CONFOCAL ANALYSIS OF PRIMARY CILIA STRUCTURE AND COLOCALIZATION WITH THE GOLGI APPARATUS IN CHONDROCYTES AND AORTIC SMOOTH MUSCLE CELLS

Detyrosinated and acetylated α-tubulins represent a stable pool of tubulin typically associated with microtubules of the centrosome and primary cilium of eukaryotic cells. Although primary cilium—centrosome and centrosome—Golgi relationships have been identified independently, the precise structural relationship between the primary cilium and Golgi has yet to be specifically defined. Confocal immunohistochemistry was used to localize detyrosinated (ID5) and acetylated (6-11B-1) tubulin antibodies in primary cilia of chondrocytes and smooth muscle cells, and to demonstrate their relationship to the Golgi complex identified by complementary lectin staining with wheat germ agglutinin. The results demonstrate the distribution and inherent structural variation of primary cilia tubulins, and the anatomical interrelationship between the primary cilium, the Golgi apparatus and the nucleus. We suggest that these interrelationships may form part of a functional feedback mechanism which could facilitate the directed secretion of newly synthesized connective tissue macromolecules.     

Relationships between parasitoid host range and host defence: a comparative study of egg encapsulation in two related parasitoid species

Abstract. Parasitoid host range may proceed from traits affecting host suitability, traits affecting parasitoid foraging behaviour, or both. We tested the hypothesis that encapsulation can be used as a reliable indicator of parasitoid host range in two closely related larval endoparasitoids of Lepidoptera. Cotesia glomerata (L.) (Hymenoptera: Braconidae) is gregarious and a generalist on several species of Pieridae, whereas C. rubecula (Marshall) is solitary and specific to Pieris rapae (L.). We determined the effects of host species ( Pieris brassicae (L.), P. napi (L.) and P. rapae ) (Lepidoptera: Pieridae) and host developmental stage (early first, second and third instar) on encapsulation of parasitoid eggs. Host species and parasitoid species, as well as the resulting interaction between these two factors had significant effects on encapsulation of Cotesia eggs. Encapsulation in Pieris hosts was much lower for C. glomerata (<34%, except for second and third instar of P. rapae ) than for C. rubecula (>32%), even when the latter was parasitizing P. rapae. Encapsulation increased with the age of the larvae, although the only significant difference was for C. glomerata. Overall, P. rapae showed a stronger encapsulation reaction than P. brassicae and P. napi. Encapsulation levels of C. glomerata corresponded well to patterns of female host species and host age preference for oviposition and parasitoid larval performance. In contrast, percentages of encapsulation of C. rubecula were not consistent with host preference and host suitability. We argue that encapsulation alone is unlikely to provide a sufficient explanation for C. glomerata and C. rubecula host range.     

ANATOMY OF SOME INDO-PACIFIC ELYSIIDAE (OPISTHOBRANCHIA: SACOGLOSSA (=ASCOGLOSSA)), WITH A DISCUSSION OF THE GENERIC DIVISION AND PHYLOGENY

The Elysiidae is the largest family of Sacoglossa (=Ascoglossa)(Mollusca, Opisthobranchia). The Indo-Pacific fauna containsabout 65 species presently referred to the genus Elysia. Almostnothing is known about the internal anatomy of these animals.In the present study the internal anatomy, particularly thepharyngeal musculature, morphology of radularteeth, and reproductivesystems, of 12 Indo-Pacific elysiids is investigated. Also,the internal anatomy of the Mediterranean type species of thegenera Elysia and Thuridilla is described. On this basis, thevalidity of the genera Elysia, Thuridilla, Elysiella and Pattyclaya,is confirmed. Also, the genus Placobranchus is transferred tothe Elysiidae. phylogenetically important characters are identifiedand phylogenetic relationships within the family are discussed. (Received 10 April 1991; accepted 28 December 1991)     

Comparison of Mitomycin C and X-irradiation as Blocking Agents in One-way Mixed Leucocyte Cultures

THE mixed leucocyte culture (MLC) test^1,2 has been widely used as a measure of histocompatibility in man and as a model for the recognition phase of the homograft response in vitro. Two methods have been proposed to achieve unidirectional stimulation in MLC: treatment of stimulating cells with either mitomycin C³ or X-irradiation³. The mitomycin C method has the advantage of not requiring expensive X-ray equipment and being immediately available in the laboratory; the X-ray method has the advantage of not requiring washing of the cells following treatment. Although much of the quantitative MLC work for histocompatibility testing in man has been done using mitomycin C, the general impression gained from the literature as well as the studies we report here would support the use of either method. A previous study⁴ suggested that irradiation is superior to mitomycin C treatment for a number of reasons, but we question those conclusions.     

The Mitochondrion of Plasmodium falciparum Visualized by Rhodamine 123 Fluorescence1

Rhodamine 123 (Rh 123) has been used to probe the functional status of the mitochondrion present within the asexual, intraerythrocytic stages of the malarial parasite Plasmodium falciparum. This cationic fluorescent dye accumulates specifically in negatively charged cellular compartments, such as mitochondria. Using epifluorescence microscopy the development of what appears to be a single mitochondrion has been followed through the intraerythrocytic cycle. Mitochondrial development progresses from a fine thread-like organelle that becomes longer and eventually branched. Each daughter merozoite receives a branch or piece of the parent organelle. Cytoplasmic Rh 123 accumulation was also observed, indicating that there exists a transmembrane potential across the outer plasma and parasitophorous vacuolar membranes of the parasite. The effects of uncouplers (protonophores), ionophores, and inhibitors were examined by monitoring Rh 123 accumulation and retention. Our results demonstrate that the mitochondrion of P. falciparum actively maintains a high transmembrane potential, the function of which is as yet undefined.     

A New Pathogen,Microsporidium itiiti n. sp. (Microsporida), from the Argentine Stem Weevil,Listronotus bonariensis (Coleoptera,Curculionidae)1

A new species of microsporidium (phylum Microspora) infecting the Argentine stem weevil, Listronotus bonariensis (Kuschel. 1955), is described on the basis of light and electron microscope observations. It has the following characteristics: nuclei always isolated; meronts spherical and sporonts ribbon-shaped, with variable numbers of nuclei; sporogony within a vacuole which is bounded by a thin membrane that usually breaks down before uninucleate spores mature; occasionally parts of the membrane remain so that clusters of variable numbers of spores may be seen in light microscopic preparations. Spores measure 2.5 × 1.4 μm (fresh) and development occurs mainly in the midgut, but also in the epidermis, fat body, muscle, and ovaries.     

Furrows and firmgrounds: evidence for predation and implications for Palaeozoic substrate evolution in Rusophycus burrows from the Silurian of New York

Tarhan, L.G., Jensen, S. & Droser, M.L. 2011: Furrows and firmgrounds: evidence for predation and implications for Palaeozoic substrate evolution in Rusophycus burrows from the Silurian of New York. Lethaia, Vol. 45, pp. 329–341. The Silurian Herkimer Formation of east‐central New York contains abundant, exceptionally preserved composite Rusophycus‐Teichichnus burrows. We suggest that the most likely interpretation of these composite trace fossils is as structures formed by trilobites entering the sediment in search of prey. Parallel alignment of the paired traces, asymmetrical configuration of the Teichichnus along the longitudinal axis of the associated Rusophycus, depth correlation and deformation of the Teichichnus all suggest that this relationship was predatory. In addition, sectioned material indicates that these Rusophycus may have been open at the sediment‐water interface, while the crisp preservation of both Rusophycus and Teichichnus, along with the preservation of such delicate morphological details as scratch marks, suggests that the sediment must have been relatively firm at the time the traces were formed. The formation and preservation of Rusophycus in cohesive sediments located very close to the sediment‐water interface hold important implications for the manner in which we consider Palaeozoic substrates and their temporal and spatial evolution. Moreover, these findings demonstrate that the morphology and taphonomy of ichnological associations may, in the context of sedimentological relationships, prove a powerful proxy for tracking substrate conditions through both space and time. □firmgrounds, New York, predation, Rusophycus, substrate, taphonomy.