Physiological Aspects of Reproduction in Nematodes

Anya, A. O.

doi:10.1016/s0065-308x(08)60516-3

Cited by 57 publications

(31 citation statements)

References 199 publications

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“…They possess that resistance thanks to three factors. First, to the construction of egg membranes composed of three layers -the internal consisting of ascarosides, middle -chitin and external -glycoproteins (Lyšek et al, 1985;Polyakowa-Krustewa et al, 1985), second, the large quantities of stored energy reserves (particularly triacylglycerols and carbohydrates) and finally, the ability to ………….. adjust the pace of metabolism to the external conditions (Anya, 1976). The development of embryos in A. suum eggs progresses according to the pattern typical for nematodes (Conn, 1991;Schierenberg et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Changes in trehalase activity and trehalose level during Ascaris suum (Nematoda) embryogenesis

et al. 2006

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130 SummaryThe levels of trehalose and the activity of trehalase during the development of Ascaris suum eggs were investigated. The level of trehalose in the zygote was high (2.96 ± 0.07 mg/g). During cleavage of eggs, it decreased (0.91 ± 0.35 mg/g). A higher concentration of the sugar was recorded at the blastula and during gastrulation, but it did not reach the uncleaved eggs level. In the early motile larvae, the concentration of trehalose was high (4.58 ± 2.01 mg/g). It decreased with development of L 1 larvae (3.10 ± 1.47 mg/g). A rapid increase in trehalose reserves was observed between the L 1 and L 2 stages. The highest content of trehalose was found in invasive L 2 larvae (5.78 ± 1.39 mg/g). The activity of trehalase at the zygote stage was high (560.22 ± 322.31 U/mg). It decreased at the beginning of cleavage. It was the lowest at the 4 -6-cell stage (189.76 ± 114.97 U/mg). An increase in the enzyme activity occurred after reaching the blastula stage (348.44 ± 343.34 U /mg). The highest trehalase activity was recorded during the L 1 larvae stage (635.72 ± 251.16 U/mg). The activity of that enzyme was about three times lower in the invasive stage larvae than in the L 1 larvae.

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Section: Introductionmentioning

confidence: 99%

Changes in trehalase activity and trehalose level during Ascaris suum (Nematoda) embryogenesis

et al. 2006

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“…While exclusively asexual organisms are thought to be rare, organisms with facultative parthenogenesis, the ability to produce offspring sexually or asexually, are more common. Many insect species, such as aphids and cockroaches, as well as nematodes have the ability to produce either females asexually or males and females sexually (2,11,43). Many lower eukaryotes reproduce asexually; in the cases of yeasts and filamentous fungi, 20% or more of species have no defined sexual cycle (19).…”

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confidence: 99%

Sexual Cycle of Cryptococcus neoformans var. grubii and Virulence of Congenic a and α Isolates

Nielsen

Cox²,

Wang³

et al. 2003

Infect Immun

380

298

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Cryptococcus neoformans is a human-pathogenic fungus that has evolved into three distinct varieties that infect most prominently the central nervous system. A sexual cycle involving haploid cells of a and ␣ mating types has been reported for two varieties (C. neoformans var. neoformans, serotype D, and C. neoformans var. gattii, serotypes B and C), yet the vast majority of infections involve a distinct variety (C. neoformans var. grubii, serotype A) that has been thought to be clonal and restricted to the ␣ mating type. We recently identified the first serotype A isolate of the a mating type which had been thought to be extinct (strain 125.91). Here we report that this unusual strain can mate with a subset of pathogenic serotype A strains to produce a filamentous dikaryon with fused clamp connections, basidia, and viable recombinant basidiospores. One meiotic segregant mated poorly with the serotype A reference strain H99 but robustly with a crg1 mutant that lacks a regulator of G protein signaling and is hyperresponsive to mating pheromone. This meiotic segregant was used to create congenic a and ␣ mating type serotype A strains. Virulence tests with rabbit and murine models of cryptococcal meningitis showed that the serotype A congenic a and ␣ mating type strains had equivalent virulence in animal models, in contrast to previous studies linking the ␣ mating type to increased virulence in congenic serotype D strains. Our studies highlight a role for sexual recombination in the evolution of a human fungal pathogen and provide a robust genetic platform to establish the molecular determinants of virulence.

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“…A terminal duct, lined with cuticle and often vesiculate, opens into a central spherical sinus (there is no transverse canal) from which leave the prominent anterior and posterior lateral canals. Anya (1976) reviewed ultrastructural studies on spermatozoa of 23 nematode species and commented on the uniqueness of sperm of oxyurids. They are comet-shaped, each consisting of a headend devoid of organelles and capable of pseudopod formation, and a tail-end containing nuclear material (Lee & Anya, 1967;Foor, 1970).…”

Section: Discussionmentioning

confidence: 99%

Rhigonema infecta (Leidy, 1849) Christie & Cobb, 1927 and the systematic position of the Rhigonematidae sensu Th�odorid�s, 1965

Adamson

1981

Syst Parasitol

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Rhigonema infecta (Leidy, 1849) Christie & Cobb, 1927, a member of the family Rhigonematidae sensu Th6odorid~s, 1965, is redescribed from the diplopod Narceus annularis from Sharbot Lake and Long Point, Ontario, Canada. R. infecta is most similar to R. subtruncatum Dollfus, 1952 but differs from this species in possessing four rather than three post-cloacal papillae in the male. Rhigonematids have been affiliated with members of the order Oxyurida by most authors but study of R. infecta suggests that rhigonematids should be placed in their own order, the Rhigonematida. Members of the order Rhigonematida are characterized by: two spicules in the male; H-shaped excretory system; are round to oval sperms; thick and smooth egg-shell; apparently lacking a uterine layer; and development in the egg involving no moults and resulting in a long, thin, coiled larva. In contrast, oxyuridans have a single spicule, the excretory system is Xshaped, the sperm is comet-shaped and the egg-shell has a prominent striated uterine layer. Development in the egg involves at least one and probably two moults and results in a short, robust, uncoiled larva.

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Physiological Aspects of Reproduction in Nematodes

Cited by 57 publications

References 199 publications

Changes in trehalase activity and trehalose level during Ascaris suum (Nematoda) embryogenesis

Changes in trehalase activity and trehalose level during Ascaris suum (Nematoda) embryogenesis

Sexual Cycle of Cryptococcus neoformans var. grubii and Virulence of Congenic a and α Isolates

Rhigonema infecta (Leidy, 1849) Christie & Cobb, 1927 and the systematic position of the Rhigonematidae sensu Th�odorid�s, 1965

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