不同育性三倍体长牡蛎性腺发育过程中的营养成分比较

为阐明不同育性三倍体长牡蛎性腺发育与营养成分变化的关系,实验对不育型和可育型三倍体长牡蛎性腺发育过程中的主要营养成分(糖原、总蛋白质和总脂肪含量)进行分析,并与二倍体长牡蛎进行比较。结果显示,三倍体长牡蛎性腺—内脏团、闭壳肌和外套膜3种组织中的糖原含量均显著高于同时期的二倍体长牡蛎,性腺—内脏团和闭壳肌中的总蛋白质含量则显著低于同时期的二倍体。随着性腺发育,可育型三倍体长牡蛎性腺—内脏团的糖原含量下降了31.88%,二倍体长牡蛎下降82.41%,而不可育型三倍体长牡蛎糖原含量下降了0.55%,这与糖原为配子发生供能密切相关。此外,不育型三倍体长牡蛎性腺—内脏团的糖原、总蛋白质和总脂肪含量在繁殖季节中均没有发现明显的波动,而可育型三倍体长牡蛎由于性腺一定程度的发育,其营养成分含量的变化趋势与二倍体类似。研究表明不育型和可育型三倍体长牡蛎在繁殖季节营养成分存在明显的差异,不育型三倍体的糖原品质性状优于可育型,这为长牡蛎育性控制育种提供了重要参考依据。     

二倍体和三倍体皱纹盘鲍精子发生过程的超微结构

比较了二倍体和三倍体皱纹盘鲍精子发生过程中细胞和细胞器的超微结构变化。结果表明,二倍体皱纹盘鲍的精子发生经历了精原细胞、初级精母细胞、次级精母细胞、精子细胞和精子5个阶段。其形态结构发生了一系列变化,主要包括：核染色质浓缩、线粒体的发达与融合、顶体形成和胞质的减少。三倍体皱纹盘鲍各种生精细胞的直径和核径均大于二倍体,精原细胞结构与二倍体相似;初级、次级精母细胞的胞质中,除溶酶体外,线粒体、内质网等细胞器少于二倍体,线粒体大小与二倍体没有差别,但形态不典型,层状嵴不发达;三倍体皱纹盘鲍的精子发生停滞在精子细胞阶段,表现出各种畸形状态,很多趋于解体,没有发现成熟精子。     

不同育性长牡蛎性腺发育过程中糖原和脂质的组织化学研究

为探讨不同育性长牡蛎(Crassostrea gigas)性腺发育过程中主要供能物质的利用和变化差异,利用过碘酸雪夫氏染色(PAS染色)和油红O染色法对不同育性三倍体长牡蛎及二倍体长牡蛎性腺组织进行观察分析。结果显示,增殖期,二倍体和三倍体长牡蛎性腺结缔组织中均含有大量糖原和脂质。随着性腺发育,二倍体和可育型三倍体(3nα型)长牡蛎性腺结缔组织中糖原含量明显下降,到成熟期几乎检测不到糖原,说明性腺结缔组织中的糖原为配子发生提供能量。脂质主要存在于性腺结缔组织和卵母细胞的细胞质中,说明脂质是卵细胞发育的重要组成物质。雌性二倍体和3nα型长牡蛎性腺结缔组织中的脂类含量随着性腺发育并未发生明显下降,推测糖原可能转化为脂质以满足性腺发育的物质需求。脂质在二倍体雄性长牡蛎的性腺发育过程中出现明显的减少,说明脂类在雄性性腺发育中的主要功能可能是供能而不是结构组成。糖原和脂类作为长牡蛎性腺发育过程中重要的供能和组成物质,在不育型三倍体(3nβ型)长牡蛎性腺发育过程中含量没有发生明显的变化,这与3nβ型配子发生受阻密切相关。推测3nβ型长牡蛎由于配子发育受阻,性腺发育初期积累的糖原和脂质并未分配至生殖细胞,而留在结缔组织中,从而使其在繁殖季节仍然能够保持快速生长。研究结果为牡蛎生殖发育调控机制及育性控制育种提供重要信息。     

团头鲂同源四倍体、倍间三倍体与二倍体红细胞的形态特征比较

通过比较同源四倍体、倍间三倍体与二倍体团头鲂（Megalobrama amblycephala）的红细胞、红细胞核的形态大小差异,探讨不同倍性团头鲂的红细胞形态遗传特征。结果表明：（1）团头鲂多倍体（同源4n和倍间3n）的红细胞数量显著低于二倍体（2n）团头鲂（P〈0．05）。其中,倍间三倍体团头鲂每毫升血液的红细胞数为二倍体的78．95％,而同源四倍体的红细胞数量下降幅度较大,仅为2n团头鲂的56．87％。（2）团头鲂同源四倍体、倍间三倍体的红细胞短径和长径、核短径和长径、红细胞表面积、红细胞体积和核体积均依倍性增加而显著增大（P〈0．05）;其中,又以核体积增大最为显著,同源四倍体、倍间三倍体的核体积分别为2n团头鲂的1．97倍和1．39倍。（3）团头鲂同源四倍体每毫升血液红细胞的总体积和总表面积,均明显低于二倍体和倍间三倍体团头鲂（P〈0．05）;倍间三倍体每毫升血液红细胞的总体积要多于二倍体团头鲂（P〈0．05）,但红细胞的总表面积在倍间三倍体与二倍体团头鲂间不存在显著差异（P〉0．05）。（4）在团头鲂同源四倍体中还观察到一定比例的异常红细胞现象。     

长牡蛎中国群体和美国群体杂交效应与三倍体的优势

将长牡蛎中国群体二倍体分别与美国群体二倍体和四倍体进行杂交,实验共设置4组,分别为杂交二倍体组、杂交三倍体组、中国二倍体组和美国二倍体组,比较了各实验组卵裂率、D幼率、D形幼虫大小及幼虫期、稚贝期的壳高生长、存活率等生物学指标,并估算杂交二倍体的杂种优势率和杂交三倍体的三倍体优势率。结果表明,杂交二倍体幼虫壳高生长的杂种优势率不明显,平均杂种优势率为1.21%,幼虫的存活率及稚贝的壳高生长表现出明显的杂种优势,平均杂种优势率分别为34.47%和20.39%。杂交三倍体的D形幼虫大小、幼虫和稚贝的壳高生长、存活率均表现出三倍体优势,D形幼虫大小三倍体优势率为5.19%,幼虫期壳高生长和存活的平均三倍体优势率分别为4.00%和19.92%,稚贝壳高生长和存活的平均三倍体优势率分别为30.18%和54.43%,200日龄,杂交三倍体鲜体质量的三倍体优势率为202.96%,存活三倍体优势率为73.60%。此外,稚贝期的杂交二倍体生长性状的杂种优势率和杂交三倍体的三倍体优势率均高于幼虫期的优势率。研究表明,中、美两地理群体杂交获得的三倍体长牡蛎子代生长和存活性状都比二倍体优良。杂交三倍体的优良性状主要是三倍体优势,杂交优势的贡献率还有待进一步实验证实。     

二、三倍体虹鳟肌肉组织结构及营养成分的比较

选取相同养殖条件下3个不同体质量组的二倍体虹鳟和三倍体虹鳟,其中每组二倍体和三倍体虹鳟各10尾,分析其肌肉常规营养成分、氨基酸含量和肌纤维密度及直径,以比较二倍体和三倍体虹鳟的肌肉品质特性差异。试验结果表明,随着体质量的增加,二倍体、三倍体虹鳟肌纤维密度均降低,而肌纤维直径增大;二倍体虹鳟肌纤维直径小于三倍体,密度大于三倍体(P0.05)。随着体质量的增加,二倍体和三倍体虹鳟肌肉水分含量和粗灰分含量减少,而粗蛋白、粗脂肪含量显著增加;三倍体虹鳟粗蛋白和粗脂肪含量显著高于同组二倍体(P0.05),水分和粗灰分含量略低于二倍体,均差异不显著(P0.05)。二倍体和三倍体虹鳟肌肉中谷氨酸含量均最高,三倍体虹鳟总氨基酸含量、必需氨基酸含量以及鲜味氨基酸含量高于二倍体;根据营养价值评价结果,二倍体和三倍体虹鳟均为蛋氨酸和胱氨酸总量最高,第一限制性氨基酸均为苯丙氨酸。整体上来说,二倍体虹鳟和三倍体虹鳟均为优质蛋白源,二倍体虹鳟嫩度优于三倍体,但随着体质量的增加,三倍体虹鳟肌肉在营养成分上较均衡,且鲜美度要优于二倍体,有更好的食用价值及营养价值。     

名品汇

［三倍体鲤鱼］◎出品：个旧市大屯镇靖辉鱼苗场,◎特点：由雌性鲤鱼和雄性草金鱼杂交而来,自身完全不育,生长速度比普通鲤鱼快30～50％。［三倍体牡蛎］◎出品：青岛崂东海珍品良种培育有限公司,青岛亚特兰生物科技股份有限公司。◎特点：用四倍体牡蛎和二倍体牡蛎杂交而来,不育,生长比二倍体快,个头比两倍体大30％。［绿康虾片］◎出品：汕头市宁杰水产饲料有限公司◎特点：对虾苗期饲料,悬浮性能和嗜口性好,营养全面。     

三倍体长牡蛎(Crassostrea gigas)不育性研究

三倍体长牡蛎(Crassostrea gigas)雌性怀卵量在0～2000万,雄性精量在0～1亿,大大低于正常二倍体。三倍体生殖腺发育受阻,大部分停留在增殖期和休止期,一部分虽发育至生长期和成熟期,但与同期的二倍体比较,生殖腺发育差。部分三倍体配子能完成受精作用,并发育至D形幼虫,但不能继续正常发育。卵子减数分裂后为含14～16条染色体的非整倍体。因此,三倍体长牡蛎是不育的。     

长牡蛎诱导三倍体与二倍体的养殖生物学比较研究

许多水产动物的三倍体在养殖生产中显示出很大的增产潜力 ,因此 ,采用染色体操作技术诱导三倍体的研究越来越受到人们的重视。长牡蛎( Crassostrea gigas)是我国沿海重要的经济贝类 ,长期以来 ,由于牡蛎繁殖季节大量排放精、卵 ,一是引起蛎肉瘪小充水 (成为透明状水蛎 ) ,致使肉质变劣而无法上市。二是雌性牡蛎大量排卵导致生理活性降低 ,出现大批死亡。近年来 ,笔者对长牡蛎三倍体的诱导和培育技术进行了深入、系统的研究 ,在三倍体生长发育、生殖腺组织学和超微结构变化、三倍体软体组织生化成分含量周年季节变化以及二倍体和三倍体的鉴…     

僧帽牡蛎三倍体和二倍体的生长比较↑（*）

１９９３ 年采用高温（３７ ℃） 休克处理受精卵１５ ｍｉｎ ,抑制第一极体排放诱导出僧帽牡蛎三倍体,在早期幼虫阶段,处理组幼虫平均壳长显著较对照组大,经过１ 年的养殖,三倍体壳长、壳高、软体部湿重和干重分别比二倍体增加１３ ．２ ％ 、８ ．９ ％ 、１２４ ．６ ％ 和８７ ．１ ％ 。１９９７ 年采用０ ．５ ｍｇ／Ｌ 细胞松弛素Ｂ 在５０ ％ 受精卵出现第一极体时处理受精卵１５ ｍｉｎ 诱导出僧帽牡蛎三倍体,经过１４ 个月养殖,三倍体壳长、壳高、体重和软体部湿重分别比二倍体增加３９ ．２６ ％ 、１７ ．２５ ％ 、７２ ．５０ ％ 和１１８ ．４２ ％ ,除个别月份外,三倍体和二倍体的生长差异显著（ Ｐ＜ ０ ．０５） ,僧帽牡蛎三倍体较二倍体具有明显的生长优势。     

Standardization of photometric measurement of sperm concentration from diploid and tetraploid Pacific oysters, Crassostrea gigas (Thunberg)

To provide necessary standardization of procedures for cryopreservation of sperm, a spectrophotomeric method was developed to determine the sperm concentration of diploid and tetraploid Pacific oysters, Crassostrea gigas. Wavelengths of 380, 550, 581 and 780 nm were compared, and 550 and 581 nm were found to be the most sensitive and reliable. A linear relationship between sperm concentration and photometric absorbance was observed for sperm concentrations between 2 × 10⁷ and 2 × 10⁹ cells mL^?1. The regression equation for the standard curve at 550 nm for sperm of diploid oysters was Y=?8.528+1.165 log X. The equation for sperm of tetraploid oysters was Y=?8.844+1.236 log X. The equation at 581 nm for sperm of diploid oysters was Y=?8.07+1.104 log X. The equation at 581 nm for sperm of tetraploid oysters was Y=?8.331+1.167 log X. Comparisons derived from the standard curves at 581 nm between observed values and the predicted values indicated good agreement for sperm from diploid (coefficient of determination, r²=0.983) and tetraploid (r²=0.980) oysters.     

Studies on sperm of diploid and triploid tench, Tinca tinca (L.)

The tench Tinca tinca is an interesting fish from the viewpoint of polyploidy and related atypical reproduction aspects. Triploid tench were produced artificially. Studies of spermiation as well as of sperm motility and structure were performed on several triploid and diploid males simultaneously with individual experimental crosses with diploid females to define their reproductive capacities. The testes of triploids visually looked less developed in the most of cases with lower sperm production (0.05 cm³ sperm per male), GSI and weight of testes compared to diploids (0.58 cm³ sperm per male). Analysis of variance showed significant influence of ploidy level on the percentage of motile spermatozoa. Triploidy did not change percentage of live spermatozoa and velocity of spermatozoa at the first time of sperm movement. The study of sperm structure by scanning electron microscopy revealed that most sperm cells were of normal structure with some anomalies. Sperm heads of triploid and diploid males were mostly round-shaped, 1.86±0.2 and 1.6±0.18 μm in diameter. The midpiece of triploid spermatozoa was slightly narrower than that of diploid ones with typical cylindrical shape. Flow cytometry revealed sperm cells of triploids to be largely aneuploid (1.47 n) with high mosaic DNA, oscillating from haploid DNA content (1.0 n) to diploid DNA content (1.9 n). Experimental crosses between triploid males and diploid females revealed that these males were capable to stimulate effective development with relatively high level of fertilization and hatching rates from 0 to 70%. In conclusion, triploidization does not seem to guarantee sterility of tench.     

微卫星分离模式显示雄性三倍体鲫产生非整倍体精子

三倍体鲫(Carassius auratus)行天然雌核发育,其自然种群中却有较高比例的雄性个体,这些雄性个体的性腺发育正常,能产生有活力的精子。而且其精子的DNA含量约为体细胞的一半,显示三倍体鲫精子发生过程中可能经历了均等的减数分裂。流式细胞术虽然能够较准确地测定细胞群的平均DNA含量,但是却很难检测到单个精子中的个别染色体增减,要明确回答雄性三倍体鲫产生的精子是否为整倍体需要定量地检测单个精子的遗传组成。本研究用微卫星标记检测以雌性鲤(Cyprinus carpio)与雄性三倍体鲫为亲本构建的杂种家系的基因型,结果发现母本鲤的多态位点在子代中呈孟德尔分离,父本三倍体鲫具有三套鲫基因组,其等位基因在子代中呈随机分离。上述研究结果提示:三倍体鲫起源于二倍体鲫的同源加倍,而非二倍体鲫和鲤的种间杂交;三倍体鲫通过染色体的随机分离产生非整倍体的精子,其精子发生过程中没有均等的减数分裂。三倍体鲫行雌核发育生殖,却可能并非起源于种间杂交且群体中的雄性个体可育,因而是单性生殖鱼类中的一个特例。     

Cytogenetic mechanism for reversion of triploids to heteroploid mosaics in Crassostrea gigas (Thunberg) and Crassostrea ariakensis

Triploid oyster induction has been very successful. However, during field culture, a certain proportion of triploids apparently loses one set of chromosomes, ‘reverting’ to diploid–triploid mosaics. The revertants will lose their aquaculture advantages due to the recovery of reproductive ability. Mitotic chromosomes were observed in mosaics of Crassostrea gigas and Crassostrea Ariakensis to elucidate the cytogenetic mechanism of reversion. Most individuals showed a modal number of 30 in triploid cells and varying numbers of chromosomes in other cells. From all 15 mosaics of C. gigas and 16 mosaics of C. ariakensis individuals, high proportions of aneuploid cells with various numbers of chromosomes were observed. Most of the aneuploid cells were hypotriploid cells with 26–29 chromosomes. Notably, in 10 out of 15 C. gigas and 9 out of 16 C. ariakensis, some cells consisted of 20–26 well‐spread chromosomes and 3–10 chromosome ‘clumps’. Individuals with more chromosome clumps tended to have higher percentages of hypotriploid cells. The correlation between these two categories of cells was significant (P<0.05) in C. gigas and highly significant (P<0.01) in C. ariakensis. Thus, we conclude that some chromosomes are eliminated during mitotic divisions because they clump together and are thus unable to undergo normal segregation.     

虾夷扇贝精子形态结构和超低温冷冻损伤的电镜观察

应用透射电镜和扫描电镜技术,研究了超低温冷冻保存前后虾夷扇贝精子超微结构和形态的变化。结果显示,虾夷扇贝精子由头部、中段和尾部3部分组成,外被光滑质膜;顶体位于头部最前端,呈倒"v"形,细胞核近似圆柱状,电子密度较高;4个线粒体和两个相互垂直的中心粒构成了精子的中段;鞭毛细长,轴丝为典型的"9 2"结构。经超低温冷冻保存后,冷冻损伤的精子表现为:精子被膜肿胀、被膜与核膜分离、丢失;顶体破裂、内容物流出;线粒体解体、线粒体嵴变形;鞭毛被膜肿胀、部分精子鞭毛脱落。可以推测,超低温冷冻保存对精子膜、顶体、线粒体和鞭毛的损伤可导致冻精活力和受精能力的下降。     

Studies on the ultrastructure of spermiogenesis and spermatozoon of tongue fish,Cynoglossus semilaevis günther

Ultrastructures of spermiogenesis and spermatozoon of commercially valuable tongue fish Cynoglossus semilaevis Günther were investigated by means of transmission electron microscopy. The study shows that the spermiogenesis of C. semilaevis can be divided into four stages, and the course of spermatid differentiation included flagellum development, chromatin compaction, nuclear fossa formation, migration of diplosome and mitochondria with structural change and disappearance of residual cytoplasm. No acrosome was observed in spermatozoon of C. semilaevis. The nucleus of sperm was U‐shaped; the nuclear fossa was deep with a centriolar complex at the bottom composed by proximal centriole and basal body. Five to six mitochondria were located behind the nucleus in a circle, forming the midpiece of sperm. The sperm tail, 43±2.4 μm (n=5) long, had lateral fins and sacciform tissues in some parts of the tail, with axoneme shown of a typical ‘9+2’ pattern. The ultrastructural observation revealed that the sperm of C. semilaevis is of a primitive type among teleostean fish species.     

Induced triploidy in the bay scallop, Argopecten irradians, and its effects on growth and gametogenesis

Triploidy was induced in the bay scallop, Argopecten irradians, by treating newly fertilized eggs with cytochalasin B. Treatment for 20 min duration 10 min after fertilization resulted in 66% triploidy of scallops in the 0.05 mg/l cytochalasin treatment group and 94% triploidy of scallops in the 0.1 mg/l cytochalasin treatment group, detected by measuring the relative DNA content of scallop granulocytes using flow cytometry. Individually labelled scallops of known ploidy were grown in the Damariscotta River estuary in south-central Maine, U.S.A. from May 24 to September 15, 1982. Mean adductor muscle weight in triploid scallops was 73% greater than that of diploid controls and mean total body tissue wet weight was 36% greater. Shell inflation was significantly greater in triploids, while shell height and length were unaffected. The indexes of weight and glycogen content of the adductor muscle were significantly greater in triploids at the end of the growing season. The majority of triploid scallops failed to ripen during the summer months, while diploid scallops ripened and spawned.