aquiferous system for internal irrigation during early stages of growth. Growth is assumed to obey Monod-type kinetics. The model is shown to satisfactorily explain the measured growth behavior of the marine sponge Crambe crambe in two different growth media. In addition, the model is generally consistent with published data for growth of explants of the sponges Disidea avara and Hemimycale columella. The model predicted that nutrient concentration profiles for nutrients, such as dissolved oxygen within the explant, are consistent with data published by independent researchers. In view of the proposed model’s ability to explain available data for growth of several species of sponge explants, diffusive transport does play a controlling role in explant growth at least until a fully developed aquiferous system has become established. According to the model and experimental observations, the instantaneous growth rate depends on the size of the explant and all those factors that influence the diffusion of critical nutrients within the explant. Growth follows a hyperbolic profile that is consistent with the Monod kinetics.     

Efficient plant regeneration from seedling explants of two commercially important temperate eucalypt species–Eucalyptus nitens and E. globulus

A reliable and reproducible method for plant regeneration in vitro of two important temperate eucalypts, Eucalyptus nitens and E. globulus, has been developed which utilises seedling explants. Highly regenerative callus was obtained from individual cotyledon and hypocotyledon explants of both species following cultivation on Murashige and Skoog’s (MS) basal nutrient medium supplemented with 30 g l⁻¹ sucrose, 5–10% (v/v) coconut water, 0.8% agar, 1 mg l⁻¹ -naphthalene-acetic acid (NAA) and 0.5 mg l⁻¹ N⁶ benzylaminopurine (BAP). Shoot differentiation was observed 7–8 weeks after transfer of callus onto regeneration medium containing 0.5 mg l⁻¹ NAA and 1 mg l⁻¹ BAP. In a few instances, direct shoot regeneration occurred without an intervening callus phase in both species. The frequency of plant regeneration was higher for callus derived from hypocotyl segments (30–35%) compared to cotyledonary explants (20–25%) though the average number of shoots per cotyledonary explant was generally higher than for hypocotyl explants. Somatic embryos were observed occasionally in E. nitens, arising from the surface of organogenic callus. Organised structures closely resembling somatic embryos were also observed in E. globulus. Regenerated shoots (30–40%) of both species could be rooted in modified MS media containing indole-3-butyric acid (IBA) and plantlets were successfully transferred to soil.     

粉美人萱草的快繁技术和大田种植

以粉美人萱草(Hemerocallis fulva cv. ‘Fenmeiren’)的花茎为外植体进行离体培养, 该研究成功建立了粉美人萱草组培快繁技术。结果表明, 6月获得的外植体用浓度为15% (v/v)的次氯酸钠溶液消毒8分钟, 外植体存活率达95%; 最佳增殖培养基为MS+1.0 mg·L^-1 6-BA+0.004 mg·L^-1 TDZ+0.1 mg·L^-1 NAA, 培养30天后, 月增殖系数达2.9; 壮苗培养基为MS+0.1 mg·L^-1 6-BA+0.1 mg·L^-1 IBA, 在该培养基中, 组培苗不再分化, 长势健壮; 最佳生根培养基为1/2MS+0.4 mg·L^-1 IBA+20 g·L^-1蔗糖, 生根率达95%; 移栽基质采用珍珠岩:草炭=1:2 (v/v), 通过精细化管理, 成活率可达85%, 出圃合格率为75%。目前已实现规模化繁殖, 并生产组培苗2.0×10⁵株, 大田种植表现良好。     

四数九里香组织培养(简报)

以四数九里香新生带腋芽茎段为外植体,研究取材时期、6-BA浓度及生长素种类对外植体生长的影响,探讨不同浓度活性炭对外植体褐化的影响。结果表明,四数九里香组织培养适宜的取材时期为4月;外植体腋芽诱导率在6-BA浓度为2.5 mg·L^-1时表现较高;IBA是较适宜外植体生长的生长素;活性炭浓度为1.5 g·L^-1可有效减轻外植体褐化;组织培养适宜的启动培养基为MS + 6-BA 2.5 mg·L^-1 + IBA 0.1 mg·L^-1 + GA3 0.3 mg·L^-1 + 活性炭1.5 g·L^-1。     

Shifts in thermoregulatory patterns with pregnancy in the poikilothermic mammal—The naked mole-rat (Heterocephalus glaber)

1. 1. The naked mole-rat (Heterocephalus glaber) is a poikilothermic mammal. During gestation metabolic shifts that differ from both mammalian and reptilian thermoregulatory patterns occurred.

2. 2. Body temperature was directly dependent on ambient temperature. At low ambient temperatures the temperature differential (T_b − T_a) was approximately 3°C, whereas at higher ambient temperatures the temperature differential diminished.

3. 3. In early pregnancy (prior to week 3) oxygen consumption at low ambient temperatures was greater than that of non-reproductive animals. A maximal metabolic rate (3.2 ± 1.0 ml O₂ . g⁻¹ . h⁻¹) occurred at an ambient temperature of 27°C. Thereafter the endothermic pattern of metabolism with increasing ambient temperatures was evident. Oxygen consumption decreased with increasing ambient temperature to minimal rates of 1.2 ± 0.1 ml O₂ . g⁻¹ . h⁻¹ over the ambient temperature range of 31–34°C.

4. 4. Oxygen consumption in late pregnancy (1.8 ± 0.1 ml O₂ . g⁻¹ . h⁻¹) was not correlated with ambient temperature over the entire ambient temperature range measured (24–36°C).

5. 5. Differences in thermoregulation in early and late pregnancy may be attributed to different rates of heat loss as a consequence of (a) changes in surface area and body mass or (b) vascular changes. Furthermore the thermoregulatory changes in late pregnancy may indicate that maximal overall metabolic capacity had been reached, for peak resting metabolism (expressed per animal rather than per gram body mass) in early pregnancy was similar to observed metabolism in late pregnancy.

6. 6. The dissociation of metabolism from both ambient temperature and body temperature in late pregnancy could confer an energetic advantage to this arid dwelling underground inhabitant; for it may enable the breeding female to partition a greater portion of available energy into reproduction.

多鳞四须鲃耗氧率、排氨率和窒息点的初步研究

控制水温在(20±0.5)℃条件下,采用Winkler法和奈氏试剂法分别测定水中的溶氧含量和氨氮含量,通过比较流水呼吸室进、出口水中的溶解氧和氨氮含量之差以确定多鳞四须鲃(Barbodes schwanenfeldi)的耗氧率、排氨率及窒息点.结果表明,多鳞四须鲃耗氧率随体重增加而减小,关系式为Y=0.24X^-0.09(R²=0.9028);随放养密度的增大而减小,关系式为Y=-0.029X+0.3301 (R²=0.9291).排氨率随体重的增加而减小,关系式为Y=-0.0008X+0.2433 (R²=0.9817);随放养密度的增大而增加,关系式为Y=-0.050X+0.4979 (R²=0.9889).多鳞四须隹巴晚间(18:00～4:00)的耗氧率明显高于白天(6:00-1:00),排氨率则相反,白天的排氨率相对较高,表明多鳞四须鲃巴属于"昼伏夜出"型鱼类.多鳞四须啬巴的窒息点为1.2572mg·L^-1,耐氧性较差.     

Influence of acclimation and determination temperature on the oxygen consumption of the brain in two species of anurans

1. 1. The effects of sudden changes by increasing or decreasing the measurement temperature on the oxygen consumption of the brains of Bufo arenarum and Leptodactylus ocellatus were determined.

2. 2. The experiments were carried at in vitro at temperatures which range from 4 to 37°C. The brain was oxygenated and stabilized for 20 min at each of the temperatures to which it was subjected before oxygen consumption measurements were made.

3. 3. A theoretical curve representing the variation of oxygen consumption with temperature was calculated according to the following exponential relationship; for Leptodactylus ocellatus y = 0.408 × 1.07^x and for Bufo arenarum y = 0.389 × 1.065^x.

4. 4. These results were compared with the brain oxygen consumption of animals acclimated to different temperatures, whose oxygen consumption was measured at a fixed temperature. Only Leptodactylus ocellatus had a significantly lower oxygen consumption in a high range of temperatures, indicating thermal compensation, probably to save metabolic reserves.

5. 5. No deterioration of the brain tissue was observed, as several passages from high to low temperatures in the range of 20°–30°C, showed a reversible oxygen consumption in acclimated and non-acclimated Bufo arenarum and Leptodactylus ocellatus.

Growth of the sponge Pseudosuberites (aff.) andrewsi in a closed system

Explants of the Indo-Pacific sponge Pseudosuberites aff. andrewsi were fed with the microalgae Chlorella sorokiniana and Rhodomonas sp. It was microscopically observed that these algae were ingested and digested by the sponge cells, suggesting that they were consumed by the sponges. The algae were further used for two growth experiments with five explants of P. aff. andrewsi and four explants of P. andrewsi. Growth was measured as the increase in projected body area. The explants showed considerable growth (up to 730% in 54 days for P. aff. andrewsi and up to 680% in 22 days for P. andrewsi), which is much higher than previously reported growth rates for sponges. Growth started after a stationary phase of 5–20 days in which the projected body area did not increase. The growth of P. aff. andrewsi appeared to be linear and was inhibited at the end of the experiment. Two explants of P. andrewsi showed exponential growth instead of linear growth. Hence, no general statements about the growth kinetics of these sponges can be made at this time. However, the high growth rates found in this study suggest a promising future for cultivation of sponges in closed systems.     

典型林区水分氢氧稳定同位素在土壤-植物-大气连续体中的分布特征

土壤-植物-大气连续体(SPAC)中水循环是水文学和生态学研究的重要内容,氢氧稳定同位素在不同水体中组成特征的差异可以指示水分循环过程.本研究通过分析成都平原区亚热带常绿阔叶林中降水、土壤水、植物水的同位素组成,探讨SPAC系统中水分的氢氧稳定同位素演化特征,揭示区域水循环不同界面过程.结果 表明:研究区雨季大气降水线...     

大花银莲花愈伤组织诱导及再生体系的建立

为建立野生大花银莲花(Anemone silvestris)组培再生体系,分别以无菌苗上、下胚轴、叶片和叶柄为外植体,探讨不同浓度植物生长调节剂对不同外植体的愈伤组织诱导、不定芽分化、增殖与生根的影响。结果表明, 4种外植体均可诱导出不定芽,其中上胚轴诱导效果最佳,其在1/2MS+2.0mg·L^–1 6-BA+0.1mg·L^–1 NAA培养基中诱导率最高,为86.67%;最适增殖培养基为1/2MS+1.0mg·L^–1 6-BA+0.05mg·L^–1 NAA,增殖系数为3.67;最佳生根培养基为1/2MS+0.3mg·L^–1 IBA,生根率为100%;在草炭:蛭石=2:1(v/v)的栽培基质中,组培苗的移栽成活率最高,为98.33%。该研究有效解决了野生大花银莲花在园林及药用生产上的种质资源紧缺难题,为工厂化育苗提供了技术支撑。     

Manipulation of environmental variables and the effect on the growth of Haliclona sp.: Implications for open-water aquaculture

We examined how the physical environment influences the growth and survival of an undescribed Haliclona species. To determine the influence that water movement, light and sediment had on the sponge, explants of Haliclona sp. (approximately 8 cm³ in size) were transplanted into manipulated microenvironments at Hamelin Bay on the west coast of Western Australia near Perth. The sponge is typically found under limestone ledges and appears to have distinct limits on the microenvironment in which it is found. A three-factor orthogonal design was used to manipulate levels of light, water flow and sedimentation. Each factor had two experimental levels, creating environments with high and low water movement, high and low light, and upward and downward orientations to control sediment levels. The survival of explants was high (100%). However, all explants showed a regression in weight. Explants transplanted on to the underside of horizontal surfaces (downward orientations) demonstrated significantly less weight loss (P = 0.023), which was attributed to lower sediment exposure. Light and water movement did not significantly influence the sponge's growth.     

Effects of boundary layer conductance on substomatal pressures of carbon dioxide

Abstract. Gas exchange measurements were made on single leaves of three C₃ and one C₄ species at air speeds of 0.4 and 4.0 m s⁻¹ to determine if boundary layer conductance substantially affected the substomatal pressure of carbon dioxide. Boundary layer conductances to water vapour were 0.4 to 0.5 mol m⁻² s⁻¹ at the lower air speed, and 1.2 to 1.5 mol m⁻² s⁻¹ at the higher air speed. Substomatal carbon dioxide pressures were about 5 Pa lower at low boundary layer conductance in the C₃ species, and about 3 Pa lower in the C₄ species when measurements were made at high and moderate photosynthetic photon flux densities. No evidence of stomatal adjustment to altered boundary layer conductance was found. Photosynthetic rates at high photon flux densities were reduced by about 20% at the low air speed in the C₃ species. The commonly reported values of substomatal carbon dioxide pressure for C₃ and C₄ species were found to occur only when measurements were made at the higher air speed.     

2004年东海原甲藻赤潮爆发的现场调查和分析

2004年4～5月对东海赤潮高发区开展了赤潮原因种的大面观测并对期间爆发的特大赤潮进行跟踪调查,在56个站位采集了171份样品。表层东海原甲藻(Prorocentrum donghaiense)变化范围为2.5×10³～6.0×10⁷cells·L^-1,最大值出现在122.94°E,30°N的rb12A站;中层东海原甲藻变化范围为1.0×10³～5.32×10⁶cells·L^-1,最大值出现在rf40站。从水平分布看,东海原甲藻呈不均匀分布,从垂直分布看,赤潮爆发前原甲藻细胞在水体中层密集,大量增殖后上升到表层,爆发赤潮。     

Oxygen concentration profiles and exchange in sediment cores with circulated overlying water

SUMMARY. 1. The overlying water of intact sediment cores was constantly stirred with an impeller at a rate sufficient to mix turbulently the water column and maintain the diffusive boundary layer at a determined thickness. The system allowed standardization of water circulation in laboratory sediment core experiments.
2. Both oxygen concentration and oxygen penetration depth in the sediments decreased, the former by 70% and the latter from 4.2 mm to 2.0 mm, when the overlying water was not stirred for 24 h, as measured with oxygen microelectrodes in a lake sediment core.
3. Oxygen profiles measured in sediment cores in the laboratory were similar to those measured in situ when the overlying water was stirred with an impeller at such a rate that a similar thickness of the diffusive boundary layer at the sediment-water interface developed in the laboratory as that in situ.
4. Sediment oxygen consumption was calculated from: (1) measured oxygen profiles in the diffusive boundary layer and the molecular diffusion coefficient for oxygen in water; (2) the measured oxygen decrease in the top of the sediments and the estimated diffusion coefficient in the sediment; and (3) by oxygen differences in the overlying water after incubation of sediment cores.     

3种抗褐化剂影响水曲柳体胚发生的生理分析

水曲柳体胚发生过程中往往伴随褐化现象的产生,并且大多体胚生长在褐化的外植体上,为解析外植体褐化和体胚发生之间的联系,本研究通过在培养基中添加PVP（聚乙烯毗咯烷酮）、L-Glu（L-谷氨酸）和AgNO₃（硝酸银）,探究其对外植体褐化、体胚发生和生理生化的影响。研究结果表明：（1）低浓度（0.1、0.5 g·L^-1）PVP和100 mg·L^-1 L-Glu处理加剧了外植体褐化,但显著促进了体胚发生,并且体胚发生率高达60%以上（分别比对照组提高了6.59%、24.08%和22.88%）;（2）200 mg·L^-1 L-Glu处理有效降低了外植体褐化,褐化率为68.11%（相比对照组降低了5.83%）,但是体胚发生率降低,其发生率为46.32%（相较于对照组降低了22.8%）;（3）3种抗褐化剂处理后外植体细胞内的多酚氧化酶活性（PPO）和超氧化物歧化酶（SOD）活性均低于对照组,过氧化物酶（POD）活性和丙二醛（MDA）含量均高于对照组。因此,研究表明低浓度的抗褐化剂可以促进体胚发生,在这个过程中涉及到POD活性升高和MDA含量增加。本研究为解析水曲柳体胚发生伴随外植体褐化的生物学机理以及水曲柳体胚高频发生提供理论依据。     

Morphometry of some structural parameters affecting oxgyen diffusion in body trunk red muscle at different sizes of a tilapia, Oreochromis niloticus

Morphometric measurements were carried out on some of the structural parameters affecting oxygen diffusing capacity in red muscle of 15 specimens of O. niloticus body weight (b.w.) 0.65–812.3 g. Total capillary length and surface area and total morphometric oxygen diffusing capacity in body trunk red muscle had average values of 4792·7 (± 1740.7 s.e.) m, 415·4 (± 157·3 s.e.) cm² and 0·0213 (± 0·0075 s.e.) ml⁻¹ min⁻¹ cm⁻² mmHg respectively. When expressed as functions of b.w. these parameters had scaling values of 1·02, 1·07 and 0·993 respectively. These figures show a slight increase or almost no change in these structural parameters (which affect diffusion of oxygen to mitochondria in red muscle) per unit weight of fish. This should be important as the role of sustained swimming (by red muscle) becomes more important in larger tilapia. Oxygen diffusion distances were short [3·11 (±0·16 s.e.) μm] which facilitates diffusion of oxygen to mitochondria. The scaling value for oxygen diffusion distances of 0·067 (with respect to body weight) shows a slight increase in this parameter with development. This value is significantly different from zero.     

温度和个体大小对单齿螺耗氧率和排氨率的影响

采用静水法测定了不同温度、不同个体大小的单齿螺耗氧率和排氨率。结果表明:在16-33℃的实验温度范围内单齿螺的耗氧率(R_O)和排氨率(R_N)与软体部干重(W)都呈负相关,它们之间关系可以分别用幂函数R_O=aW^-b和R_N=a₁W^-b1表示。16～29℃温度范围内单齿螺的耗氧率和排氨率均随温度的升高而增加,29℃时耗氧率和排氨率达到最大值,当温度继续升高超过29℃后,耗氧率和排氨率则随温度的升高而下降,耗氧率、排氨率与温度之间呈显著的指数函数关系R_O=ce^dT和R_N=c₁e^d1T;不同个体大小单齿螺的O:N比在16～20℃时较大,Q₁₀取值范围0.56-3.74,平均值为1.64。方差分析表明,温度、软体部干重对单齿螺的耗氧率和排氨率均有极显著的影响(P<0.01)。     

红宝石球花报春腋芽再生体系的建立

以红宝石球花报春(Primula denticulata)无菌苗腋芽为外植体, 通过对丛生芽诱导、增殖、生根、炼苗和移栽等技术进行研究, 筛选出各阶段的最佳培养基配方, 建立了红宝石球花报春的再生体系。结果表明, 适宜红宝石球花报春腋芽诱导不定芽的培养基为MS+1 mg·L^-1 NAA+0.1 mg·L^-1 6-BA, 诱导率达73.33%; 适宜丛生芽增殖的培养基为MS+1 mg·L^-1 NAA+0.5 mg·L^-1 6-BA, 增殖率达85.19%; 最佳生根培养基为1/2MS+0.2 mg·L^-1 NAA, 生根率达95.59%; 最佳移栽基质为草炭:珍珠岩=3:1 (v/v)的混合基质, 移栽成活率可达96.67%。