莫桑鼻给非鲫滤泡闭锁中液晶形成的冰冻蚀刻研究

本文运用电镜的冰冻蚀刻术研究了莫桑鼻给非鲫滤泡闭锁中液晶形成的过程.结果表明,卵巢内的颗粒细胞吞噬大量的卵黄物质,消化后形成同心圆片层体,这是一种类脂加水以及镶嵌少量的蛋白质的溶致液晶态;细胞内的酶类参与液晶的形成;同时讨论了生物体内相变及液晶态存在的意义.     

莫桑鼻给非鲫滤泡闭锁中液晶形成的光镜和电镜观察

许多研究结果表明生物体內普遍存在流动而有序的液晶态结构,液晶态和生命活动的关系已受到人们的高度重视。在研究莫桑鼻给非鲫的卵子发生时发现,卵巢内存在大量的滤泡闭锁现象。同时发现这种现象伴随着液晶态的出现。滤泡闭锁和液晶形成的关系如何?液晶形成的意义何在?为此,运用光镜和电镜观察了滤泡闭锁的过程。     

小黄鱼内耳淋巴液液晶与耳石结晶关系的初步研究

作者以扫描电镜观察了小黄鱼耳尘的“透镜样”结构;Ｘ衍射分析表明小黄鱼耳石由ＣａＣＯ３霰石构成;以偏光显著镜发现内耳淋巴液中有液晶态存在。最后,以液晶理论对耳尘、耳石的形成进行了讨论。     

生物胆汁液晶态的研究

本文报导了用偏光显微镜、电子显微镜研究人体胆汁中的液晶态.结果表明:胆汁中存在有双射折的微粒,它们的图象指出是具有片层结构的液晶态.胆汁中还存在有类脂球滴液晶.     

鸡胚肝脏液晶类脂滴冰冻蚀刻结构研究

鸡胚肝脏组织中液晶类脂滴在不同温度及不同降温速度等条件下,呈现出液晶、结晶及各向同性态,并且三相之间可以互相转变.以冰冻蚀刻复型的方法,证实鸡胚发育中肝脏类滴液晶态为迟晶型液晶,并对0℃处理后的类脂满结晶进行了观察.最后对鸡胚肝脏液晶类脂滴与低密度脂蛋白的相似性进行了讨论.     

苯及丙酮对磷脂酰乙醇胺液晶态结构的影响

用小角 X 射线散射(SAXS)法研究了苯、丙酮对磷脂酰乙醇胺(PE)液晶态结构的影响.实验结果表明:苯能使 PE 液晶态先从片层相解束变成立方相.然后再诱导立方相变成六角形 H_Ⅱ相,最后促使六角形 H_Ⅱ相解束变成液态.在解束相变中出现了红移现象.丙酮也有使 PE 液晶态先从片层相解束变成立方相,在解束相变中也出现红移现象,但再诱导立方相变成六角形 H_Ⅱ相之后,不是促使其变成液相,而是将其稳定在六角形 H_Ⅱ相.     

鸡胚发育中肝脏类脂滴液晶态结构的研究

本文应用小角x射线衍射法,辅之以差热分析(DTA)和偏光显微镜法,研究了鸡胚肝脏中的液晶态类脂滴的结构和相变特性.结果表明:肝脏类脂滴是由同心的片层构成的球形颗粒,片层厚度为37(?);在室温及不高于其生理温度的范围内,处于片层状液晶态,在37～41℃,则转变成各向同性液态.并认为此片层状液晶态可能具有特殊的生物功能.     

鸡胚发育中肝脏类脂滴液晶态及体外结晶态的相变特性研究

观察到鸡胚发育中肝脏液晶类脂滴在降低温度时,可向结晶态转变,类脂滴液晶——结晶——各向同性态三相之间可互相转变。肝脏组织中液晶类脂滴在0℃左右转变为结晶;结晶在39—43℃时转变成各向同性类脂滴(正交偏光下无双折射);后者在热的铜样品台上,随样品台缓慢自然降温至35—36℃时又转变成结晶态;各向同性类脂滴在较快速度降温时,则转变成液晶态类脂滴。     

液晶态生物膜结构及其相变同功能的关系

液晶态物质广泛存在于自然界。据统计约每200种有机化合物中就有一种是液晶分子。生命系统中液晶态结构也普遍存在。液晶态为我们从物理角度理解和阐明生物大分子、细胞结构与功能的关系提供了一个有用的概念。目前低分子液晶的基本结构及特性已较清楚,但对生物大分子的液晶     

《液晶和生物结构》

最初发现的液晶都是些单一化合物,如胆甾醇苯酸酯。它有两个明确的熔点,在每个熔点前后各具不同的特征。在液态时,分子排列是无规的。当温度低于较高熔点时,根据分子的不同排列结构,呈线型或皂型液晶态。形成线型液晶态的分子,其长宽比为5:2,彼此平行排列,在三维空间中自由移动,而且是围绕着     

THE ROUTE OF ENTRY AND LOCALIZATION OF BLOOD PROTEINS IN THE OOCYTES OF SATURNIID MOTHS

The oocytes of saturniid moths take up proteins selectively from the blood. The distribution of blood proteins in the ovary during protein uptake was investigated by staining 2 µ sections of freeze-dried ovaries with fluorescein-labeled antibodies. The results indicate that blood proteins occur primarily in the intercellular spaces of the follicle cell layer, in association with a brush border at the surface of the oocyte, and within the oocyte in the yolk spheres. That proteins derived from the blood are associated with the yolk spheres was confirmed by isolating these bodies and showing that lysis, which can be induced by any of a number of mechanical means, causes them to release immunologically defined proteins known to be derived from the blood. That the level of blood proteins in the cytoplasm is low relatively to that in the yolk spheres was confirmed by the observation that the yellow pigments associated with several blood proteins, although conspicuous in the yolk spheres, are not visible in the translucent layer of centrifuged oocytes. From these and previous physiological observations, it is proposed that blood proteins reach the surface of the oocyte by an intercellular route, that they combine with some component of the brush border, and that they are transformed into yolk spheres by a process akin to pinocytosis.     

莫桑鼻给非鲫滤泡闭锁中卵黄溶致液晶的形变特征

运用透射电镜的超薄切片技术和冰冻蚀刻复型膜技术研究了莫桑鼻给非鲫滤泡闭锁过程中印黄溶致液晶YLLC的形态变化特征.结果表明、由颗粒细胞吞噬消化卵黄球所形成的YLLC通常是膜片层排列紧密的脂质体样结构,或为膜片层叠加排列的结构以及不规则的同心圆结构.这些YLLC结构不稳定,当被颗粒细胞释放后.因空间的扩大和水份的增加.YLLC吸水膨胀.形成规则的.膜间距增加的稳定脂质体样结构;YLLC能随体液流动,呈流体状.根据YLLC形态变化的行为,作者认为鱼类滤泡闭锁的生物学意义在于清除卵黄中不正常卵母细胞,并且使印黄物质重新吸收利用.但不参与内分泌激素的合成.     

莫桑鼻给非鲫卵黄球结晶体的电镜观察

运用透射电镜观察了莫桑鼻给非鲫卵母细胞内卵黄球的结构;卵黄球由被膜、结晶体及两者之间的非结晶区三部分组成。卵黄球结晶体呈斜方点阵,组成结晶体的卵黄高磷蛋白分子排列呈拟六角形列阵。本文还探讨了卵黄球结晶体形成的可能机制及生物学意义。     

Ultrastructural observations of previtellogenic ovarian follicles of dove

Dove ovarian follicle is a complex structure composed of oocyte surrounded by a somatic compartment consisting of theca externa, theca interna and granulosa. The structure of ovarian follicle (1 and 2 mm) of dove was studied by electron microscopy. The granulosa was pseudostratified in the 1-mm-diameter follicles and stratified with two or three irregular rows of cells in the 2-mm-diameter follicles. In the larger follicle indentations between oocyte and granulosa cells become more numerous and the microvilli of granulosa cell elongated to form a zona radiata with similarly elongated oocyte microvilli. Lining bodies were present at the tips of granulosa microvilli and in the cortical region of the oocyte. In the oocyte cortex were observed coated pits, coated vesicles, dense tubules, multivesicular bodies and primordial yolk spheres. Primordial yolk spheres may contain lining bodies and were observed fused with dense tubules and multivesicular bodies or associated with smooth cisternae.     

PROTEIN UPTAKE IN THE OOCYTES OF THE CECROPIA MOTH

The formation of yolk spheres in the oocyte of the cecropia moth, Hyalophora cecropia (L.), is known immunologically to result largely from uptake of a sex-limited blood protein. Recent electron microscope analyses of insect and other animal oocytes have demonstrated fine structural configurations consistent with uptake of proteins by pinocytosis. An electron microscope analysis of the cecropia ovary confirms the presence of similar structural modifications. With the exception of two apparently amorphous layers, the basement lamella on the outer surface of the follicular epithelium and the vitelline membrane on the inner, there is free access of blood to the oocyte surface between follicle cells. Dense material is found in the interfollicular cell space and adsorbed to the outer surface of the much folded oocyte membrane. Pits in the oocyte membrane and vesicles immediately under it are lined with the same dense material not unlike the yolk spheres in appearance. Introduction of ferritin into the blood of a developing cecropia moth and its localization adsorbed to the surface of the oocyte, and within the vesicles and yolk spheres of the oocyte cortex, is experimental evidence that the structural modifications of the oocyte cortex represent stages in the pinocytosis of blood proteins which arrive at the oocyte surface largely by an intercellular route. Small tubules attached to the yolk spheres are provisionally interpreted as a manifestation of oocyte-synthesized protein being contributed to the yolk spheres.     

Two-step consumption of yolk granules during the development of quail embryos

The mechanism of yolk consumption was studied morphologically and biochemically in Japanese quail Coturnix japonica. The amount of yolk granules in the yolk (or 'yolk cell') decreased in two steps during embryonic development. In the first step, during days 0-4 of incubation, the yolk-granule weight decreased at a rate of 13 mg/day. This decrease was due to segregation by endodermal cells that were newly formed in the developing yolk sac. In the second step after day 6, the decrease was drastic at a rate of 29.8 mg/day during days 6-12 and very slow thereafter. The decrease at the second step was due to the enzymatic digestion of yolk granules by cathepsin D that coexisted in yolk spheres. This digesting reaction was triggered by the solubilization of the granules with high concentrations of salts that were supplied after disruption of the limiting membrane of yolk spheres. The 'yolk cell' seemed to die around day 5 of incubation. Thus the digestion products might be taken up together with yolk lipids by endocytosis into the endodermal cells and transported to blood vessels.     

Cytochemical studies of developmental stages during oogenesis in Culex pipiens molestus (Forsk?l). I. Lipids and carbohydrates

Lipids and carbohydrates were studied in the polytrophic ovaries of Culex pipiens molestus during oogenesis. The cytoplasm of both the oocyte and the nurse cells contains lipid structures at all stages of development--granules in the early stages and spheres in the later stages. Intranuclear lipid bodies can be demonstrated in the oocyte and in the nurse cells. After leaving the nucleus, lipids are deposited in the peripheral cytoplasm. From the third to the seventh adult phase, lipid granules are concentrated in the area of the nurse cell and oocyte junction, indicating that lipids originate in the nurse cells and are transported from these to the oocyte. The follicular epithelial cells provide the oocyte with lipid material for fatty yolk synthesis and formation of the egg envelopes. Lipids are distributed similarly to the Golgi apparatus, indicating that there is a relationship between this organelle and fat formation. In the early stages, the cytoplasm of the oocyte, the nurse cells and the follicular epithelium contains glycogen granules. In the later stages these cells also contain mucopolysaccharides. The mucopolysaccharide yolk spheres are enclosed in vacuoles, while the chorion is composed of acid mucopolysaccharides. The follicular epithelium and vitelline membrane are of a mucopolysaccharide nature. A topographical relationship exists between the Golgi apparatus and the glycogen granules, indicating that this organelle also plays a role in glycogen synthesis.     

OVARIAN NUTRITIONAL RESOURCES DURING THE REPRODUCTIVE CYCLE OF THE HEMATOPHAGOUS DIPETALOGASTER MAXIMA (HEMIPTERA: REDUVIIDAE): FOCUS ON LIPID METABOLISM

In this study, we have analyzed the changes of the ovarian nutritional resources in Dipetalogaster maxima at representative days of the reproductive cycle: previtellogenesis, vitellogenesis, as well as fasting‐induced early and late atresia. As expected, the amounts of ovarian lipids, proteins, and glycogen increased significantly from previtellogenesis to vitellogenesis and then, diminished during atresia. However, lipids and protein stores found at the atretic stages were higher in comparison to those registered at previtellogenesis. Specific lipid staining of ovarian tissue sections evidenced remarkable changes in the shape, size, and distribution of lipid droplets throughout the reproductive cycle. The role of lipophorin (Lp) as a yolk protein precursor was analyzed by co‐injecting Lp‐OG (where OG is Oregon Green) and Lp‐DiI (where DiI is 1,10‐dioctadecyl‐3,3,30,30‐tetramethylindocarbocyanine) to follow the entire particle, demonstrating that both probes colocalized mainly in the yolk bodies of vitellogenic oocytes. Immunofluorescence assays also showed that Lp was associated to yolk bodies, supporting its endocytic pathway during vitellogenesis. The involvement of Lp in lipid delivery to oocytes was investigated in vivo by co‐injecting fluorescent probes to follow the fate of the entire particle (Lp‐DiI) and its lipid cargo (Lp‐Bodipy‐FA). Lp‐DiI was readily incorporated by vitellogenic oocytes and no lipoprotein uptake was observed in terminal follicles of ovaries at atretic stages. Bodipy‐FA was promptly transferred to vitellogenic oocytes and, to a much lesser extent, to previtellogenic follicles and to oocytes of ovarian tissue at atretic stages. Colocalization of Lp‐DiI and Lp‐Bodipy‐FA inside yolk bodies indicated the relevance of Lp in the buildup of lipid and protein oocyte stores during vitellogenesis.