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。     

Toxoplasma gondii: ultrastructure and antigenicity of purified tachyzoite pellicle.

When purified Toxoplasma gondii tachyzoites were treated with hemolysin, DNase, and RNase, the organisms yielded a three-component system containing the outer membrane (pellicle), microtubules, and conoid in relatively normal morphological configuration. Further treatment of this preparation with protease digested all but the pellicle which was more collapsed in appearance. These two preparations were used in rabbit anti-toxoplasma and goat anti-rabbit ferritin labeling experiments. The three-component system showed ferritin label on the conoid and equal ferritin label on the outer and inner surfaces of the pellicle. The microtubules were unlabeled. The pellicle after protease treatment was labeled equally on its outer and inner surfaces, which indicated that the rabbit anti-toxoplasma serum contained antibodies against antigens on the outer and inner surfaces of the pellicle.     

Ultrastructure of In Vivo-Produced Caryocysts Containing the Coccidian Caryospora bigenetica (Apicomplexa: Eimerüdae)

A cotton rat was inoculated orally with oocysts of Caryospora bigenetica from the feces of a rattlesnake. Sixteen days later the rat was euthanized, and portions of the scrotum, foot pad and muzzle were processed for histological sections and transmission electron microscopy. Sporozoites within caryocysts had typical coccidian features such as an anterior and posterior refractile body, centrally located nucleus, micronemes, rhoptries, a conoid, a micropore near the anterior refractile body, a posterior pore, amylopectin granules, lipid bodies, a Golgi-like body, a mitochondrion and subpellicular microtubules. The infected host cell was spherical and surrounded by a fibrous wall-like covering, 0.35–1.00 μm thick. This outer covering, when viewed in stained histological sections, was periodic acid-Schiff (PAS)-positive.     

Calcium Entry in Toxoplasma gondii and Its Enhancing Effect of Invasion-linked Traits

During invasion and egress from their host cells, Apicomplexan parasites face sharp changes in the surrounding calcium ion (Ca²⁺) concentration. Our work with Toxoplasma gondii provides evidence for Ca²⁺ influx from the extracellular milieu leading to cytosolic Ca²⁺ increase and enhancement of virulence traits, such as gliding motility, conoid extrusion, microneme secretion, and host cell invasion. Assays of Mn²⁺ and Ba²⁺ uptake do not support a canonical store-regulated Ca²⁺ entry mechanism. Ca²⁺ entry was blocked by the L-type Ca²⁺ channel inhibitor nifedipine and stimulated by the increase in cytosolic Ca²⁺ and by the specific L-type Ca²⁺ channel agonist Bay K-8644. Our results demonstrate that Ca²⁺ entry is critical for parasite virulence. We propose a regulated Ca²⁺ entry mechanism activated by cytosolic Ca²⁺ that has an enhancing effect on invasion-linked traits.     

Brief communication: coracoclavicular joint in Northwest Indians

The incidence of an articular facet on the conoid tubercle of the clavicle indicating the presence of a coracoclavicular joint was studied in paired clavicles obtained from 1,000 adult subjects aged 18 to 95 years (748 males, 252 females), and 75 children (45 males, 30 females) of known age on whom a medicolegal postmortem had been performed by the second author during 1972-90. The subjects were inhabitants of northwest India. In addition, paired clavicles from 50 neonates and 35 fetuses were also examined. The facet was absent in the fetuses, neonates, and young children. The youngest clavicle showing the facet was from a girl of 13 years, in which it was present bilaterally. In adults the incidence of the facet was 10.1% (bilateral 5.7%, unilateral 4.4%) in males and 8.3% (bilateral 3.6%, unilateral 4.8%) in females. Absence of the facet in the fetuses, neonates, and young children shows that it is not a congenital anomaly.