Formation and early development of tetraspores of Polysiphonia urceolata （Rhodomelaceae, Rhodophyta）

Polysiphonia urceolata is one type of potential commercial red seaweeds used for breeding and cultivation, because of its significant biochemical and biomedical application. However, the information of breeding and seedling incubation for cultivation is limited, especially the early development. In this study, tetrasporohyte and gametophyte of P. urceolata were taken as the study materials in Huiquan Bay, Qingdao, China. The cleaned and sterilized tetrasporophytes and gametophytes were pre-cultured in sterilized seawater, then nurtured at 18°C, 25 μmol photons m⁻² s⁻¹ in 12:12 h (light:dark) photoperiod. Continuous observation under microscope showed that the early development consists of bipolar division stage and seedling stage. In the division stage, tetraspores germinate into bipolar sporelings that further differentiate into a colorless rhizoidal portion and a lightly pigmented upright shoot. The lightly pigmented rhizoidal cell develops to a rhizoid and the larger pigmented cell transforms to an erect axis. In the seedling stage, several quasi-protuberances appear on the erect axis and form juvenile seedlings. The results demonstrate the culture of P. urceolata from tetraspores under laboratory conditions. Supported by National Key Technology Support Program, Development Program of China (No.2006AA09Z21), National Natural Science Foundation of China (No. 40618001 and N_CUHK438/06) and Shandong Agricultural Seed Stock Breeding Project     

Early development of Chondrus ocellatus Holm （Gigartinaceae, Rhodophyta）

1 INTRODUCTION Red algae C. ocellatus lives in temperate zone of coastal area, and inhabits at substrates from high tide to low tide regions. Its life history is composed of three phases: tetrasporophyte, gametophyte and carposporophyte. Chondrus is one o…     

Effects of temperature and irradiance on early development of Chondrus ocellatus Holm (Gigartinaceae, Rhodophyta)

Chondrus is a type of commercially produced red seaweed that widely used for food and carrageen extraction. Although the natural life history of the alga had been well understood, the factors influencing development of the tetraspore and carpospore remain poorly understood. In the perspective of seedling resources, the regulation of early development is crucial for the seedling nursing; therefore, it is necessary to understand the physiological influences during its early development. In this study, we studied the effects of temperature and irradiance on the early development of Chondrus ocellatus Holm under laboratory conditions. The released tetraspores and carpospores were cultivated at different temperatures (10–28°C) and irradiances (10, 60 μmol photons m⁻²s⁻¹) with a photoperiod of 12L:12D. The results indicate that both tetraspores and carpospores are tolerant to temperatures of 10–25°C, and have the highest relative growth rate at 20°C. Irradiance variances influenced the growth of the discoid crusts, and the influence was more significant with increasing temperature; 60 μmol photons m⁻²s⁻¹ was more suitable than 10 μmol photons m⁻²s⁻¹. The optimum temperature and irradiance for the development of seedlings was 20°C and 60 μmol photons m⁻²s⁻¹, respectively.     

Early development of grateloupia turuturu (Halymeniaceae, Rhodophyta)

Grateloupia turuturu is a commercial red alga with potential value in nutraceuticals and pharmaceuticals. To supplement information on its life history and verify whether carpospores can be used for seedling culture, early development of G. turuturu was investigated under culture conditions (27°C, 10-13 mol/(m2.s) in irradiance, photoperiod 10:14 h L:D). Three physiological stages were recognized by continuous microscopic observation: division stage, discoid crust stage, and juvenile seedling stage. At the beginning of the division stage, the carpospores developed germ tubes into which the carpospore protoplasm was evacuated, and then the carpospore protoplasm in the germ tubes began to divide continuously until discoid crusts formed. Finally, upright thalli appeared on the discoid crusts and developed into juvenile seedlings. It took about 60 days for carpospores to develop into juvenile seedlings. The growth parameters, including germination rate for carpospores and discoid crust diameter, were recorded. These results contribute more information on the life cycle, and at the same time are of great significance in the scaling-up of artificial seedling cultures of G. turuturu.     

Variation of Bioaccumulation Ability of 2,2’,4,4’- Tetrabromodiphenyl Ether by Marine Diatom Skeletonema costatum Under Different N：P Ratios

The growth, biochemical content and bioaccumulation quantity of 2,2’,4,4’-tetrabromodiphenyl ether （BDE-47） in Skeletonema costatum were studied under different N：P ratios （1, 4, 16, 64 and 128）. All cellular biochemical contents of S. costatum presented decreasing trend over cultivation time. At early stage of cultivation, the cellular protein, carbohydrate and lipid in S. co-statum presented higher values in treatments of N：P=4 and 16. However, they were lower in these treatments at the late stage, but higher in treatments N：P=1 and 128. Similarly, BDE-47 levels per cell of S. costatum were higher in treatments of N：P=4 and 16 at early stage of cultivation, which were 3.8 and 3.7 ng （106 cells）-1, respectively. At the middle stage of cultivation, the BDE-47 level per S. costatum cell lowered;and it further reduced in the treatments of N：P=4 and 16 at the late stage with the values 0.6 and 0.5 ng （106 cells）-1, respectively. However, it rose in N：P=128, reaching up to 2.3 ng （106 cells）-1. Compared with BDE-47 per cell, BDE-47 per algal volume under different N：P ratios did not present obvious difference. The quantity BDE-47 accumulated per cell of S. co-statum was positively correlated with protein, carbohydrate and lipid per cell; meanwhile, the BDE-47 per volume had a positive correlation with biochemical content per volume. The variation of bioaccumulation ability of BDE-47 in S. costatum can be ex-plained by biochemical changes due to N：P ratios.     

Early stage differentiation of thallus cells ofPorphyra haitanensis (Rhodophyta)

The early stage differentiation of thallus cells ofPorphyra haitanensis T. J. Chang et B. F. Zheng was studied. Protoplasts or single cells were isolated from the blades using enzyme mixture comprising 2% sea snail gut enzyme and 1% cellulase. The isolated protoplasts or single cells were incubated in the MES medium. The cell differentiations were examined under the microscope at intervals after incubation. Four types of cell differentiation, namely, normal, abnormal, carposporangial and spermatorangial, and rhizoidal types, were observed. Since normal cell differentiations occur mostly in small thalli 50 mm in length and middle portions of big thalli 200 mm in length, it is essential to select tissues from these two kinds of thalli essential for commercial production.     

STUDY ON TISSUE CULTURE FOR GELIDIUM SEEDLING

As seedling culture is a crcial factor for successful cultivation of Gelidium, the authors researched tis-sue culture technology for producing seedlings. The merphogeny and experirmental ecology were observedand studied fully in 2-5 mm isoIated tissue fragments, appearaare of branching creepersand attaching structure and new erect seedlings production and development were studied. Fragments weresown on bamboo slice and vinyon rope. The seedlings were cultured 20-30 days indoor, then cultured inthe sea, where the density of erect seedlings was 3- 19 seedlings/cm~2, growth rate was 3.84%/day. The frondarising from seedlings directly was up to 10 cm per year. The ecological conditions for regenerated seedlingsare similar to the natural ones. The regenerated seedlings are sintable for raft culture in various sea areas.     

Study on tissue culture forGelidium seedling

As seedling culture is a crucial factor for successful cultivation ofGelidium, the authors researched tissue culture technology for producing seedlings. The morphogeny and experimental ecology were observed and studied fully in 2–5 mm isolated tissue fragments. Regeneration, appearance of branching creepers and attaching structure and new erect seedlings production and development were studied. Fragments were sown on bamboo slice and vinylon rope. The seedlings were cultured 20–30 days indoor, then cultured in the sea, where the density of erect seedlings was 3–19 seedlings/cm², growth rate was 3.84% day. The frond arising from seedlings directly was up to 10 cm per year. The ecological conditions for regenerated seedlings are similar to the natural ones. The regenerated seedlings are suitable for raft culture in various sea areas.     

Early development of Costaria costata (C. Agardh) Saunders and cultivation trials

Costaria costata (C. Agardh) Saunders is one of common kelps distributed in many coastal areas worldwide; however, in China, no reports have been made on cultivation of the genus. To investigate potential cultivation of the species in the northern part of China, trials on isolation and preservation of the gametophytes were conducted using C. costata from Korea; growth and development of the gametophytes were observed. We showed that at 10±1°C, 60 μmol m⁻²s⁻¹ and 12:12 h (L:D), freshly released zoospores settled down within 1 hour, and then developed into the primary cell during the following 2 days. After a vegetative growth phase lasting 6–8 days, female gametophytes became 3–4 times larger in diameter than that of the primary cell, but still remained at a unicellular stage, while male gametophytes divided into 4–10 cells with only a slight change in size. Fertilization occurred within 10 days after the zoospores were released from the sporangia, and the apical and basal tissues of the juvenile sporophyte divided and differentiated into the blade and stipe. Temperature and irradiance influenced gametophytic vegetative growth and developmental patterns. Generally, low irradiance (15 μmol m⁻²s⁻¹ and 30 μmol m⁻²s⁻¹) was unfavorable to the induction of fertility, but it enhanced female gametophyte division. The optimal conditions for vegetative growth were 15°C and 30 μmol m⁻²s⁻¹. After transplantation of the juvenile seedlings and after eight months cultivation, the harvested mature blade reached 194 cm in length and 32.7 cm in width. Our study proves that it is feasible to implement propagation and large scale cultivation of C. costata in northern China.     

以江蓠为栖息环境养殖的双齿围沙蚕性腺发育

研究以江蓠为养殖基质的双齿围沙蚕的配子发生及性腺发育。结果表明:1)根据双齿围沙蚕卵细胞形态特征、内部结构、卵径大小,卵母细胞的发生可划分为第Ⅰ时相(卵原细胞)、第Ⅱ时相(小生长期初级卵母细胞)、第Ⅲ时相(大生长期初级卵母细胞,卵黄形成前期、卵黄形成中期、卵黄形成后期)和第Ⅳ时相(成熟卵母细胞,胶膜形成前期、胶膜形成后期)等4时相;根据各时相卵子的数量变化及体腔中其他结构的形态变化,将雌性性腺分为Ⅰ期卵巢、Ⅱ卵巢、Ⅲ卵巢、Ⅳ卵巢和Ⅴ期卵巢等5个阶段。2)根据双齿围沙蚕体腔内精母细胞的大小、形态和所处的位置,将双齿围沙蚕的精子发生划分为精原细胞、初级精母细胞、次级精母细胞、精细胞和精子;根据各时相精子的形态和数量变化以及体腔中其他组织器官的形态变化,将双齿围沙蚕的雄性性腺划分为Ⅰ期精巢、Ⅱ期精巢、Ⅲ期精巢、Ⅳ期精巢和V期精巢等5个阶段。3)Ⅰ-Ⅳ期的性腺主要包含对应时相的生殖细胞,同时,也存在有少量其他时相的生殖细胞,生殖细胞的发育速度并不完全一致。     

Early development of Silvetia babingtonii (Fucales,Phaeophyceae)

Silvetia babingtonii is a potentially economic brown alga for sources of food and high-value added utilization. So far, sporeling nursery and field cultivation has not been successful. The lack of knowledge on development and life cycle of this alga hinder the development of techniques for the sporeings and cultivation. In this study, internal structure of oogonium and antherium of S. babingtonii was observed with hematoxylin and eosin staining and through microscope. Meanwhile, early development from zygotes to juvenile sporelings was studied at 20℃ under 60–100 μmol photons m-2 s-1. Zygotes germinated and divided into thallus and rhizoid cells. The larger thallus cells further divided and developed into juvenile sporelings; while the smaller rhizoid cells divided and elongated into rhizoid hairs. These findings documented the life cycle of S. babingtonii and provided fundamental knowledge for sporeling nursery in the near future.     

波纹龙虾胚胎的离体培养及发育观察

对波纹龙虾不同发育时期的胚胎进行离体培养和显微观察。结果表明,初始培育的离体胚胎愈接近孵化期,其孵化率愈高(最高达80.0%);波纹龙虾胚胎发育经历受精卵、卵裂期、囊胚期、原肠期、中眼色素形成期、复眼色素形成期、心跳期、破膜前期和出膜期;胚胎在发育过程中颜色变化:橙红→深橙红→砖红→灰白→接近透明。     

Optimization of conditions for tetraspore release and assessment of photosynthetic activities for different generation branches of Gracilaria lemaneiformis Bory

Gracilaria lemaneiformis Bory is an economically important alga that is primarily used for agar production. Although tetraspores are ideal seeds for the cultivation of G. lemaneiformis, the most popular culture method is currently based on vegetative fragments, which is labor-intensive and time-consuming. In this study, we optimized the conditions for tetraspore release and evaluated the photosynthetic activities of different colonies formed from the branches of G. lemaneiformis using a PAM (pulse-amplitude-modulated) measuring system. The results showed that variations in temperature and salinityhad significant effects on tetraspore yield. However, variations in the photon flux density (from 15 μmol m⁻² s⁻¹ to 480 μmol m⁻² s⁻¹) had no apparent effect on tetraspore yield. Moreover, the PAM-parameters Y(I), Y(II), ETR(I), ETR(II) and F _v/F _m of colonies formed from different branches showed the same trend: parameter values of first generation branches>second generation branches>third generation branches. These results suggest that the photosynthetic activities of different colonies of branches changed with the same trend. Furthermore, photosynthesis in G. lemaneiformis was found to be involved in vegetative reproduction and tetraspore formation. Finally, the first generation branches grew slowly, but accumulated organic compounds to form large numbers of tetraspores. Taken together, these results showed that the first generation branches are ideal materials for the release of tetraspores.     

甘蔗苗期耐盐性评价指标的研究

测定了8个不同耐盐性的甘蔗品种在正常和盐胁迫下的一些形态、生理指标的损伤率,并用因子分析进行了分析。分析表明,甘蔗苗期的耐盐性指标可以划分为反映甘蔗受盐害时物质形态伤害程度的植株形态指标和反映植株受害时生理和物质代谢活动变化的生理指标两大类型,其中植株形态指标是评价甘蔗苗期耐盐性的主要指标。并用这两类综合指标对参试品种苗期耐盐性大小进行了排序。     

培育密度、换水量和倒池培育对珠母贝浮游幼虫生长发育和存活的影响

以室内育苗池或玻璃缸养殖方式,研究了不同培育密度、换水量和倒池培育对珠母贝浮游幼虫生长发育和存活的影响。结果表明:当培育密度为0.8、1.2只/mL,直线铰合期时间分别为7.00、7.40d,日均生长为5.16、4.87μm,壳顶期时间分别为10.76d和10.77d,眼点期密度为0.58只·mL-1和0.60只·mL-1,差异不显著;日换水量分别为40%、60%、80%,直线铰合期时间、壳顶期时间、日均生长及眼点期密度差异不显著,日换水量40%能满足幼虫的生长和存活;壳顶初期进行倒池培育,能促进浮游幼虫的生长发育和提高其存活率。     

光及补料条件对室内管道光反应器中三角褐指藻生长和岩藻黄素积累的影响

【目的】制备富含岩藻黄素的三角褐指藻(Phaeodactylum tricornutum)生物质。【方法】采用470 L室内管道光生物反应器系统,研究自养培养下光源、调光策略、补料培养操作条件对于细胞生长、生物量浓度和岩藻黄素积累的影响。【结果】在采用LED灯、梯度提升照度及重复补料半连续培养模式下,三角褐指藻细胞密度、生物量和岩藻黄素产率最高分别可达3.16×10⁷mL^-1、1.64 g/L和1.90 mg/(L·d),分别是日光灯为光源条件下的2.77倍、3.09倍和2.38倍(P<0.01)。【结论】在管道光生物反应器中获得的自养培养条件,可强化三角褐指藻生物量和岩藻黄素积累,为三角褐指藻积累岩藻黄素的室内可控规模化技术开发提供指导。     

Advances in studies of the effects of starvation on growth and development of fish larvae

Starvation has important effects on early development of fish. It determines the survival and growth of fish larvae, and plays an important role in the dynamics of fish population and fisheries recruitment, in this review, we discuss the current studies about the effects of starvation on growth and development of fish larval stage. The goals of this review are to understand some adap- tive mechanisms and ecological countermeasures of starved fish larvae and to provide the scientific guideline for exploring early life history processes, evaluating the nutrition condition and growth of larval fish, protecting fish resource and breeding fish larvae.     

Improvement of the zygote utilization and reduction of the seedling loss in the early stage of seedling production of Sargassum thunbergii(Fucales,Phaeophyta)

Artificial seedling production of Sargassum thunbergii is an effective way to relieve pressure on natural resources.In order to improve the utilization of zygotes and reduce the loss of seedlings,studies on the characteristic of the zygotes release,the development of rhizoids,the attachment of germlings,and the influence of jet washing were conducted.Results show that the percent of zygotes released was increased with time in the first 60 h.The capacity of germlings attached to the substratum was significantly increased,especially coincident with the time of the new rhizoids emerged and elongated.The detachment rate of germlings significantly decreased with the delay of starting time of jet washing or the reduction of jet washing velocity.However,the jet washing at any level applied in the experiment could cause considerable loss of germlings within the 20 days after the attachment.Our study provided some parameters to optimize the operation in the early stage of seedling production.     

Improvement of the zygote utilization and reduction of the seedling loss in the early stage of seedling production of <Emphasis Type="Italic">Sargassum thunbergii</Emphasis> (Fucales,Phaeophyta)

Artificial seedling production of Sargassum thunbergii is an effective way to relieve pressure on natural resources. In order to improve the utilization of zygotes and reduce the loss of seedlings, studies on the characteristic of the zygotes release, the development of rhizoids, the attachment of germlings, and the influence of jet washing were conducted. Results show that the percent of zygotes released was increased with time in the first 60 h. The capacity of germlings attached to the substratum was significantly increased, especially coincident with the time of the new rhizoids emerged and elongated. The detachment rate of germlings significantly decreased with the delay of starting time of jet washing or the reduction of jet washing velocity. However, the jet washing at any level applied in the experiment could cause considerable loss of germlings within the 20 days after the attachment. Our study provided some parameters to optimize the operation in the early stage of seedling production.     

New phenomenon in early development of sporelings in Gracilaria asiatica Chang et Xia （Gracilariaceae, Rhodophyta）

1 INTRODUCTION The red alga Gracilaria belongs to Gracilari- aceae, Gigartinales, Florideophyceae, and includes over 100 recorded species, wildly distributing in tropical and temperate regions (Oliveira and Plastino, 1994), and is useful for producing val…