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PubMed2004

Ten years after medaka fish mated and laid eggs in space and further preparation for the life-cycle experiment on ISS.

In the second International Microgravity Laboratory (IML-2/STS-65) mission in 1994, medaka fish (Oryzias latipes) performed their successful mating behavior in space for the first time among vertebrate animals. The eggs the fish laid in space developed normally, and hatched as fry (baby fish) in space. Those fry born in space had the same number of germ cells as the ground control fish, and these germ cells later developed to produce the offspring on the ground. Fry hatched in space did not exhibit any looping behavior regardless of their strain, visual acuity, etc. For fish, one of the most exciting experiments to be done abroad the International Space Station (ISS) is a realization of fish life cycles in microgravity. At present, fish are the most likely candidates to be the first vertebrate to live their life cycle in space. Research done in our laboratory for realizing the life-cycle experiment of medaka fish are also introduced.

Animals↗
PubMed2005

The life cycle of Henneguya nuesslini Schuberg & Schroder, 1905 (Myxozoa) involves a triactinomyxon-type actinospore.

The life cycle of the histozoic myxozoan parasite Henneguya nuesslini was investigated in two salmonid host species. Naive brown trout, Salmo trutta, and brook trout, Salvelinus fontinalis, were experimentally infected in two trials by triactinomyxon type actinospores from naturally infected Tubifex tubifex. In exposed common carp, Cyprinus carpio, no myxospore production was detected. The parasite formed cysts with mature myxospores in the connective tissue of the fish 102 days post-exposure. The morphology of both actinosporean and myxosporean stages was described by light microscopy and a 1417-bp fragment of the 18S rDNA gene was sequenced. Sequence analysis confirmed the absolute congruence of the two developmental stages and assisted in determining species identity. Host range, tissue specificity and myxospore measurements provided sufficiently distinctive features to confirm species validity and were thus crucial for identification. The triactinomyxon spores had 16 secondary germ cells, unique dimensions, a very opaque sporoplasm matrix and three conspicuously protruding, pyriform polar capsules. This is the first record of a Henneguya sp. life cycle with a triactinomyxon-type actinospore, which suggests a close relationship with the Myxobolus group and a polyphyletic origin of the genus Henneguya.

Animals↗
PubMed1987

The colonization and life-cycles of Musca lusoria, Musca xanthomelas and Musca nevilli, vectors of Parafilaria bovicola in South Africa.

Thriving, permanent colonies of Musca xanthomelas and later of Musca nevilli were successfully established. However, because of the low reproduction potential of Musca lusoria a small colony only was kept for a limited period until life-cycle studies were completed. Larvae were reared on fresh dung from cattle fed lucerne, while in general adults were fed 0.3% citrated ox-blood, whole milk powder, sugar crystals, fresh dung and water. M. nevilli could be colonized only when ox-liver was substituted for ox-blood. A comparison of the life-cycles of M. lusoria and M. xanthomelas under laboratory conditions at a constant temperature of approximately 27 degrees C, 60% R.H. and 24 h illumination revealed major differences between these 2 vector species. M. lusoria deposits single larvae at intervals of approximately 2 days and a female can produce up to 27 in her life-time. An M. xanthomelas female can lay up to 4 batches of eggs, with as many as 33 eggs per batch, at intervals of approximately 5 days. A single female can produce a maximum of 94 eggs. M. lusoria, however, showed survival advantages over M. xanthomelas in that its larvae reached the pupal stage at least a day sooner and its adults survived more than twice as long. The life-cycles of M. xanthomelas and M. nevilli were similar in the laboratory, except for adult dietary requirements. The mean number of mature oocytes in the ovaries of M. nevilli, however, was only 15.7 compared with 26.1 in M. xanthomelas.

Animals↗
PubMed2006

Life cycle assessment of wastewater treatment technologies treating petroleum process waters.

This paper describes the implementation of life cycle assessment to investigate the environmental impact of 20 technologies suitable for treating extensive volumes of water produced during the oil and gas extraction processes. Data on the physical and operational attributes of technologies under consideration were assembled and their life cycle environmental impacts estimated over 15 year time period. The results were then incorporated in a decision support system which allows identification and prioritisation of potential technology combinations capable of producing water for nine designated industrial and agricultural end uses. In total, more than 618 technology combinations were investigated for their environmental impacts. The identification and prioritisation of technologies were done on the basis of their environmental and technical performance. This analysis showed that dissolved air flotation, absorbents, dual media filtration and reverse osmosis technologies offer relatively low environmental impact parts of systems for cleaning such process waters. Furthermore, the environmental assessment combined within the decision support system has revealed potentially valuable indirect downstream "benefits" from effects such as evaporative losses from wetlands in terms of the overall environmental impact of a treatment system.

Extraction and Processing Industry↗
PubMed1995

Morphological and life-cycle aspects of the parasitic mite Trichosurolaelaps crassipes Womersley, 1956 of trichosurid possums.

All four life-cycle stages of the ubiquitous parasitic possum mite Trichosuroluelups crassipes Womersley, 1956 are illustrated. They comprise the ephemeral, quiescent and nonfeeding larva, an active feeding protonymph, an active feeding deutonymph and the adults. Morphological adaptations with viviparity allow the entire life-cycle of the mite to be completed on the host. The lack of a nidicolous egg or larva and the absence of a quiescent deutonymph implies transmission is via host-host contact.

Journal Article↗
PubMed2002

Genetic analysis of cis regulatory elements within the 5' region of the human papillomavirus type 31 upstream regulatory region during different stages of the viral life cycle.

The function of the 5' region of the upstream regulatory region (URR) in regulating E6/E7 expression in cancer-associated papillomaviruses has been largely uncharacterized. In this study we used linker-scanning mutational analysis to identify potential cis regulatory elements contained within a portion of the 5' region of the URR that are involved in regulating transcription of the E6/E7 promoter at different stages of the viral life cycle. The mutational analysis illustrated differences in the transcriptional utilization of specific regions of the URR depending on the stage of the viral life cycle. This study identified (i) viral cis elements that regulate transcription in the presence and absence of any viral gene products or viral DNA replication, (ii) the role of host tissue differentiation in viral transcriptional regulation, and (iii) cis regulatory regions that are effected by induction of the protein kinase C pathway. Our studies have provided an extensive map of functional elements in the 5' region (nuncleotides 7259 to 7510) of the human papillomavirus type 31 URR that are involved in the regulation of p99 promoter activity at different stages of the viral life cycle.

Cell Differentiation↗
PubMedDate not supplied

Life cycle, ultrastructure and molecular phylogeny of Hyalinocysta chapmani (Microsporidia: Thelohaniidae), a parasite of Culiseta melanura (Diptera: Culicidae) and Orthocyclops modestus (Copepoda: Cyclopidae).

The complete life cycle of the microsporidium Hyalinocysta chapmani is described from the primary mosquito host Culiseta melanura and the intermediate copepod host Orthocyclops modestus. Infections are initiated in larval C. melanura following the oral ingestion of uninucleate spores from infected copepods. Spores germinate within the lumen of the midgut and directly invade fat body tissue where all development occurs. Uninucleated schizonts undergo binary division (schizogony) followed by karyokinesis (nuclear division) to form diplokaryotic meronts. Merogony is by synchronous binary division. The onset of sporogony is characterized by the simultaneous secretion of a sporophorous vesicle and meiotic division of the diplokaryon resulting in the formation of eight ovoid meiospores enclosed within a sporophorous vesicle. Most infected larvae die during the fourth stadium and there is no evidence of a developmental sequence leading to vertical transmission. Hyalinocysta chapmani is horizontally transmitted to O. modestus via oral ingestion of meiospores. Infections become established within ovarian tissue of females and all parasite development is haplophasic. Uninucleate schizonts divide by binary division during an initial schizogonic cycle. Newly formed uninucleate cells produce a thin sporophorous vesicle and undergo repeated nuclear division during sporogony to produce a rosette-shaped, multinucleated sporogonial plasmodium with up to 18 nuclei. This is followed by cytoplasmic cleavage, sporogenesis, and disintegration of the sporophorous vesicle to form membrane-free uninucleate spores. Infected females eventually die and there is no egg development. The small subunit rDNA sequence of H. chapmani isolated from meiospores from C. melanura was identical to the small subunit rDNA sequence obtained from spores from O. modestus, corroborating the laboratory transmission studies and confirming the intermediary role of O. modestus in the life cycle. Phylogenetic analysis was conducted with closely related microsporidia from mosquitoes. Hyalinocysta chapmani did not cluster within described Amblyospora species and can be considered a sister group, warranting separate genus status.

Animals↗
PubMedDate not supplied

Transitions over the life cycle: a comparison of mothers and nonmothers.

Life histories of 50 mothers and 30 nonmothers, aged 60 to 95, were analyzed to identify differences between the two groups in developmental transitions over the life cycle. The overall developmental trajectories during adulthood did not differ significantly. Mothers, however, reported a greater number of transitions, and 30% reported they were adults before age 15 in contrast to 3% of nonmothers. Nonmothers experienced a more stable career trajectory. Mothers were from larger families. Never-married nonmothers were an only child, only daughter, or oldest daughter. The effect of historical and marital status on achievement of integrity during later years is suggested as somewhat more influential than motherhood status.

Aged↗
PubMed1981

Changes in family support networks over the life cycle of mentally retarded persons.

Utilization of personal and professional support networks by parents varies over the life cycle of their mentally retarded children. Data from a mail survey questionnaire, completed by 330 parents, were analyzed according to four stages in the life cycle: preschool (birth to 5 years old), elementary (6 to 12 years old), teenage (13 to 18 years old), and young adult (19 to 21 years old). In general, parents of younger children utilized more services and support networks and were more supportive of mainstreaming; parents of older children were less supported, more isolated, and more in need of expanded services.

Adolescent↗
PubMed1995

Hemagglutinin-neuraminidase of human parainfluenza 3: role of the neuraminidase in the viral life cycle.

The function of neuraminidase in the life cycle and pathogenesis of human parainfluenza virus type 3 (HPF3) was studied by analyzing a variant of HPF3 that has decreased neuraminidase enzymatic activity. The variant virus is more fusogenic than the wild-type virus during an acute infection. Cloning and sequencing of the fusion (F) and hemagglutinin-neuraminidase (HN) genes from this variant revealed a single amino acid change in the HN protein and no alterations in the F protein sequence. Analysis of the growth properties of this variant revealed a delay in release of virus particles into the supernatant. Addition of exogenous neuraminidase to the culture resulted in increased release of infections viral particles, suggesting that the viral neuraminidase is important for release of HPF3 from the infected cell surface. In addition, the behavior of the variant virus during high-multiplicity infection and in the presence of exogenous neuraminidase provided evidence that the neuraminidase of HPF3 determines the outcome of viral infection (cytopathic versus persistent) in cell culture.

Genetic Variation↗
PubMed1991

The life cycle of Echinochasmus bagulai (Trematoda: Echinostomatidae).

The life history of Echinochasmus bagulai, an echinostomatid trematode in birds, is reported and stages in the life cycle are described. Natural infections with cercariae, which are of the gymnocephalous type, were found in the thiarid snail Thiara tuberculata. Metacercarial cysts were found in the gills of Aplocheilus panchax, Oryzias melastigma, Gambusia affinis and Channa punctata. Adults were obtained in the small intestine of Ardeola grayi. In laboratory experiements development of cercariae into infective metacercariae took 10 days in the gills of A. panchax. Mature flukes were recovered in 10 days in the small intestine of experimentally infected 1-day-old leghorn chicks. The eggs collected from the faeces of these infected chicks were incubated at 39 degrees C. The free-swimming miracidia were found on the fifth day of incubation.

Animals↗
PubMed2003

Life cycle assessment of gasoline blending options.

A life cycle assessment has been done to compare the potential environmental impacts of various gasoline blends that meet octane and vapor pressure specifications. The main blending components of alkylate, cracked gasoline, and reformate have different octane and vapor pressure values as well as different potential environmental impacts. Because the octane and vapor pressure values are nonlinearly related to impacts, the results of this study show that some blends are better for the environment than others. To determine blending component compositions, simulations of a reformer were done at various operating conditions. The reformate products of these simulations had a wide range of octane values and potential environmental impacts. Results of the study indicate that for low-octane gasoline (95 Research Octane Number), lower reformer temperatures and pressures generally decrease the potential environmental impacts. However, different results are obtained for high-octane gasoline (98 RON), where increasing reformer temperatures and pressures increase the reformate octane values faster than the potential environmental impacts. The higher octane values for reformate allow blends to have less reformate, and therefore high-octane gasoline can have lower potential environmental impacts when the reformer is operated at higher temperatures and pressures. In the blends studied, reformate and cracked gasoline have the highest total impacts, of which photochemical ozone creation is the largest contributor (assuming all impact categories are equally weighted). Alkylate has a much lower total potential environmental impact but does have higher impact values for human toxicity by ingestion, aquatic toxicity, terrestrial toxicity, and acidification. Therefore, depending on environmental priorities, different gasoline blends and operating conditions should be chosen to meet octane and vapor pressure specifications.

Gasoline↗
PubMed1992

The life cycle of Eimeria danailovi from ducks.

The life cycle of Eimeria danailovi Gräfner, Graubmann et Betke in experimentally infected ducks was studied by optical microscopy. The asexual generation developed in the posterior part of jejunum and in the whole ileum. The sexual stages occurred in jejunum and ileum, and, in addition, in cecum and colon. All endogenous stages were localized in the cytoplasm of epithelial cells in the apical and basal parts of villi. Two generations of meronts were found to develop, differing from one another in the number of merozoites. The meronts of the first generation were observed 2 days post infection (DPI) and contained 10-14 (on the average 11) merozoites. The second generation of meronts, containing 12-22 (on the average 16) merozoites, developed on 3 DPI. The sexual stages were found in histological preparations on 5 and 6 DPI. They appeared in the faces of experimentally infected ducks first on 5 DPI and they were shed for three days. Oocyst sporulation at room temperature lasted 2-3 days.

Animals↗
PubMed2001

Comparison of different life-cycle impact assessment methods for aquatic ecotoxicity.

Human and ecotoxicity impact categories are problematic to quantify within life-cycle impact assessment (LCIA) because their local scope makes them difficult to aggregate with the traditional global-impact categories used in life-cycle assessment (LCA). For being able to assess local impacts such as toxicity, LCIA developers increasingly include fate modeling into LCA. This article follows this development by comparing different LCIA methods for aquatic ecotoxicology and by investigating the importance of fate within LCIA, the necessity of considering freshwater and seawater compartments separately, and the key degradation and intermedia transfer processes involved. The methods are compared by assessing an example study of domestic clothes washing in former West Germany. Four LCIA methods are selected and applied to four substances emitted during the washing process. The conclusion is that the consideration of environmental fate does matter and that aquatic ecotoxic impacts can differ significantly for the same substance in freshwater and in marine ecosystems. The way (bio)degradation, photolysis, volatilization, and transfer from agricultural soils are considered plays an important role as do the system boundaries chosen. This means that the LCIA methodology should remain flexible so that appropriate methods can be chosen for different applications. Fate models being developed in the environmental risk assessment of chemicals can contribute to the further improvement of LCIA methods.

Agriculture↗
PubMed1994

[Nuclear families by family life cycle category, January 1, 1992].

"In this article, family life-cycle categories [in the Netherlands] are defined by the ages of the youngest and the eldest child. The figures are from an enumeration from automated municipal population registers. For each inhabitant sex, year of birth, marital status, country of birth, family relationship and a number of other characteristics were obtained. The family relationship shows whether or not a person lives in a nuclear family and if so, what position they have therein (e.g. spouse, parent, child). On the basis of these data three types of nuclear families were defined...." (SUMMARY IN ENG)

Age Factors↗
PubMed2003

Evolution of complex life cycles in helminth parasites.

The fundamental question of how complex life cycles--where there is typically more than one host-evolve in host--parasite systems remains largely unexplored. We suggest that complex cycles in helminths without penetrative infective stages evolve by two essentially different processes, depending on where in the cycle a new host is inserted. In 'upward incorporation', a new definitive host, typically higher up a food web and which preys on the original definitive host, is added. Advantages to the parasite are avoidance of mortality due to the predator, greater body size at maturity and higher fecundity. The original host typically becomes an intermediate host, in which reproduction is suppressed. In 'downward incorporation', a new intermediate host is added at a lower trophic level; this reduces mortality and facilitates transmission to the original definitive host. These two processes should also apply in helminths with penetrative infective stages, although the mathematical conditions differ.

Animals↗
PubMed1984

Effects of host-immunity on the life cycle of Hyalomma rufipes Koch, 1844 (Ixodoidea: Ixodidae).

Studies of the effects of host-immunity on the life cycle of Hyalomma rufipes were carried out by allowing the ticks to feed on New Zealand white rabbits under laboratory conditions. The immunity of the rabbit host significantly affected the life cycle of this tick, reducing the percentage recovery of engorged females, their engorged weights and the total number of eggs laid by these females. The viability of the eggs laid by them was also considerably reduced compared to the eggs laid by females fed on naive rabbit hosts. The effects of host immunity were also revealed in the tendency towards three-host development of this species, which otherwise behaved as a two-host tick when fed on non-immune rabbit hosts.

Animals↗