宁夏水产试验场死鱼原因和小三毛金藻在宁夏的分布

本文报道了笔者在宁夏水产试验场现场观察到的二龄鲢、鳙鱼种(体重50～150g)因小三毛金藻(Prymnesium parvum Carter)大量发生引起中毒死亡的情况。并通过采自宁夏几个主要地区的169个水样的观察分析，对小三毛金藻在该地区的分布情况做了简要说明。同时分析了小三毛金藻与盐度的关系，提出了盐度在4～8‰时，该种藻类有大量发生和形成优势种的趋势，建议该地区可以用水化学指标(盐度4～8‰)来指示该种害藻的发生。     

中国小三毛金藻研究述评

本文对小三毛金藻在我国的发现和研究工作做一总结。文中澄清了长期以来国内三毛金藻属分类上的混乱,肯定了各地引起鱼类大量死亡的金鞭藻均属同一种类,并对中国小三毛金藻的形态、分布,生态、病状、防治等方面的研究成果作了综述和评论。     

硫铵和福尔马林对小三毛金藻光合作用和生长的影响

小三毛金藻(prymncsium parvum carter)孳生于有一定盐度的半咸水水体中,所分泌的毒素常使鱼类中毒,严重时引起鱼类大量死亡。目前已有一些药物防治方法,如硫铵、硫酸铜、黄泥浆等。为了探索更有效的防治措施,本实验研究了硫铵和福尔马林对小三毛金藻光合作用和生长的影响。     

养鱼改碱,渔农结合的技术(五)

五、鱼病防治 除了淡水养鱼常见鱼病防治之外,在盐碱地新挖鱼塘养鱼出现的特殊情况,主要是与高盐碱度有关的鱼病,如三毛金藻毒素中毒病、鲤巨角鳋病和急性氨中毒症等。 (一)三毛金藻毒素中毒症 1.症状:中毒初期,病鱼游向鱼     

小三毛金藻的防治

水温>15℃,pH8.0以上时,在池塘遍撒5—17ppm的硫铵或0.7ppm的硫酸铜,可使因小三毛金藻轻微致毒的病鱼减缓病情或恢复正常,但难以控制小三毛金藻的数量;如果定期施用5ppm的硫铵或20—30公斤/亩·日的有机肥,便可有效地预防该害藻所引起的鱼病。 在不缺磷的池塘施用磷肥对防治小三毛金藻的发生毫无裨益。 陆地黄泥浆对小三毛金藻毒素有吸附作用,大剂量施用可缓解鱼病但不能抑制害藻的孳生。     

花鲈头肾的显微结构和超显微结构

应用光镜和电镜技术观察了花鲈头肾的显微与超显微结构.结果表明,花鲈头肾是一个重要的造血和免疫器官.头肾实质无肾单位,主要由淋巴组织和血窦构成,可分为淋巴细胞聚集区和粒细胞聚集区.电镜下观察显示,花鲈头肾主要由淋巴细胞、浆细胞、单核细胞、巨噬细胞和粒细胞组成,根据胞浆内特殊颗粒的形态结构和大小将粒细胞分为Ⅰ、Ⅱ、Ⅲ型粒细胞.     

冬季水产养殖须提防三毛金藻

<正>三毛金藻是一种广盐性藻类,其大量繁殖时,向水中分泌细胞毒素,进而使鱼类和水生动物中毒死亡。三毛金藻是盐碱地区水产养殖的一大毒藻,危害鲢、鳙、鳊、草鱼、梭鱼、鲤、鲫、鳗、鳅等多种鱼类及用鳃呼吸的水生动物,从夏花到亲鱼均可受害。三毛金藻四季都有发生,主要发生于春、秋、冬季,因这时的水温较低,其他藻类受低     

树莓果实显微及超显微结构观察

以树莓品种菲尔杜德(Rubus idaeus L.cv.Fertod Zamatos)为试材,分别采集花后7、14、21、28、30、32 d的果实,进行显微结构和超显微结构观察。结果表明,树莓果实由外、中、内3层果皮和种子组成,属于聚合小核果类型。在果实发育初期,细胞排列紧密,细胞壁明-暗-明结构明显,细胞器丰富。随着果实成熟变软,果肉细胞细胞壁发生扭曲变形,中胶层瓦解,明暗分区结构消失,细胞器显著减少,质壁分离严重。     

盐度碱度pH值和硫铵对小三毛金藻生长的影响

用f/2改良培养液Ⅰ分离出小三毛金藻大连品系。细胞大小为7～15.8微米×63—9.5微米(长×宽),长鞭毛8.4—13.7微米,附鞭2.1—3.7微米。藻体可以在盐度为0.45—32.25‰的培养液中存活,11.78—161‰时生长最好,30毫克当量/升以上的碱度对小三毛金藻有毒害作用。500—1000ppm的硫铵可使培养物细胞在5小时内全部解体。但是在温度为22.7℃,pH值7.94,硫铵浓度为5—25ppm的培养液中生长良好。     

6种野生鸢尾种皮、种苗特征与进化的关系

以鸢尾属中6种东北野生植物——玉蝉花(Iris ensata)、溪荪(I.sanguinea)、北陵鸢尾(I.typhifo-lia)、黄菖蒲(I.pseudacorus)、燕子花(I.laevigata)、马蔺(I.lacteal)为对象,对其种皮超显微结构、种苗结构进行了比较研究,探讨了两者与进化的关系。结果表明:鸢尾属种皮微形态特征的网脊龙骨状、网眼较浅的是较原始特征,表面有凹点或网脊较宽、网眼较深的是较进化的特征。初步推断,6种鸢尾的进化关系是溪荪→北陵→燕子花→黄菖蒲→玉蝉花→马蔺;种苗有舌状鞘的种类是较进化的类型。由此得出的进化关系与种皮电镜所得出的结论是一致的。     

Farmington meteorite: cristobalite xenoliths and blackening

The Farmington chondrite contains two small xenoliths of granular cristobalite, each surrounded by a thin reaction rim of diopsidic clinopyroxene. Similarities between the blackened structure and drusy cavities, characteristic of this meteorite, and those of an experimentally heat-treated chondrite suggest that Farmington was reheated rather than shocked, but neither the exact stage in the history of this stone at which reaction rims developed around the xenoliths nor the source of the calcium necessary to form rim diopside have been established with certainty.     

Argon-40: excess in submarine pillow basalts from kilauea volcano, hawaii

Submarine pillow basalts from Kilauea Volcano contain excess radiogenic argon-40 and give anomalously high potassium-argon ages. Glassy rims of pillows show a systematic increase in radiogenic argon-40 with depth, and a pillow from a depth of 2590 meters shows a decrease in radiogenic argon40 inward from the pillow rim. The data indicate that the amount of excess radiogenic argon-40 is a direct function of both hydrostatic pressure and rate of cooling, and that many submarine basalts are not suitable for potassium-argon dating.     

Graphite whiskers in CV3 meteorites

Graphite whiskers (GWs), an allotrope of carbon that has been proposed to occur in space, have been discovered in three CV-type carbonaceous chondrites via Raman imaging and electron microscopy. The GWs are associated with high-temperature calcium-aluminum inclusion (CAI) rims and interiors, with the rim of a dark inclusion, and within an inclusion inside an unusual chondrule that bears mineralogy and texture indicative of high-temperature processing. Current understanding of CAI formation places their condensation, and that of associated GWs, relatively close to the Sun and early in the condensation sequence of protoplanetary disk materials. If this is the case, then it is a possibility that GWs are expelled from any young solar system early in its history, thus populating interstellar space with diffuse GWs. Graphite whiskers have been postulated to play a role in the near-infrared (near-IR) dimming of type Ia supernovae, as well as in the thermalization of both the cosmic IR and microwave background and in galactic center dimming between 3 and 9 micrometers. Our observations, along with the further possibility that GWs could be manufactured during supernovae, suggest that GWs may have substantial effects in observational astronomy.     

Discovery of vapor deposits in the lunar regolith

Lunar soils contain micrometer-sized mineral grains surrounded by thin amorphous rims. Similar features have been produced by exposure of pristine grains to a simulated solar wind, leading to the widespread belief that the amorphous rims result from radiation damage. Electron microscopy studies show, however, that the amorphous rims are compositionally distinct from their hosts and consist largely of vapor-deposited material generated by micrometeorite impacts into the lunar regolith. Vapor deposits slow the lunar erosion rate by solar wind sputtering, influence the optical properties of the lunar regolith, and may account for the presence of sodium and potassium in the lunar atmosphere.     

Mariner 9 television reconnaissance of Mars and its satellites: preliminary results

At orbit insertion on 14 November 1971 the Martian surface was largely obscured by a dust haze with an extinction optical depth that ranged from near unity in the south polar region to probably greater than 2 over most of the planet. The only features clearly visible were the south polar cap, one dark, spot in Nix Olympica, and three dark spots in the Tharsis region. During the third week the atmosphere began to clear and surface visibility improved, but contrasts remained a fraction of their normal value. Each of the dark spots that apparently protrude through most of the dust-filled atmosphere has a crater or crater complex in its center. The craters are rimless and have featureless floors that, in the crater complexes, are at different levels. The largest crater within the southernmost spot is approximately 100 kilometers wide. The craters apparently were formed by subsidence and resemble terrestrial calderas. The south polar cap has a regular margin, suggsting very flat topography. Two craters outside the cap have frost on their floors; an apparent crater rim within the cap is frost free, indicating preferentia loss of frost from elevated ground. If this is so then the curvilinear streaks, which were frost covered in 1969 and are now clear of frost, may be low-relief ridges. Closeup pictures of Phobos and Deimos show that Phobos is about 25 +/-5 by 21 +/-1 kilometers and Deimos is about 13.5 +/- 2 by 12.0 +/-0.5 kilometers. Both have irregular shapes and are highly cratered, with some craters showing raised rims. The satellites are dark objects with geometric albedos of 0.05.     

Alpha-particle activity of apollo 11 samples

Nine polishled thin sectionis have been exposed to nulclear track plates, three have been counted by alplia-particle spectrometry, and one has been examined by electron mocroprobe. Interpretation of the results is in a preliminary stage. Alpha track distribiutioni in the autoradiograph of a breccia forms a network that appears related to the rims of accretionary lapilli comiiposinig the breccia. Thorium in a coarse-grained crystalline rock is concenitrated in micron-sized, zirconium-rich crystals. Alplia count rates agree with what would be predicted from previously reported thorium and uranium contents of the same rocks, suggesting secular equilibriunm for the thorium and uranium decay series.     

Ancient multiring basins on the moon revealed by clementine laser altimetry

Analysis of laser altimetry data from Clementine has confirmed and extended our knowledge of nearly obliterated multiring basins on the moon. These basins were formed during the early bombardment phase of lunar history, have been filled to varying degrees by mare lavas and regional ejecta blankets, and have been degraded by the superposition of large impact craters. The Mendel-Rydberg Basin, a degraded three-ring feature over 600 kilometers in diameter on the lunar western limb, is about 6 kilometers deep from rim to floor, only slightly less deep than the nearby younger and much better preserved Orientale Basin (8 kilometers deep). The South Pole-Aitken Basin, the oldest discernible impact feature on the moon, is revealed as a basin 2500 kilometers in diameter with an average depth of more than 13 kilometers, rim crest to floor. This feature is the largest, deepest impact crater yet discovered in the solar system. Several additional depressions seen in the data may represent previously unmapped ancient impact basins.     

The formation of chondrules: petrologic tests of the shock wave model

Chondrules are millimeter-sized rounded igneous rocks within chondritic meteorites. Their textures and fractionated mineral chemistries suggest that they formed by repeated, localized, brief (minutes to hours) melting of cold aggregates of mineral dust in the protoplanetary nebula. Astrophysical models of chondrule formation have been unable to explain the petrologically diverse nature of chondrites. However, a nebular shock wave model for chondrule formation agrees with many of the observed petrologic and geochemical properties of chondrules and shows how particles within the nebula are sorted by size and how rims around chondrules are formed. It also explains the volatile-rich nature of chondrule rims and the chondrite matrix.     

Vaccination with pcDNA3-15/60 Naked DNA Encoding the Surface Protein of Sporozoites in Cryptosporidium parvum

The CP15/60 gene encoding the CP15/60 surface protein of sporozoites in Cryptosporidium parvum was obtained by PCR so as to research the nucleic vaccine against C.parvum. The eukaryotic expressing vector pcDNA3-15/60 was constructed by inserting CP15/60 gene into pcDNA3 (+) in Xho Ⅰ and EcoR Ⅰ. A vaccination protocol was the adult pregnant goats inoculated intranasally with the pcDNA3-15/60 plasmid and their offspring were infected with C.parvum oocysts. The results showed that the pcDNA3-15/60 plasmid can induce the immune response of goats and the vaccinated goats can transfer the immunity to offspring conferring protection against C.parvum infection. These suggested that the recombinant plasmid could be a DNA vaccine candidate.