Structure and reproduction of Hormidiella bharatiansis sp. nov.

The structure and reproduction of Hormidiella bharatiansis sp. nov. is described. Asexual reproduction is by zoospores: sexual reproduction is by morphologically similar gametes, some of which, after a brief period of swarming, settle down, round off, enlarge and act as females gametes, the others remaining active and functioning as male gametes. Fertilisation takes place about six to eight hours after liberation: one to two percent of the zygotes are abortive.     

Adolescence and the Reversibility of Maturity in Euplotes crassus

ABSTRACT. The clonal life history of ciliated protists is characterized by a sequence of phenotypes; sexual immaturity, maturity, and senescence. The distinctiveness of immaturity and maturity has been investigated. Standard assays of the onset of maturity of progeny clones from a cross between stocks EC1 and EC2 of Euplotes crassus demonstrated significant differences among clones and among testers within clones. They also revealed that the first positive test(s) of a progeny subclone were typically followed by at least one negative test. Special protocols were devised to investigate if maturity was reversible at the cellular level. In these experiments, the first mating pair of a progeny subclone was split before the consummation of mating. From these two cells as well as from control progeny and tester cells, subclones were established and every leftover cell was tested for maturity after each transfer. Both standard and split-pair progeny subclones had immature and slow- to-mate cells. The number of fissions before progeny exhibited sexual behavior indistinguishable from the testers was more than twice that to the first mating reaction of a subclone. At the first sign of maturity, progeny lines are a heterogeneous population of cells able and not able to mate, but remarkably, clonal descendants of those able to mate may become unable to mate. The development of maturity is progressive, quantitative and non-monotonic rather than an instantaneous switch.     

Inertia of parasite infection versus host biomass fluctuation

Infection by parasites with complex life cycles such as trematodes depends on many environmental factors which may result in a time-lag between host biomass fluctuations and parasite density in hosts. A cockle (marine bivalve, second intermediate host) population and its associated parasite community were monitored over 15 years. A time-shift correlation analysis suggests that trematode abundance in cockles responds to cockle biomass after a long delay (8 year time-lag). Thus, these parasites can sustainably support a deficit of their intermediate host.     

Ultrastructural Study of the Development of Pleistophora schubergi Zwölfer, 1927 (Protozoa,Microsporida) in Larvae of the Spruce Budworm,Choristoneura fumiferana and Its Subsequent Taxonomic Change to the Genus Endoreticulatus

This study demonstrates that Pleistophora schubergi Zwölfer, 1927, a microsporidium originally isolated from the midgut epithelium of Nygmia phaeorrhoea Don (Euproctis chrysorrhoea L.) and Porthetria dispar L., and subsequently reported in several other insects including the spruce budworm, Choristoneura fumiferana (the host used in this investigation), does not belong in the genus Pleistophora Gurley, 1893. Pleistophora schubergi lacks the major features that are characteristic of Pleistophora typicalis, the type species of this genus. A comparison of ultrastructural observations reported for the type species of the genus Pleistophora, P. typicalis, and our observations of P. schubergi revealed significant differences. A thick (0.5 μm) amorphous coat, derived from parasite secretions and deposited external to the parasite plasmalemma, surrounds all developmental stages in P. typicalis. Double membranes, derived from host rough endoplasmic reticulum cisternae encircle the parasite plasmalemma of all developmental stages in P. schubergi. The sporophorous vesicle encases the spores in P. typicalis, and originates from the parasite-secreted coat that is present around meronts. In P. schubergi, the host endoplasmic reticulum cisternae form the envelope that surrounds the meronts. Moreover, the sporophorous vesicle envelope in P. typicalis persists around groups of spores, while in P. schubergi this envelope breaks easily to release the spores in the host cytoplasm. By comparing the characteristics of the microsporidium found in the spruce budworm with those of the recently created polysporous genera that sporulate within a vesicle, we found that P. schubergi does belong in the new genus Endoreticulatus Brooks et al. 1988, and consequently rename it Endoreticulatus schubergi (Zwölfer, 1927) n. comb.     

A survey of unresolved problems in life cycle assessment

Background, aims, and scope  Life cycle assessment (LCA) stands as the pre-eminent tool for estimating environmental effects caused by products and processes from ‘cradle to grave’ or ‘cradle to cradle.’ It exists in multiple forms, claims a growing list of practitioners and remains a focus of continuing research. Despite its popularity and codification by organizations such as the International Organization for Standardization and the Society of Environmental Toxicology and Chemistry, life cycle assessment is a tool in need of improvement. Multiple authors have written about its individual problems, but a unified treatment of the subject is lacking. The following literature survey gathers and explains issues, problems and problematic decisions currently limiting LCA’s impact assessment and interpretation phases. Main features  The review identifies 15 major problem areas and organizes them by the LCA phases in which each appears. This part of the review focuses on the latter eight problems. It is meant as a concise summary for practitioners interested in methodological limitations which might degrade the accuracy of their assessments. For new researchers, it provides an overview of pertinent problem areas toward which they might wish to direct their research efforts. Having identified and discussed LCA’s major problems, closing sections highlight the most critical problems and briefly propose research agendas meant to improve them. Results and discussion  Multiple problems occur in each of LCA’s four phases and reduce the accuracy of this tool. Considering problem severity and the adequacy of current solutions, six of the 15 discussed problems are of paramount importance. In LCA’s latter two phases, spatial variation and local environmental uniqueness are critical problems requiring particular attention. Data availability and quality are identified as critical problems affecting all four phases. Conclusions and recommendations  Observing that significant efforts by multiple researchers have not resulted in a single, agreed upon approach for the first three critical problems, development of LCA archetypes for functional unit definition, boundary selection and allocation is proposed. Further development of spatially explicit, dynamic modeling is recommended to ameliorate the problems of spatial variation and local environmental uniqueness. Finally, this paper echoes calls for peer-reviewed, standardized LCA inventory and impact databases, and it suggests the development of model bases. Both of these efforts would help alleviate persistent problems with data availability and quality.

Life cycle of Craspedacusta sowerbyi xinyangensis

To explore the life cycle of Craspedacusta,the authors collected male and female specimens of the Craspedacusta sowerbyi xinyangensis in a small fire-fighting pond in Ningbo,Zhejiang Province in July,2005 and 2006.The development of C.sowerbyi xinyangensis was studied from zygote to medusa by means of light microscopy and digital camera.The zygotes of C.sowerbyi xinyangensis are globular and smooth(90-105 μm diameter)and have an equal,total cleavage to the two-cell stage 15 min after fertilization.The embry...     

An Ultrastructural Study of Vairimorpha necatrix (Microspora, Microsporida) with Particular Reference to Episporontal Inclusions During Octosporogony

ABSTRACT. The life cycle of Vairimorpha necatrix was studied by electron microscopy. Disporous development has two distinct stages: 1) diplokaryotic meronts which are actively mitotic, and 2) diplokaryotic sporonts which are distinguished by reduced ribosome density and a thickened plasmalemma. After final division of the sporont, sporoblasts form spores which are ovocylindrical and measure 4.4 ± 0.08 × 2.3 ± 0.05 μ m (mean ± SE). Octosporous development results in eight haploid spores being formed in a sporophorous vesicle. The uninucleate octospores were smaller than the binucleate dispores and the exospore was thicker but less crenulate in outline. Early in octosporogony, tubules are produced from the sporont plasmalemma and electron-dense material accumulates in the episporontal space. The latter may be amorphous, vesiculated, or vacuolated in appearance and in later stages may take a stacked, lamellar form. At sporoblast formation, exospore material coats the plasmalemma and attached tubules; all inclusions in the episporontal space gradually disappear as spores are formed. These secretory products may have application to taxonomic distinction at the species level.     

Developmental Stages of Trypanosoma (Megatrypanum) freitasi Rego, Magalhaes & Siqueira, 1957 in the Opossum Didelphis marsupialis (Marsupialia, Didelphidae)

Trypanosoma (Megatrypanum) freitasi, a parasite of marsupials of the genus Didelphis, has been found to undergo in the lumen of the scent (anal) glands of its vertebrate host, a cycle such as usually occurs in the intestinal tract of the insect vectors of trypanosomatids and similar to what has been reported for Trypanosoma (Schizotrypanum) cruzi. The invertebrate host of Trypanosoma freitasi is still unknown. Developmental stages of the trypanosome in its mammalian host, especially the dividing epimastigotes, multinucleate plasmodial forms and rosettes found in the lumen of the scent glands of a naturally infected Didelphis marsupialis are described and illustrated.     

Phylogenetic Position of Amblyospora Hazard & Oldacre (Microspora: Amblyosporidae) Based on Small Subunit rRNA Data and Its Implication for the Evolution of the Microsporidia

ABSTRACT. Sequences of the small subunit rRNA genes of Amblyospora californica and an Amblyospora sp. from Culex salinarius were determined. These sequences were compared phylogenetically with 16 other microsporidia. The results suggest Amblyospora forms a sister taxon to the rest of the microsporidia examined. The basal position of Amblyospora is discussed with respect to the evolution of microsporidian life cycles. These sequences represent the longest microsporidian small subunit rRNA genes sequenced to date, 1,359 and 1,358 bp, respectively. Structural features and GC content (49% for both) are comparable to those of other microsporidia which have been sequenced.     

A parthenogenetic life cycle in a population of Canthocamptus Staphylinus (Copepoda,Harpacticoida)

The harpacticoid copepod Canthocamptus staphylinus (Jurine) was shown to reproduce parthenogenetically in an oligotrophic Finnish lake. The population was univoltine with peaks of egg production in winter and early spring. Young from both peaks became adults in spring and aestivated as cysts. Laboratory experiments suggested that either high temperature (12 °C or more) or long days will inhibit egg production, but that both factors together are needed to induce encystment. Embryonic survival was low, on the average only 60%. The population was limited by low food levels in winter, and it is suggested that food shortage prevents the species from colonizing the profundal zone of oligotrophic lakes.     

Acaricidal and biological activities of Titanium dioxide and Zinc oxide nanoparticles on the two-spotted spider mite,Tetranychus urticae Koch (Acari: Tetranychidae) and their side effects on the predatory mite,Neoseiulus californicus (Acari: Phytoseiidae)

The excessive application of pesticides raises environmental pollution levels, necessitating the need to identify alternative substances that do not cause ecological damage. In this context, the toxicity and residual efficacy of titanium dioxide (TiO₂) and zinc oxide (ZnO) nanoparticles (NPs) compared to abamectin against adult females of T. urticae was evaluated under laboratory and greenhouse conditions. In addition, the effects of tested NPs on the biological parameters of T. urticae as well as their side effects on the predatory mite, Neoseiulus californicus were examined. In laboratory bioassays, LC₅₀ values of TiO₂ and ZnO NPs were 5.82 and 7.09 mg L^–1, respectively, compared to 4.90 mg L^–1 in abamectin 72 hr post-treatment. TiO₂ and ZnO NPs had a prolongation effect on both the developmental and reproductive durations with mean life spans of 33.18 ± 0.72 days and 30.53 ± 0.82 days in the case of TiO₂ and ZnO NPs, respectively, compared to 24.65 ± 0.53 days in the normal case. Treated T. urticae females produced lesser fecundities (10–22 eggs less than the normal mean) and decreased hatchability rates. The highest mortality percentages in T. urticae populations were 92.4 % and 90.0 % after 24 h of spraying with TiO₂ and ZnO NPs, respectively, compared to 98.4 % in abamectin. In contrast, tested NPs demonstrated less toxicity in N. californicus populations with no phytotoxicity on treated leaves. This study is the first in Egypt to investigate the NPs control of T. urticae mites infesting cucumber plants and the effects on their biology and natural enemies.     

桔粉虱种群动态及杀虫剂对其影响

本文报道了长兴岛桔粉虱生活史及习性、自然种群生命表资料以及大田种群动态,并研究了杀虫剂对桔粉虱的影响。桔粉虱在长兴岛一年发生3代,以Ⅳ龄若虫越冬。各虫态中卵及Ⅳ龄若虫死亡率最高,Ⅱ龄若虫较低,每年3代中以第2代死亡率最高。桔粉虱存活率曲线属威布尔模型的第Ⅲ型。大田种群动态资料以种群年龄结构为特征反映了粉虱的田间数量消长及杀虫剂对其影响。对防护林女贞树上的粉虱种群动态进行分析,并将粉虱作为江原钝绥螨的交替饲料进行了讨论。     

Ochropsora staphyleae,a new rust pathogen of Japanese bladdernut,found in central Japan

Japanese bladdernut shrub, Staphylea bumalda (Staphyleaceae), was found infected by a fungus in Prefectures of Ibaraki and Tochigi, central Japan. The fungus produced telia beneath the host epidermis and basidiospores on metabasidia emerging from the sori on the abaxial leaf surface. Probasidia were single-celled, sessile, short-cylindrical, thin-walled, and laterally free. A four-celled metabasidium arose from a probasidium by apical elongation. Apparent biotrophic nature and the basidium morphology of the Staphylea fungus suggested its taxonomic affinity to the rust genus Ochropsora. Molecular phylogenetic analyses of D1/D2 region of LSU rDNA showed that two collections of the fungus were grouped with Ochropsora ariae (type species of the genus) and O. nambuana but formed an independent clade. The fungus under consideration was, therefore, classified in Ochropsora, and a new name, O. staphyleae, was proposed for it.     

Cell cycle and behaviour in Euplotes crassus: an attempt at describing the biological relationship between its cellular and organismic natures

The two-faced nature of protozoa allowed us to study the relationship between cell cycle and behaviour in Euplotes crassus; the former represents one of the most typical cellular traits, the latter is one of the most significant characteristics of an organism. Dividing cells of E. crassus were isolated on a slide and recorded for 11 h: the classic ethographic parameters were calculated every 60 min. The percentage of mobile cells went from 0-100% in the first 2.5 h. This value was maintained for 6.5 h, but from 9 h the value began to drop, reaching 0% at 11 h. The relative frequency of leftward arcs was very high in the first hour, the radius and length of the arcs increased from 1-7 h; velocity showed a similar trend, peaking at 7 h. All our results showed that the behaviour of this ciliate is heavily affected by its cell-division cycle.     

Phragmidium satoanum,a new rust pathogen of Rosa hirtula in Japan

The causal fungus of a rust disease of Rosa hirtula, endemic to mountainous areas of Fuji-Hakone-Izu National Park, Japan, was thought to be a common species Phragmidium rosae-multiflorae. Continued field observations, morphological examination, and experimental inoculations proved that the fungus produced laterally three-angled aeciospores and urediniospores together with multi-cellular teliospores on the same R. hirtula trees. These morphological features were different from those of P. rosae-multiflorae. The fungus parasitized only R. hirtula. Experimental inoculations and field observations did not prove that R. banksiae, R. laevigata, and R. multiflora supported infection and sporulation of the fungus. Under the field observations, R. multiflora, the most common host of P. rosae-multiflorae, was not proven to harbor the R. hirtula fungus. Therefore, the fungus was concluded to be a species distinct from P. rosae-multiflorae; and a new name, P. satoanum, was proposed for it.     

Ecological and morphological characteristics of Ephelota gemmipara (Ciliophora,Suctoria), epibiontic on Eudendrium racemosum (Cnidaria,Hydrozoa) from the Adriatic Sea

The relationship between the suctorian Ephelota gemmipara and the large hydroid Eudendrium racemosum from the North Adriatic Sea has been studied over its full annual cycle. Ephelota gemmipara settles on the perisarc of the hydroid, usually close to the hydranths in order to exploit the hydroid's food discharges. The life cycle of E. gemmipara is influenced by temperature variations and by its relationship with the host. The hydroid shows an active phase in the summer, and it gets through the adverse winter season forming resting stages. In April, when temperature increases, the hydroid starts its active phase and it is colonized by suctorians. From May to September the suctorians produce multiple buds (swarmers) that detach from the parental cells to settle on an Eudendrium colony. The abundance of the suctorian peaks in September, with more than 1.2 million ind. m^?2. Their proliferation coincides with the maximal abundance of their host and the highest water temperatures. On the contrary, sexual reproduction and the encystment occur when the temperature and the abundance of E. racemosum decrease. Lastly, we also report the presence of symbionts such as bacteria and the parasitic protozoans Tachyblaston ephelotensis and Enigmocoma acinetarum.     

Impact assessment for LCAs involving agricultural production

LCA has been developed primarily for industrial production systems. Application to agricultural systems requires systematic application of existing methodology and new methodological developments. Conventional approaches can obscure potential options for improving the environmental performance of systems involving agricultural production due to use of restricted system boundaries, incomplete assessment of impacts, and exclusion of ancillaries from the analysis. For use of nutrients such as phosphorus, it is proposed that Impact Assessment should be based on the quantity dispersed after use rather than on the input to the productive system. Eventually, the impacts associated with depletion should be based on technological or thermodynamic assessment of concentration for reuse, but this approach requires further theoretical development.