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PubMed1984

[Life cycle of Leranthropus kroyeri Van Beneden 1851, hematophagous branchial copepod of the sea bass Dicentrarchus labrax (Linné, 1758) in wild and experimental populations].

The life cycle of Lernanthropus kroyeri Van Beneden, 1851, copepod (Siphonostomatoida) parasite of Dicentrarchus labrax is described. The cycle comprises two nauplii, one infective copepodid, four fixed copepodids and one preadult. All the attached stages are caracterised by the lack of the frontal filament. This is the first description of a life cycle lacking a chalimus for Siphonostomatoida Copepods parasitic on fish.

Animals↗

PubMed2005

[The history of the exploration of the Diphyllobothrium latum life cycle].

Diphyllobothrium latum typically occur in the subarctic and temperature zones of the Eurasian Continent, however it is also observed in the Arctic Region and Australia. Raw fish meat and raw shell-fish containing plerocercoids is the main source of human infections. Humans are the principial final host of D. latum. Under primitive conditions human excrements with immature tapeworm eggs are deposited anywhere. After embrionic development which occurs in the water, the eggs are transformed into coracidia. Two intermediate hosts (cyclop and fish) are needed for further development. The free-swimming coracidium must enter the stomach of different species of Copepoda. After contact with the intestinal juice of the cyclop, the coracidium loses its ciliated envelope and the hooks become mobile. The metamorphosis of the oncosphere to the procercoid occurs. The discovery of the procercoid done by Janicki and Rosen in 1917 implied that the missing link in the cycle of the broad tapeworm had been found. The copepod including the procercoid is consumed by the second intermediate host. The larvae escape from the digestive tract of the fish and are transformed into a plerocercoid. The plerocercoids develop slowly in the fish, and they must reach a certain degree of maturity to be capable of infecting the final host. Today the life cycle of the tapeworm is well recognized and well illustrated in parasitological textbooks and websites. In this paper the history of the exploration of the D. latum life cycle is described. Additionally the main scientific researches carried out on life stages of the broad tapeworm have been reviewed.

Animals↗

PubMed1999

Growth and development in Arabidopsis thaliana through an entire life cycle under simulated microgravity conditions on a clinostat.

The effects of simulated microgravity conditions produced by a horizontal clinostat on the entire life cycle of Arabidopsis thaliana ecotype Columbia and Landsberg erecta were studied. Horizontal clinorotation affected little germination of seeds, growth and development of rosette leaves and roots during early vegetative growth stage, and the onset of the bolting of inflorescence axis and flower formation in reproductive growth stage, although it suppressed elongation of inflorescence axes. The clinorotation substantially reduced the numbers of siliques and seeds in Landsberg erecta, and completely inhibited seed production in Columbia. Seeds produced in Landsberg erecta on the clinostat were capable of germinating and developing rosette leaves normally on the ground. On the other hand, growth of pin formed mutant (pin/pin) of Arabidopsis ecotype Enkheim, which has a unique structure of inflorescence axis with no flower and extremely low levels of auxin polar transport activity, was inhibited and the seedlings frequently died during vegetative stage on the clinostat. Seed formation and inflorescence growth of the seedlings with normal shape (pin/+ or +/+) were also suppressed on the clinostat. These results suggest that the growth and development of Arabidopsis, especially in reproductive growth stage, is suppressed under simulated microgravity conditions on a clinostat. To complete the life cycle probably seems to be quite difficult, although it is possible in some ecotypes.

Arabidopsis↗

PubMed1996

Chronic illness and the family life-cycle.

Chronic illness is currently the outstanding health issue in the United States. It creates increased family stress, requires constant adaptation by the family members and poses a challenge to nurses to better understand and meet the needs of the family as well as the individual. This paper presents a psychosocial typology of chronic illness and discusses the importance of time phasing of the chronic illness. A conceptual framework for analysing the interaction of chronic illness with family and individual life-cycles is outlined. Knowledge of life-cycle stressors is essential for nurses to better delineate the relationship between the vertical and horizontal life stressors which affect the family system.

Adaptation, Psychological↗

PubMed1983

Life cycle efficiency of beef production: II. Relationship of cow efficiency ratios to traits of the dam and progeny weaned.

Several measures of life cycle cow efficiency were calculated using weights and individual feed consumptions recorded on 160 dams of beef, dairy and beef X dairy breeding and their progeny. Ratios of output to input were used to estimate efficiency, where outputs included weaning weights of progeny plus salvage value of the dam and inputs included creep feed consumed by progeny plus feed consumed by the dam over her entire lifetime. In one approach to estimating efficiency, inputs and outputs were weighted by probabilities that were a function of the cow herd age distribution and percentage calf crop in a theoretical herd. The second approach to estimating cow efficiency involved dividing the sum of the weights by the sum of the feed consumption values, with all pieces of information being given equal weighting. Relationships among efficiency estimates and various traits of dams and progeny were examined. Weights, heights, and weight:height ratios of dams at 240 d of age were not correlated significantly with subsequent efficiency of calf production, indicating that indirect selection for lifetime cow efficiency at an early age based on these traits would be ineffective. However, females exhibiting more efficient weight gains from 240 d to first calving tended to become more efficient dams. Correlations of efficiency with weight of dam at calving and at weaning were negative and generally highly significant. Height at withers was negatively related to efficiency. Ratio of weight to height indicated that fatter dams generally were less efficient. The effect of milk production on efficiency depended upon the breed combinations involved. Dams calving for the first time at an early age and continuing to calve at short intervals were superior in efficiency. Weaning rate was closely related to life cycle efficiency. Large negative correlations between efficiency and feed consumption of dams were observed, while correlations of efficiency with progeny weights and feed consumptions in individual parities tended to be positive though nonsignificant. However, correlations of efficiency with accumulative progeny weights and feed consumptions generally were significant.

Animals↗

PubMed2002

Sm14 gene expression in different stages of the Schistosoma mansoni life cycle and immunolocalization of the Sm14 protein within the adult worm.

Sm14 is a 14-kDa vaccine candidate antigen from Schistosoma mansoni that seems to be involved in cytoplasmic trafficking of fatty acids. Although schistosomes have a high requirement for lipids, they are not able to synthesize fatty acids and sterols de novo. Thus, they must acquire host lipids. In order to determine whether Sm14 is present in different stages of the life cycle of the parasite, we performed RT-PCR. Sm14 mRNA was identified in all stages of the life cycle studied, mainly schistosomulum, adult worm and egg. Additionally, we used a rabbit anti-Sm14 polyclonal antibody in an indirect immunofluorescence assay to localize Sm14 in adult worm sections. The basal lamella of the tegument and the gut epithelium were strongly labeled. These tissues have a high flow of and demand for lipids, a finding that supports the putative role of Sm14 as an intracellular transporter of fatty acids from host cells.

Animals↗

PubMed2004

Description and proposed life cycle of Maritrema novaezealandensis n. sp. (Microphallidae) parasitic in red-billed gulls, Larus novaehollandiae scopulinus, from Otago Harbor, South Island, New Zealand.

Maritrema novaezealandensis n. sp. is described from Otago Harbor, South Island, New Zealand, on the basis of adult specimens collected from the Red-billed gull, Larus novaehollandiae scopulinus, and excysted metacercariae obtained from crabs. It belongs to the "eroliae group" and differs from other related species mainly in the shape, size, and patterns of distributions of the spines on the cirrus, the shape of the metraterm, the presence of an unlobed ovary, and the complete ring of the vitelline follicles. Based on morphometric features of metacercariae and adult specimens, the trophic relationships among invertebrate and vertebrate hosts, experimental infections, and previous reports of species of Maritrema with similar transmission patterns, the life cycle of M. novaezealandensis n. sp. is described. A 3-host life cycle is proposed for this parasite. The first intermediate host is the mud snail, Zeacumantus subcarinatus, in which the cercarial stage is produced in sporocysts located within the gonad of the snail. At least 3 crab species (Hemigrapsus crenulatus, Macrophtalmus hirtipes, and Halicarcinus whitei) and several species of amphipods act as second intermediate hosts, with metacercariae encysted in the body cavity of the crustacean host. Finally, the definitive host, the gull, L. n. scopulinus, harbors the adult worms in its intestine.

Amphipoda↗

PubMed2000

Vitellocytes and vitellogenesis in cestodes in relation to embryonic development, egg production and life cycle.

Vitellocytes have two important functions in cestode embryogenesis: (1) formation of hard egg-shell (e.g. Pseudophyllidea) or a delicate capsule (e.g. Cyclophyllidea), and (2) supplying nutritive reserves for the developing embryos. During evolution any of these two functions can be reduced or intensified in different taxa depending on the type of their embryonic development, degree of ovoviviparity and life cycles. Within the Cestoda, there are three monozoic taxa with only one set of genital organs: Amphilinidea, Gyrocotylidea and Caryophyllidea. In these monozoic taxa and some polyzoic groups with well developed vitellaria (e.g. Pseudophyllidea, Trypanorhyncha) a single oocyte [=germocyte] and a large number of vitellocytes (up to 30) are enclosed within a thick, hardened egg-shell, forming a type of eggs typical for the basic pattern of Neodermata. Only one type of egg-shell enclosures, the so-called 'heterogeneous shell-globule vesicle' is common for the above mentioned cestode taxa. Each membrane-bounded vesicle of mature vitellocytes contains numerous electron-dense shell globules embedded in a translucent matrix. In free-living Neoophora and Monogenea there are two types of vesicles with dense granules; the second is considered to be proteinaceous reserve material. Within the Cestoda, the numbers of vitellocytes per germocyte are reduced in those taxa forming eggs of the 'Cyclophyllidean-type' (e.g. Cyclophyllidea, Tetraphyllidea, Pseudophyllidea). This is particularly evident in Cyclophyllidea; for example, in vitellocytes of Hymenolepis diminuta (Hymenolepididae) there are numerous vitelline granules of homogeneously electron-dense material; in Catenotaenia pusilla (Catenotaeniidae) there are three large, homogenous vitelline vesicles, while in Inermicapsifer madagascariensis (Anoplocephalidae) there is only one large vitelline vesicle, containing homogeneously electron-dense material, which occupies most of the vitelline cell volume. In this respect the Tetraphyllidea and Proteocephalidea, in forming eggs that lack a hard egg-shell, hold an intermediate position. A comparison of interrelationships which exist among types of vitellocytes, vitellogenesis, types of embryonic development, ovoviviparity and life cycles indicates parallelisms and analogies in adaptation to the parasitic way of life in different groups of cestodes. Knowledge on cestode vitellogenesis may also have an important applied aspect. Vitellocytes, due to their high metabolic rate, represent a very sensitive target for analysing effect of anthelminthic drugs upon the egg formation (ovicidal effects); rapid degeneration of vitellocytes is usually accompanied by a cessation of egg production.

Animals↗

PubMed2002

A hereditary disorder in the family and the family life cycle: Huntington disease as a paradigm.

The implications of predictive DNA-testing for Huntington's Disease (HD) for the transitions in the family life cycle are described. HD is a hereditary disorder leading to personality changes, uncontrollable movements, cognitive impairment, and ultimately death in mostly adults. People at risk have the possibility to detect whether or not they carry the disease provoking-gene, but no treatment is available. In this article, we will highlight the complex implications of pre-symptomatic testing by describing six different cases, interpreted by following the theoretical framework of Carter and McGoldrick (see pp. 684). HD interferes strongly with the "normal" transitions in the life cycle. It is not so much the test result itself that may be disrupting, but the changed expectations and possibilities for the future. As a family disease, HD forces its members to cope, one way or another, with disturbing events and untimely deaths. Some families are able to make some transitions, while becoming blocked at other transition points; this may differ between families. Being able to cope with HD in the family for a certain time does not necessarily imply that problems will never occur. Because any family member may eventually need help, it is important to then help the family discover what hinders them from making the transition to the next life stage, and to resolve these issues so that they can move on.

Adaptation, Psychological↗

PubMed1977

Nuclear DNA content and chromosome numbers throughout the life cycle of the Colonia strain of the myxomycete, Physarum polycephalum.

Nuclear DNA content and ploidy have been determined at different stages of the life cycle of the Colonia strain of the myxomycete Physarum polycephalum. Analyses at the plasmodial stage showed that (a) Burton and Fuelgen DNA analyses agreed within 15% with strains which ranged from 0-6 to 3-6 pg of DNA per nucleus; (b) S-phase in Colonia is during the early part of interphase as in the Wisconsin strain; (c) in heterothallic and heterothallic x Colonia crossed strains there are 1-0-1-2 pg of DNA and 70 chromosomes per nucleus and in Colonia 0-6 pg of DNA and 40 chromosomes. Germinating spores of all strains contained one population of cells with about 0-5 pg of DNA and 40 chromosomes and another of larger cells with up to 2-5 pg of DNA and 200 chromosomes. The polyploid nuclei comprised 2-20% of the total in heterothallic strains, 2-65% in heterothallic x Colonia crosses and 25-75% in Colonia. A method was devised for making chromosome spreads of amoebae grown on bacterial lawns. Cells were first exposed to dilute formaldehyde at 26 degrees C for 30 min, then spread on slides with hot lactic acid and strained. Such spreads of CLd (Colonia) and RSD4 (heterothallic) amoebae both contained about 40 chromosomes. The data are consistent with the view that Colonia is haploid throughout its life cycle and that chromosome number is neither halved during sporulation nor doubled during plasmoidal formation. However, the possibility exists that an alternance of ploidy occurs by way of the few diploid nuclei present in the plasmodium.

Cell Division↗

PubMed2004

A Plasmodium berghei reference line that constitutively expresses GFP at a high level throughout the complete life cycle.

Green fluorescent protein (GFP) is a well-established reporter protein for the examination of biological processes. This report describes a recombinant Plasmodium berghei, PbGFPCON, that constitutively expresses GFP in a growth responsive manner in its cytoplasm from a transgene that is integrated into the genome and controlled by the strong promoter from a P. berghei elongation factor-1alpha gene. All life cycle forms of PbGFPCON except for male gametes can be easily visualized by fluorescent microscopy. PbGFPCON showed similar growth characteristics to wild type P. berghei parasites throughout the whole life cycle and can therefore be used as a reference line for future investigations of parasite-host cell interactions. The principle of automated fluorescence-based counting and sorting of live parasites from host cell backgrounds and different parasite forms from complex mixtures such as asynchronous blood stages is established. PbGFPCON allows the visualization and investigation of live parasite stages that are difficult and labor-intensive to observe, such as the liver and mosquito stages. PbGFPCON can be employed to establish the phenotype of independent mutant parasites. With the recent development of a second, independent selectable marker in P. berghei, PbGFPCON is a useful tool to investigate the effect of further genetic modifications on host-parasite interactions.

Animals↗

PubMed2003

Growth responses of an estuarine fish exposed to mixed trace elements in sediments over a full life cycle.

Hatchling Cyprinodon variegatus were raised in the presence or absence of sediments contaminated with mixed trace elements to examine lethal and sublethal bioenergetic effects (metabolic rate, lipid storage, growth, reproduction) over a full life cycle (>1 year). Contaminated sediments were derived from a site receiving coal combustion residues (CCR) and were elevated in numerous trace elements including Al, As, Ba, Cd, Cu, Se, and V. Exposures were conducted at two levels of salinity (5 and 36 ppt) to examine the potential interaction of this variable with contaminants. Salinity had no effect on responses measured. Over the course of the study, fish exposed to contaminated sediment accumulated several CCR-related trace elements, including As, Cd, Se, and V. There were no differences in fish survival for contaminated sediment treatments and uncontaminated sediment treatments, nor were there differences in metabolic expenditures. However, growth, male condition factor, and storage lipid content in females were reduced due to contaminant exposure. No significant effects on fecundity or the proportion of females that were gravid at the end of the study were observed, yet females raised under control conditions produced 12% larger eggs than did females raised on contaminated sediments. During the presumably most-sensitive early life stages, individuals were not noticeably affected by contaminants, but rather the effects of exposure became apparent later in life. Because many species inhabit contaminated areas for long periods of time, often encompassing the entire life cycle, exposures focused only on specific life stages may substantially underestimate the overall responses elicited by individuals.

Animals↗

PubMed1979

Studies on the life cycle of Asymphylodora tincae (Modeer, 1790) (Trematoda: Monorchiidae) in a small lake near Amsterdam. Part 1. The morphology of various stages.

Aspects of the life cycle of Asymphylodora tincae have been studied in a small lake near Amsterdam. Bithynia tentaculata, being the only snail species that was very numerous in the lake, was the first as well as the main second intermediate host; adult trematodes were found exclusively in the tench, Tinca tinca. A small part of the cercariae that penetrate into B. tentaculata was able to develop into progenetic specimens. A morphological description is given of the following stages of A. tincae: adult, egg, redia, cercariaeum, metacercaria and progenetic stage. The cercariaeum is identified as Cercariaeum paludinae impurae De Filippi, 1854. It is concluded that A. tincae is a species, capable of large variation regarding both morphological structure (e.g. body spination, size) and life cycle.

Animals↗

PubMed2005

The life cycle and pathogenicity of coccicium Eimeria nocens (Kotlán, 1933) in domestic goslings.

Twenty-four 10-day-old, artificially reared, coccidia-free goslings (Anser cygnoides var. domestica) were inoculated orally with 1.0x10(5)-1.0x10(6) sporulated oocysts of Eimeria nocens, and killed at intervals from 30 to 336 hr postinoculation (PI). Parts of the visceral organs, including intestines, kidney, liver, gallbladder, and spleen from inoculated goslings, were fixed and sectioned. The life cycle of E. nocens and histologic changes during infection were examined microscopically. The results showed that at least 3 generations of meronts developed in the endogenous stage of the life cycle of E. nocens. Two types of meronts were found. The first completed maturation at 54 to 78 hr PI. These meronts were the first generation, with each forming about 12 merozoites. The second completed maturation at 102 to 240 hr PI. These meronts were the second or third generations, with each meront forming about 24 merozoites. Development of gamonts began at about 198 hr after infection. The prepatent period was 9 days and discharge of oocysts continued for 4 days. Sporulation of oocysts occurred in 60-72 hr at 25 C. Eimeria nocens invaded the posterior jejunum, ileum, caecum, rectum, and cloaca. Developmental stages were localized within the epithelial cells of villi and crypts, and in lamina propria. Marked histological changes, including desquamation and necrosis of intestinal epithelium, submucosal edema, hemorrhages, infiltration of inflammatory cells, and villous atrophy, were seen during the periods of late merogony, gamogony, and oocyst shedding. They were most pronounced in the ileum and the regions nearby. The infected goslings showed severe diarrhea, bloody feces, anorexia, emaciation, and even death, suggesting that E. nocens is highly pathogenic for goslings.

Animals↗

PubMedDate not supplied

[The life cycle of Plagiorchis neomidis Brendow, 1970, digenean parasite of Neomys fodiens in the Pyrénées. Chronobiology of cercarial emergence (author's transl)].

The first host in the life cycle of Plagiorchis neomidis in the Pyrenees is the Mollusc Radix limosa var, glacialis. The cercariae encyst in the aquatic larvae of the Insect Sialis lutaria (Megaloptera). The adult parasite is found in the rectum of Neomys fodiens. The chetotaxy and the rhythm of cercarial emergence are described in detail as is the development of the metacercaria in its second intermediate host. Comparison of the life cycle of P. neomidis in the Pyrenees with that described in Germany demonstrates differences in the biology at both larval and adult stage.

Animals↗

PubMed2003

Evaluating uncertainty in environmental life-cycle assessment. A case study comparing two insulation options for a Dutch one-family dwelling.

The evaluation of uncertainty is relatively new in environmental life-cycle assessment (LCA). It provides useful information to assess the reliability of LCA-based decisions and to guide future research toward reducing uncertainty. Most uncertainty studies in LCA quantify only one type of uncertainty, i.e., uncertainty due to input data (parameter uncertainty). However, LCA outcomes can also be uncertain due to normative choices (scenario uncertainty) and the mathematical models involved (model uncertainty). The present paper outlines a new methodology that quantifies parameter, scenario, and model uncertainty simultaneously in environmental life-cycle assessment. The procedure is illustrated in a case study that compares two insulation options for a Dutch one-family dwelling. Parameter uncertainty was quantified by means of Monte Carlo simulation. Scenario and model uncertainty were quantified by resampling different decision scenarios and model formulations, respectively. Although scenario and model uncertainty were not quantified comprehensively, the results indicate that both types of uncertainty influence the case study outcomes. This stresses the importance of quantifying parameter, scenario, and model uncertainty simultaneously. The two insulation options studied were found to have significantly different impact scores for global warming, stratospheric ozone depletion, and eutrophication. The thickest insulation option has the lowest impact on global warming and eutrophication, and the highest impact on stratospheric ozone depletion.

Air Pollution, Indoor↗

PubMed2004

Life cycle assessment part 2: current impact assessment practice.

Providing our society with goods and services contributes to a wide range of environmental impacts. Waste generation, emissions and the consumption of resources occur at many stages in a product's life cycle-from raw material extraction, energy acquisition, production and manufacturing, use, reuse, recycling, through to ultimate disposal. These all contribute to impacts such as climate change, stratospheric ozone depletion, photooxidant formation (smog), eutrophication, acidification, toxicological stress on human health and ecosystems, the depletion of resources and noise-among others. The need exists to address these product-related contributions more holistically and in an integrated manner, providing complimentary insights to those of regulatory/process-oriented methodologies. A previous article (Part 1, Rebitzer et al., 2004) outlined how to define and model a product's life cycle in current practice, as well as the methods and tools that are available for compiling the associated waste, emissions and resource consumption data into a life cycle inventory. This article highlights how practitioners and researchers from many domains have come together to provide indicators for the different impacts attributable to products in the life cycle impact assessment (LCIA) phase of life cycle assessment (LCA).

Climate↗

PubMed2006

Life-cycle and growth-phase-dependent regulation of the ubiquitin genes of Trypanosoma cruzi.

BACKGROUND: Trypanosoma cruzi, the causative agent of Chagas disease, exhibits a complex life cycle that is accompanied by the stage-specific gene expression. At the molecular level, very little is known about gene regulation in trypanosomes. Complex gene organizations coupled with polycistronic transcription units make the analysis of regulated gene expression difficult in trypanosomes. The ubiquitin genes of T. cruzi are a good example of this complexity. They are organized as a single cluster containing five ubiquitin fusion (FUS) and five polyubiquitin (PUB) genes that are polycistronically transcribed but expressed differently in response to developmental and environmental changes. METHODS: Gene replacements were used to study FUS and PUB gene expression at different stages of growth and at different points in the life cycle of T. cruzi. RESULTS: Based on the levels of reporter gene expression, it was determined that FUS1 expression was downregulated as the parasites approached stationary phase, whereas PUB12.5 polyubiquitin gene expression increased. Conversely, FUS1 expression increases when epimastigotes and amastigotes differentiate into trypomastigotes, whereas the expression of PUB12.5 decreases when epimastigotes differentiate into amastigotes and trypomastigotes. CONCLUSIONS: Although the level of CAT activity in logarithmic growing epimastigotes is six- to seven-fold higher when the gene was expressed from the FUS1 locus than when expressed from the PUB12.5 locus, the rate of transcription from the two loci was the same implying that post-transcriptional mechanisms play a dominant role in the regulation of gene expression.

Animals↗