广东肝血簇虫在宿主内脏裂体生殖时期超微结构的研究

本文详细描述了广东肝血簇虫(Hepatozoon guangdongensis)在实验宿主、中国水蛇肺部裂体生殖整个发育过程各期虫体的超微结构。成熟裂殖体内的裂殖子与肺部毛细血管内皮细胞内的裂殖子的超微结构是相似的。裂殖子(3.4×1.3μm)外被由外膜和内膜构成的表膜,它与球虫一样具有包括类锥体在内的完全顶复结构。内皮细胞内的裂殖子和滋养体都没有围虫泡和围虫泡膜包绕。具有内膜的长形滋养体变圆,并外被由宿主细胞产生的围虫泡和围虫泡膜包绕,转变成为圆形的幼期裂殖体,然后发育成为成熟的裂殖体。成熟裂殖体(23×10μm)内含30—50个裂殖子。裂殖体内没有观察到残余体存在。     

中华血簇虫的生活史研究(复顶门:孢子纲) Ⅱ.中华血簇虫在中华鳖中的发育

中华血簇虫在其无脊椎动物寄主中的发育已另有文描述。这里报道的是中华血簇虫在中华鳖中的发育。这一时期包括三个阶段:组织细胞内裂体增殖、深部血红细胞内的裂体增殖和外周血红细胞内的裂体增殖。组织细胞内裂殖体产生14—32个裂殖子。深部血红细胞内的裂殖体分为两类:一类是X裂殖体,它产生14—18个小裂殖子;另一类是Y裂殖体,它产生4—6个大裂殖子。外周血红细胞内的初期裂殖体可产生多至14个裂殖子,而随后的裂体增殖却产生越来越少的裂殖子,且裂殖体和裂殖子的大小也渐趋变小。外周血晚期的裂殖体只形成2个裂殖子。配子母细胞来源于Y裂殖子。营养体是由上一代裂殖子向下一代裂殖体发育的中间时期。     

家兔艾美虫

动物学实验中常以疟原虫(Plasmodium)或单房簇虫(Monocystis)作为孢子虫纲的代表。黄咸凤同志在生物学通报1963年第4期发表“兔球虫的实验观察法”一文,介绍改用兔球虫作为孢子虫纲的代表,我们很赞同。因为兔球虫的确是孢子虫纲典型的代表,它的生活史显著地包括裂体生殖(即由营养体形成裂殖子的过程)、配子生殖(包括配子形成和结合成合子的过程)和孢子生殖(即由合子形成子孢子的过程)三个     

贝氏隐孢子虫在北京鸭体内发育的超微结构研究

贝氏隐孢子虫各期虫体均位于宿主粘膜上皮细胞的带虫空泡中。在虫体与上皮细胞接触处,虫体表膜反复折迭形成营养器。子孢子或裂殖子与粘膜上皮细胞接触后,逐步过渡为球形的滋养体;滋养体经2—3次核分裂、产生含4或8个裂殖子的两代裂殖体,裂殖体以外出芽方式产生裂殖子;裂殖子无微孔,顶端表皮形成3—4个环嵴,裂殖子进一步发育成为配子体;大配子体含有两种类型的成囊体。小配子呈楔形,无鞭毛和顶体,有一个致密的长椭圆形细胞核,小配子表膜内侧有9根膜下微管;孢子化卵囊内含四个裸露的子孢子和一个大残体。本文是有关鸭体内隐孢子虫超微结构的首次报导。     

肝血簇虫属一新种记述(真球虫目、血簇虫科)

国外研究肝血簇虫Hepatozoon已有近80年历史,从哺乳类、鸟类和爬行类中描述了近80个种Levine,1980。我国只有Nauck 1927在松鼠Sciurus vulgaris的外周血液中观察到Hepatozoon sp.的寄生,但既没有描述也没有命名。作者在1980年6月到1981年7月,对来自广东各地的81条灰鼠蛇Plyas korras进行血检,发现其中5条感染     

广东艾美虫发育的研究

广东艾美虫寄生于乌鳢的消化道,其发育周期可分为裂体生殖、配子生殖和孢子生殖三个阶段。这三个阶段均在一个寄主体内完成。裂体生殖和配子生殖发生在幽门盲囊和前肠上皮细胞核之上方。成熟裂殖体为球形或椭圆形,含有8—14个香蕉形裂殖子。大配子的整个发育过程没有发现嗜伊红颗粒,嗜碱性颗粒在卵囊壁形成前后发生变化。成熟小配子母细胞内有许多新月形的小配子。孢子生殖在幽门盲囊和整条肠管内进行。       

中华血簇虫的生活史研究 Ⅰ.中华血簇虫在鳖穆蛭中的发育

中华血簇虫是湖北产的中华鳖体内发现的一种寄主虫。在其生活史发育中,存在着两种寄主的交替。本文只介绍它在无脊椎动物寄主——鳖穆蛭体中的发育情形。这一时期包括两个阶段:配子生殖和孢子生殖。配子生殖的特点是,两性配子母细胞先融合,然后才进行配子分化,产生4个雄配子核,其中1个核与雌配子核受精,形成合子核。孢子生殖以单核卵囊的核分裂开始,最后形成含8个裸子孢子的成熟卵囊,并解体释放出子孢子。整个过程都发生在蛭消化道内。脊椎动物寄主的感染,很可能是因为吃下含成熟子孢子的无脊椎动物寄主而引起的。     

毁灭泰泽球虫Tyzzeria Perniciosa(Sporozoa:Eimeriidae)生活史各阶段的细胞化学研究:Ⅰ.多糖

本实验分别用过碘酸——雪夫氏剂染色方法(PAS)和乌洛托品——硝酸银染色方法在光镜和电镜下检验毁灭泰泽球虫生活史各时期体内的多糖及其分布。实验结果表明,子孢子内、各代裂殖体和裂殖子内都含有多糖。大配子和合子内除含有多糖外还含有成囊颗粒。成囊颗粒的成分是糖蛋白。无性世代的滋养体和多核体内未检出多糖。早期配子细胞,小配子体和小配子内也未检出多糖。本实验证明,毁灭泰泽球虫体内的多糖系由其自身合成,并在其发育过程中消耗。     

贝氏隐孢子虫在鸡体内发育的形态学特征及其对寄生器官的影响

取 2日龄海兰雏鸡 5 0只 ,分为 5组 ,分别接种 0、 0 8× 10 6、 1 6× 10 6、 3 2× 10 6、 6 4× 10 6个鸭源贝氏隐孢子虫 (Cryptosporidiumbaileyi)卵囊。接种后在不同的时间间隔内剖杀雏鸡 ,取法氏囊、气管和喉头。扫描电镜观察发现贝氏隐孢子虫主要寄生在鸡的喉头、法氏囊、气管。裂殖体有 2种类型 :Ⅰ型裂殖体含 8个裂殖子 ,Ⅱ型裂殖体含 4个裂殖子。子孢子或裂殖子在钻入过程中 ,虫体逐渐由香蕉形过渡到鼓槌形 ,最后形成球形的滋养体。带虫空泡分为有球形残体的带虫空泡和无球形残体的带虫空泡。观察到小配子的释放和虫体寄生于杯状细胞的现象。贝氏隐孢子虫寄生于气管引起纤毛倒伏、排列紊乱、纤毛融合、脱落 ;致使法氏囊上皮肿胀 ,法氏囊粘膜表面形成皱褶 ,微绒毛脱落、融合、排列紊乱 ,粘液性分泌物增多 ,炎性细胞渗出     

微小泰泽球虫内生阶段虫体内多糖的细胞化学的研究

采用纯种微小泰泽球虫(Tyzzeria parvula)卵囊,人工感染四日龄雏鹅,定时剖杀,取肠道组织进行石蜡切片,细胞化学染色,观察微小泰泽球虫内生阶段虫体内多糖的分布。结果表明:滋养体、多核体、小配子体以及早期的大配子体内均不含多糖。裂殖子PAS反应阳性,但也有少数第二代裂殖子阴性。随着大配子体的发育,多糖逐渐在其体内合成,合子时期达到高峰。提示:微小泰泽球虫体内的多糖是一个合成—积累—消耗的过程。     

Hepatozoonosis in foxes from Portugal

Hepatozoon, sp. is described for the first time in foxes (Vulpes vulpes silacea) in Portugal. Of 301 foxes examined, 143 (48%) were infected. The gametocyte was the predominant stage of the life cycle and was found in every organ except the bone marrow, where schizonts were the most abundant stage. The morphological similarity of this parasite's gametocytes to Hepatozoon canis is emphasized.     

Intraerythrocytic development of species of Hepatozoon infecting ranid frogs: evidence for convergence of life cycle characteristics among apicomplexans

Intraerythrocytic development of the adeleorin apicomplexans Hepatozoon clamatae and Hepatozoon catesbianae were investigated in the bullfrog, Rana catesbeiana, the green frog, Rana clamitans melanota, and the Northern leopard frog, Rana pipiens. Merozoites emerging from hepatic meronts penetrated erythrocytes and underwent 1-3 rounds of binary fission to produce 2-8 merozoites. Following their release from infected erythrocytes, individual merozoites entered new cells and transformed into gamonts. Although this is the first report of intraerythrocytic development for a fully described species of Hepatozoon, a phylogenetic reanalysis of 11 species of Hepatozoon, 6 species representative of the 5 other hemogregarine taxa, 2 species of dactylosomatids, and 2 species of piroplasms, indicates that asexual reproduction of parasites within blood cells of vertebrates has arisen at least 3 times in the apicomplexan lineage that includes adeleorins and piroplasms. This method of asexual development, which is also observed in species of hemospororin genera such as Plasmodium, is discussed in the context of the evolution of apicomplexan life cycles. In addition to supporting the paraphyly of the genus Hepatozoon determined in an earlier study, this phylogenetic analysis featured a monophyletic group, consisting of the sister taxa Hemolivia and Karyolysus, that was the sister group to a clade consisting of the more derived hemogregarines, the dactylosomatids, and the piroplasms.     

Molecular characterization of an ancient Hepatozoon species parasitizing the 'living fossil' marsupial 'Monito del Monte' Dromiciops gliroides from Chile

The Microbiotheriid Dromiciops gliroides , also known as 'Monito del Monte', is considered to be a threatened species and the only living representative of this group of South American marsupials. During the last few years, several blood samples from specimens of 'Monito del Monte' captured at Chiloé island in Chile have been investigated for blood parasites. Inspection of blood smears detected a Hepatozoon species infecting red blood cells. The sequences of DNA fragments corresponding to small subunit ribosomal RNA gene revealed two parasitic lineages belonging to Hepatozoon genus. These parasite lineages showed a basal position with respect to Hepatozoon species infecting rodents, reptiles, and amphibians but are phylogenetically distinct from Hepatozoon species infecting the order Carnivora. In addition, the Hepatozoon lineages infecting D. gliroides are also different from those infecting other micro-mammals living in sympatry, as well as from some that have been described to infect an Australian species of bandicoot. The potential vector of this parasite appears to be the host-specific tick Ixodes neuquenensis because the sequencing of a long amplicon determined the presence of one of the two lineages found in the marsupial.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 568–576.     

A Hepatozoon species genetically distinct from H. canis infecting spotted hyenas in the Serengeti ecosystem, Tanzania

Health monitoring of spotted hyenas (Crocuta crocuta) in the Serengeti ecosystem, Tanzania, revealed Hepatozoon infection in all of 11 immature individuals examined following death from natural causes. Hepatozoon infection was probably an important factor contributing to mortality in two cases that exhibited clinical signs of ataxia, lethargy, ocular discharge, retching, and labored breathing before death. Whether Hepatozoon infection contributed to six deaths from fire, probable lion predation and unknown causes could not be determined. Four deaths from infanticide and starvation were unlikely to be associated with Hepatozoon infection. Histologic examination revealed lung tissue infected with cyst-like structures containing protozoan stages in all eight cases examined and interstitial pneumonia in most cases. Systemic spread of infection to several organs was found in three cases. Alignment of a 426 bp sequence from the parasite's 18s rRNA gene revealed a Hepatozoon species identical to that recently described from two domestic cats in Spain and only 7 bp substitutions when a 853 bp sequence was aligned to this cat Hepatozoon species. Previous reports of infection of wild carnivores in eastern and southern Africa with an unspecified Hepatozoon species similar in appearance to H. canis may have involved the species described in this study.     

Characterization of CD34+ cells isolated from human fetal lung

The large capillary mass of the newborn lung demands the presence of endothelial cell precursors in lung tissue before development of the pulmonary capillary bed. The objective of this investigation was to isolate and characterize putative endothelial cell precursors from developing human lung. CD34, a cell surface marker for hematopoietic progenitor cells, endothelial precursor cells, and small vessel endothelial cells, was employed as an immunological "handle" for the selection of the desired cells. When CD34+ cells were isolated from midtrimester human fetal lung tissue, then maintained in culture, the isolated cells expressed immunoreactivity for the endothelial cell marker von Willebrand factor and the vascular endothelial growth factor receptors KDR and Flt-1. However, only 5% or fewer of the cells expressed PECAM, an important factor in cell-cell interactions and a marker for endothelial cells associated with vessels. The CD34+ cells endocytosed acetylated low-density lipoprotein and formed capillary-like structures when incubated in a cushion of Matrigel. RT-PCR analysis of mRNA for endothelial cell-related proteins Flt-1, Tie-2, and endothelial nitric oxide synthase demonstrated expression of these mRNAs by the isolated cells for at least 16 cell passages. These observations demonstrate that capillary endothelial cell precursors can be isolated from developing human lung and maintained in cell culture. These cells represent a potentially important tool for investigating the regulation of mechanisms governing development of the air-blood barrier in the human lung.     

Haemogregarina nototheniae n. sp., from the blood of Antarctic nototheniids

A new species of haemogregarina, Haemogregarina nototheniae, is described from the Southern ocean teleosts Notothenia neglecta and Notothenia rossii. Stages identified as macro- and microschizogony and gametogony are described in mononuclear leukocytes from fish caught during the austral summer. The mature gametocyte is the most commonly found stage: it is exoerythrocytic, but carries the host erythrocyte nucleus attached to its external surface near one end. The gametocyte has a central nucleus and 2–16 subterminal eosinophilic granules, but no polar cap. During microschizogony the schizont nucleus undergoes repeated division without cytoplasmic division to give 32 nuclear masses, all of which appear to be in metaphase. Cytoplasmic division yields free merozoites identifiable by the coarse chromatin of the nuclear area. During macroschizogony the intraleukocytic parasite swells to a subspherical mass with a median band of fine heterochromatin granules. The cytoplasm later divides, forming three merozoites. There appear to be two routes by which merozoites proceed to become gametocytes: in winter small merozoites are seen in mature erythrocytes; but in summer, in erythroblasts. The invertebrate definitive host and the means of transmission are unknown, but the parasite is provisionally assigned to the genus Haemogregarina.     

The malarial parasites of Anolis species (Sauria: Iguanidae) in Panama

Lizards of the iguanid genus Anolis in Panama are parasitized by four species of Plasmodium. P.floridense occurs in A. limifrons, A. biporcatus, A. pentaprion and A. frenatus. The number of nuclei in mature schizonts is influenced by host species as is gametocyte shape but not gametocyte size. P. tropiduri parasitizes A. limifrons, A. pentaprion, A. biporcatus, A. frenatus, A. lionotus and A. poecilopus. The number of nuclei in schizonts varies according to host and type of blood cell parasitized. Gametocyte size varies slightly by host but shape remains relatively constant. Position of the parasite in the host cell may be affected by host species. Both schizonts and gametocytes are produced in white cells of all host species studied. P. balli occurs in A. limifrons, A. lionotus and A. poecilopus. Schizont and gametocyte size and shape are affected by host and blood cell type, with the parasite exhibiting different preferences for various blood cells in each host. P. minasense parasitizes A. limifrons, A. frenatus and A. capito, but its diagnosis in the last species may not be correct as gametocyte size and distribution of pigment differ considerably from other hosts. The mean number of nuclei in schizonts is not greatly affected by the host species. P. floridense is postulated to be of middle American origin in the genus Anolis, and to have reached Florida through the Caribbean.     

Influence of maternal diabetes on basement membranes, type 2 cells, and capillaries in the developing rat lung

To determine the effect of maternal diabetes on rat lung development, we studied the ultrastructure of the alveolar wall from the ninteenth day of gestation (term = 22 days) through the eighth postnatal day in fetal and neonatal rats of mothers with streptozotocin-induced diabetes. In normal fetal lung development, epithelial basement membranes develop large discontinuities beneath type 2 cells, through which cytoplasmic foot processes extend into the interstitium. Maternal diabetes delays the appearances of these epithelial basement membrane discontinuities and reduces the number of type 2 cell processes that penetrate it. These alterations in epithelial basement membrane are reversed after birth. There is no ultrastructural evidence of a delay in type 2 cell maturation as assessed by lamellar body volume density morphometry. Endothelial basement membranes, which are not present around the growing pulmonary capillary bed in the pseudoglandular lung, are seen late in normal gestation, primarily around capillaries forming the mature air-blood barrier. This development of endothelial basement membrane may be delayed in the fetuses of diabetic mothers and reflects a significant delay in the expansion of the pulmonary capillary network in these animals as assessed by morphometric volume density measurements. This effect on capillary growth is not reversed in the newborn animals through 8 days after birth. The summation of these effects indicates a generalized slowing of fetal lung development by maternal diabetes, some of which effects persist after birth and may continue to influence lung development during the period of postnatal alveolar septal growth.     

Molecular characterization of the 18S rDNA gene of an avian Hepatozoon reveals that it is closely related to Lankesterella

As a part of intensive study of blood parasite infections in a population of the passerine bird blue tit (Cyanistes caeruleus, Paridae), we detected a parasite species that, based on its morphological similarity, was tentatively identified as Hepatozoon parus, the only species of this parasite genus described from birds of this family. However, morphological measurements show that H. parus is slightly larger than the parasite detected in our population. A molecular characterization of the parasite species was conducted by amplification of the 18S rDNA gene, using primers that were reported previously to amplify in Hepatozoon sp. of water pythons. Additional primers were developed based on the new sequence obtained. The 1,484-bp fragment amplified reveals that the parasite from our bird population is more closely related to Lankesterella minima than to Hepatozoon species from other vertebrates according to analysis using the BLAST comparison method (93% identity). In addition, phylogenetic analyses using parsimony and Kimura procedures unequivocally related the parasite species detected by PCR with L. minima. The bootstrap values obtained were 97% and 100%, respectively. These results imply that this parasite is a species of a lankesterellid instead of Hepatozoon.     

A new species of Hepatozoon (Apicomplexa: Adeleorina) from Python regius (Serpentes: Pythonidae) and its experimental transmission by a mosquito vector

Hepatozoon ayorgbor n. sp. is described from specimens of Python regius imported from Ghana. Gametocytes were found in the peripheral blood of 43 of 55 snakes examined. Localization of gametocytes was mainly inside the erythrocytes; free gametocytes were found in 15 (34.9%) positive specimens. Infections of laboratory-reared Culex quinquefasciatus feeding on infected snakes, as well as experimental infection of juvenile Python regius by ingestion of infected mosquitoes, were performed to complete the life cycle. Similarly, transmission to different snake species (Boa constrictor and Lamprophis fuliginosus) and lizards (Lepidodactylus lugubris) was performed to assess the host specificity. Isolates were compared with Hepatozoon species from sub-Saharan reptiles and described as a new species based on the morphology, phylogenetic analysis, and a complete life cycle.