An ultrastructural study of the response of Blatella germanica (Orthoptera: Blattidae) to the nematode Abbreviata caucasica (Spirurida: Physalopteridae)

An ultrastructural study of the response of Blatella germanica (Orthoptera: Blattidae) to the nematode Abbreviata caucasica (Spirurida: Physalopteridea). International Journal for Parasitology4: 133–138. This study investigates the response of the roach, Blatella germanica L. to the invading spirurid nematode, Abbreviata caucasica v. Linstow. Soon after the first stage nematodes entered the epithelial cells of the colon wall, the surrounding host cells broke down into syncytial giant cells. Large polychromatic epithelial cell nuclei occurred throughout the giant cells and the nematodes moved freely within the cytoplasmic matrix. These giant cells were in turn surrounded by blood cells responding to the disruption. The nematodes developed to the infective third stage juveniles within the giant cells and ingested the syncytial cytoplasm. After reaching the third stage, the parasites remained in a quiescent state within the vacuolated cell which was surrounded by a double tissue layer.Evidence indicated that successful development of the parasite was dependent on the disrupted epithelial cells forming a giant syncytial cell which protected and supplied nourishment to the parasite.     

Observations on the Ultrastructure of Uronema spp., Marine Scuticociliates*

SYNOPSIS. Observations of the ultrastructure of marine scuticociliatids, tentatively assigned to the genus Uronema, were made by light, transmission electron, and scanning electron microscopy. Giant, cortically oriented mitochondria filled the subpellicular, intermeridional areas, and were in close association with the epiplasm immediately under the inner alveolar sac membranes. Reconstructions of serial sections of the posterior poles of ciliates indicated that the intermeridional mitochondria could fuse at that point and the entire chondriome might at times be a single organelle. A system of tubules was observed to be intimately associated with the mitochondria in the posterior region. The tubules anastomosed and were directed posteriorly into the region of the nephridial-contractile vacuole system. The outer surfaces were coated with projections arranged in helical patterns. The system may be regarded as a fluid segregation organelle. The tripartite nature of the polar basal body complex observed by silver impregnation was confirmed by transmission electron microscopy. The 3 structures were the basal body of the caudal cilium and 2 parasomal sacs. A prominent ring around the caudal cilium was observed by scanning electron micrcscopy; it is probably responsible for the silver deposition surrounding the polar basal body complex that can be seen by light microscopy of silver-impregnated specimens. The ultrastructure of the nonmotile caudal cilium and its kinetosome was unremarkable, being like that of the motile, somatic cilia. The micronuclear and macronuclear outer membranes were continuous at several sites. Such interconnections explain the intimate physical relationship between the nuclei during interphase in many ciliates, and could be a structural basis for chemical communication between the 2 nuclear types. Within the cytoplasm surrounding the opening of the cytoproct, numerous clear vesicles were observed. Their position and appearance suggested that the cytoproct may be involved in the elimination of solutions as well as solids. Food vacuoles, cortical microtubules, lamellar vesicles, disc-shaped vesicles, mucocysts, and a contractile vacuole and its pore were also observed.     

The role of glucose on the enzymes involved in the release of mature spores of Chlorella fusca

An enzyme with carbohydrate-releasing activity (CRA) plays a key role in the release of the mature autospores of Chorella fusca Shihira et Krauss var. vacuolata SAG 211-8B. CRA liberates oligomeric carbohydrates from isolated sprorangia walls and furthermore splits p -nitrophenyl-β- d -fucopyranoside. Observations on mixotrophically cultivated C. fusca and on isolated CRA indicated that in vitro the β- d -fucosidase activity is inhibited by glucose. In vivo glucose induces the well-known gigantism of the algal cells by blocking sporulation, and this leads to the formation of giant sporangia containing up to 128 spores. Glucose and fucose were the only inhibitors of CRA isolated from the homogenate of C. fusca cells.     

Measurements of amino acid transport in internally dialyzed giant axons

Summary It is shown that the axoplasmic composition of acidic and neutral amino acids can be controlled effectively by the method of internal dialysis. Direct assay for specific binding and measurement of diffusion coefficients in axoplasm show that there is no significant binding or compartmentalization of amino acids. The dependence of amino acid efflux on substrate concentration can be measured under well-defined, true steady-state conditions. The taurine efflux-concentration relation in theMyxicola giant axon conforms to a second-order Hill equation. This fact is consistent with either a cooperative process or a mechanism in which membrane translocation is not the rate-controlling step. The effluxes of taurine and glycine from squid axon are an order of magnitude smaller than inMyxicola. The efflux-concentration relations are essentially linear up to 200mm substrate concentration. This result may be produced by specific transporters which have very high asymmetry, or by simple diffusive leak in the absence of specific transporters.     

SEASONAL PRODUCTIVITY OF TWO RED ALGAE IN A CENTRAL CALIFORNIA KELP FOREST1

The in situ productivity of Botryocladia pseudodichotoma (Farl.) Kyl. and Rhodymenia californica var. californica Kyl., two common understory macrophytes in Macrocystis pyrifera (L.) C. Ag. forests, was determined once per month for one year. Gross productivity for B. pseudodichotoma was highest in October (1.23 mgC · g dry wt.^?1· h^?1), but rates were generally greater in spring and lower in summer. Respiration was variable throughout the year, especially in proportion to gross productivity. Gross productivity for R. californica var. californica was also highest in October (4.62 mgC · g dry wt.^?1· h^?1), and lowest in summer. Respiration was highly variable throughout the year. Deep (11 m) populations o/B. pseudodichotoma had 50% higher productivity than shallow (3 m) populations when incubated in shallow water, and 45% higher productivity when incubated in deep water. Populations of B. pseudodichotoma growing in shade at 3 m had 77% higher productivity than populations growing in sun at the same depth when incubated in a sun exposed location at 3 m. Respiration of the shade-adapted plants was only one-half that of the sun-adapted plants. In comparison with similar studies in other sub-tidal communities, net productivity of these two understory red algae is somewhat lower. Lack of strong seasonal productivity patterns and the highly variable underwater light regime suggests that understory algae may be adapted for rapid growth during short periods of high light, regardless of the time of year.     

Preliminary remarks on the characteristics of the rotifer fauna of Australia (Notogaea)

Unusually large forms of Asplanchna sieboldi, Brachionus plicatilis, B. calycijlorus, Filinia pejleri, Trichocerca similis and Keratella slacki were collected from waters of south-eastern Australia. These giant forms are figured, and brief location and ecological data are given. Although the rotifer fauna of the Murray riversystem contains pan-tropical and pan-subtropical species, there exists a greater degree of endemicity than previously considered.     

Field and laboratory studies on the fungus Aspergillus parasiticus, a pathogen of the pink sugar cane mealybug Saccharicoccus sacchari

Infestation of sugar cane nodes by the mealybug Saccharicoccus sacchari (Cockerell) was studied in two commercial fields over a 7-month period in 1987. Natural enemies associated with S. sacchari were fungi Aspergillus parasiticus Speare, Metarhizium anisopliae (Metschnikoff) Sorokin, and Penicillium spp.; the dipteran Cacoxenus perspicax Knab; and the hymenopteran parasitoid Anagyrus saccharicola Timberlake. A. parasiticus was the predominent natural enemy of S. sacchari whereas all other natural enemies showed a low level of activity. The highest prevalence of A. parasiticus was in March when it occurred on 84% of S. sacchari-infested nodes. The prevalence of A. parasiticus declined rapidly during April and May and was absent in the winter months during which nodal infestation of S. sacchari increased. In laboratory bioassays all fungal isolates originating from S. sacchari were more virulent at 28°C than at 24°C. Laboratory studies supported the hypothesis based on field observations that temperature highly influenced the efficacy of A. parasiticus against S. sacchari.     

The effect of carbon and nitrogen sources on bovicin HC5 production by Streptococcus bovis HC5

Aims:  To investigate the effect of media composition and agroindustrial residues on bovicin HC5 production by Streptococcus bovis HC5.
Methods and Results:  Batch cultures of S. bovis HC5 were grown in basal medium containing different carbon and nitrogen sources. The activity of cell-free and cell-associated bovicin HC5 was determined in culture supernatants and acidic extracts obtained from cell pellets, respectively. Streptococcus bovis HC5 produced bovicin using a variety of carbon and nitrogen sources. The highest specific activity was obtained in media containing 16 g l⁻¹ of glucose, after 16 h of incubation. The peak in cell-free and cell-associated bovicin HC5 activity was detected when S. bovis HC5 cultures reached stationary phase. The bovicin HC5 specific activity and bacterial cell mass increased approximately 3-fold when yeast extract and trypticase (0·5 and 1·0 g l⁻¹, respectively) were added together to the basal medium. Streptococcus bovis HC5 cultures produced bovicin HC5 in cheese whey and sugar cane juice and maximal volumetric productivity was obtained after 12 h of incubation.
Conclusions:  Streptococcus bovis HC5 is a versatile lactic acid bacterium that can utilize several carbon and nitrogen sources for bovicin HC5 production. This bacterium could be a useful model to study bacteriocin production in the rumen ecosystem.
Significance and Impact of the Study:  The use of agroindustrial residues as carbon sources could have an economical impact on bovicin HC5 production. To our knowledge, this is the first report to show the use of sugar cane juice for bacteriocin production by lactic acid bacteria.     

大熊猫的刻板行为及其矫正对策——丰富圈养环境举措

由于生活环境单一、活动空间狭小等阻碍了正常行为的表达,圈养大熊猫经常发生一种谓之“刻板行为”的机械、呆板行为。所谓刻板行为,是指圈养大熊猫无明显目的的、不变的、以固定频率反复重复的无任何功能效果的简单行为。丰富圈养环境举措(环境富集)是矫正刻板行为的一种重要的行之有效的对策。介绍了圈养大熊猫刻板行为的表现、特点、发生机制及富集化矫正对策。     

Phylogeography of the giant wood spider (Nephila pilipes, Araneae) from Asian–Australian regions

Aim There are currently few population genetic studies on widely distributed SE Asian terrestrial organisms. We have studied the genetic diversification pattern of the giant wood spider, Nephila pilipes (Araneae: Tetragnathidae) to see whether fluctuations in rain forest extents generated by Quaternary climatic changes left signatures on populations of this agile terrestrial arthropod. Location The collecting localities were distributed in the following seven regions: (1) N Australia; (2) India (Calcutta, Karziranga and Sukna); (3) SE Asia (N Vietnam, Malaysia, Singapore and Bali); (4) SE China (Fujian, Guandong, Hong Kong and Hainan); (5) SW China (Guangxi and Yunnan); (6) E Asian islands (Ryukyu islands and Taiwan); and (7) the Philippine Islands. Methods A total of 374 specimens were collected from the East Asian continent and islands, SE Asia, India, and northern Australia. Mitochondrial cytochrome oxidase I gene partial sequences were used as the molecular marker to infer the phylogeographic diversification patterns. Results From the specimens collected, 67 haplotypes were identified, which could be grouped into five major clades. The dominant clade contained populations in regions ranging from Okinawa to Bali (spanning a distance of more than 4000 km), but their genetic variations were not structured and were not significantly associated with geographical distances. Three clades contained specimens collected from peripheral regions of the distribution range of N. pilipes, such as India, N Australia, and NE Asia. Members of the clade distributed in NE Asia were sympatric but those of the clades distributed in Australia and India were allopatric with those of the dominant clade. Main conclusions The results of this study indicate that, during Quaternary glacial periods, the rain forests in SE Asia might have been more or less continuous and thus generated an unstructured genetic diversification pattern of N. pilipes inhabiting this region. However, during such periods, populations in peripheral regions such as India, N Australia and NE Asia might have been isolated in refugia, thus accounting for the observed genetic divergence from populations in the SE Asian region.