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Two new Ulvella species, U. elegans R. Nielsen & K. Gunnarsson and U. islandica R. Nielsen & K. Gunnarsson are described. These microfilamentous marine green algae were found in the sublittoral zone in northern Iceland, epiphytic on Euthora cristata and associated with a calcareous polychaete tube, respectively. Unialgal cultures were established from field-collected material for morphological observations. In culture, Ulvella elegans was characterized by rosettes of monostromatic pseudoparenchyma consisting of radiating filaments with a margin of mutually free filaments. Each cell had one pyrenoid. Hairs were not observed. Ulvella islandica had a heterotrichous morphology, consisting of dense tufts of upright broad branches and much narrower, rhizoid-like branches. Acrochaete-type hairs occurred; these are hyaline non-septate merocytic extensions from a more or less bulbous base, which may be separated from the vegetative cell below. Most cells had one pyrenoid except for a few broad cells which had two or three. In a phylogenetic reconstruction based on the chloroplast-encoded tufA gene, the sequences for the two species were clearly distinct from any other Ulvella sequence available for this gene. Ulvella islandica was placed in a clade together with U. lens, U. wittrockii, U. reticulata and U. pseudorepens. Ulvella elegans occupied a branch deep in the phylogeny but the position was poorly supported.  相似文献   

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Due to the total and unexpected collapse of the Iceland scallop, Chlamys islandica, stocks around Iceland during the 2000s, a commercial fishing ban has been imposed on this valuable resource since 2003. Following the initial identification of an apicomplexan parasite in the scallops, a long-term surveillance program was established to evaluate the effect of the parasite on the population. The infections were highly prevalent in all shell sizes throughout the study. However, the parasite only impacts mature scallops where they cause severe macroscopic changes, characterized by an extensively diminished and abnormally coloured adductor muscle. A highly significant relationship was observed between infection intensity and gonad and adductor muscle indices. The first four years of the study, were characterized by high infection intensity and very poor condition of the adductor muscle and gonads, whilst during subsequent years, infections gradually decreased and the condition of the scallops improved. Histopathological changes were restricted to the presence of apicomplexan zoites which were widely distributed, causing varying degrees of pathology in all organs. In heavy infections, muscular and connective tissues were totally necrotized, destroying significant parts of numerous organs, especially the adductor muscle, digestive gland and gonads. The progression of the disease was in good synchrony with the mortality rates and the subsequent decline observed in the scallop stock and recruitment indices. Our findings strongly suggest that the apicomplexan parasite played a major role in the collapse of the Iceland scallop stock in Breidafjordur. In addition to causing mortality, the infections significantly impact gonad development which contributes further to the collapse of the stock in the form of lower larval recruitment. Furthermore, compelling evidence exists that this apicomplexan pathogen is causing serious disease outbreaks in other scallop populations. Similar abnormal adductor muscles and the parasite itself have been identified or observed in association with other mass mortality events in several different scallop species and commercial stocks in the northern hemisphere.  相似文献   

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Indiscriminate use of synthetic pesticides to control the pests causes negative effects on non-target organisms. Some of the chemicals under B and C categories are carcinogenic to humans. The present study was aimed to assess the antifeedant, larvicidal and pupicidal activities of Hygrophila schulii (syn. H. auriculata) and Blumea mollis against Helicoverpa armigera. Maximum antifeedant activity of 70.01% was observed in ethyl acetate extract of H. schulii at 5.0% concentration with LC50 value of 2.0%. B. mollis ethyl acetate extract at 5.0% concentration showed antifeedant activity of 35.40% with LC50 value of 8.38%. The data for antifeedant activity showed homogeneity of variances in Levene Statistics and normality in Shapiro–Wilk test. Ethyl acetate extract of H. schulii at 5.0% concentration showed 68.66% larvicidal activity with LC50 value of 2.97%. It also showed 73.33% pupicidal activity and was statistically significant from other treatments. No pupicidal activity was observed in ethyl acetate extract of B. mollis. All concentrations of ethyl acetate extract of H. schulii showed promising biological activities which differed statistically from other treatments. Ethyl acetate extract of H. schulii could be used to develop new botanical formulations to manage agricultural pests.  相似文献   

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B.B.Brodie博土,一个先驱药理学家和美国国家科学院院士,1989年2月28日逝世。生前是美国国立卫生研究院心脏研究所化学药理实验室的创始人和第一任主任。  相似文献   

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《菌物学报》2002,21(4)
1902年12月12日出生于福建省福州市。 1915年考入北京清华学堂。 1923年赴美国康奈尔大学留学取得农学士、森林学硕士学位。 1925—1928年攻读康奈尔大学植物病理学博士并被授予全美国最高科学学会 PHI-KAPPA-PHI和SIGMA-XI两枚金钥匙证章并成为其荣誉会员。 1928年回国,任岭南大学、金陵大学和中央大学一级教授。 1932—1941年历任中国科学社生物研究所、中央自然历史博物馆、中华教育文化基金董事会和中央研究院动植物研究所研究员、中央研究院林业实验研究所副所长。 1941—1946年任甘肃省水利林牧公司林业部经理。 1948年当选…  相似文献   

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. .OOB epea MHe Ha opeeeHe Heobo MaTepa,copaHHbi BpobH HHaHb. e ocaHHbix.BOB TaM Mecb--Blastophagus piniperda L.,Hylurgopssuleatus Egg.,Pityophthorus lichtensteini Ratz.,Orthotomicus angulatus Eich=golovijankoiPjat.u lps nitidus Egg.poKo pacpocTpaHeHHbi oT CeBepHo Map o  相似文献   

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A clone ofScenedesmus quadricauda, isolated from Tjeukemeer, exhibits a high degree of morphological variation in synchronized cultures. Cells are synchronized by light-dark cycles. During the photoperiod they build up the capacity to divide. First division into 2- and 4-celled coenobia is induced, then during the second half of the photoperiod the induction of division into 8 unicells takes place. Division itself and the subsequent liberation of daughter cells occur in the dark period.By giving a definite photoperiod the formation of either coenobia or unicellular stages is determined. The formation of both coenobia and unicells is followed using a light microscope. In both cases only the pattern of cytokinesis is similar. After cytokinesis the unicells become ovoid in shape and form two spines at each pole. They are released from the parental wall as separate cells and show remarkable similarity to theChodatella-like cells described by SWALE (1967) and FOTT (1968). The coenobial cells elongate, adhere to one another and each of the two outmost cells forms two spines (SMITH, 1914).  相似文献   

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Both diploid and tetraploid experimental interspecific hybrids betweenRanunculus silerifolius (2x) andR. chinensis (2x) exhibit normal bivalent pairing. However, microspores of diploid hybrids do not undergo mitosis and their pollen grains are highly sterile, whereas tetraploid hybrids form good pollen grains after microspore division. Evidence is forwarded for the assumption thatR. cantoniensis (4x) has originated by hybridization between these two diploid parental species and by polyploidization of the diploid hybrids. Parallelisms between the different karyotypes ofR. cantoniensis (4x) andR. silerifolius (2x) suggest that the former is a species of polyphyletic origin.  相似文献   

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The authors describe and illustrate two trematodes from Belize (Central America): Paramaritremopsis solielangi n. sp. from the small intestine of Arenaria interpres is characterised by a body length of 478 m, two short and pre-acetabular caeca, part of the uterus in close association with the cirrus-sac and left caecum, vitelline glands in the shape of a horseshoe, a short pre-ovarian cirrus-sac containing a long, cylindrical, voluminous and unarmed cirrus (size when evaginated: 150×20–30 m) and Microphallus kinsellai n. sp. from the caeca of Actitis macularia characterised by a body length of 370 m and a phallus which is 30 m in diameter and asymmetrical (basically a pad with a moderately developed accessory lobe) and a straight ejaculatory canal. Levinseniella carteretensis is another microphallid recovered from Arenaria interpres. The term of ``phallus' is proposed to name the male copulatory organ which characterizes the Microphallinae.  相似文献   

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