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Neuroactive substances in reproduction and development in platyhelminths

100%

Halton D. W., Maule A. G., Shaw C.

Wiadomości Parazytologiczne

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1998

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tom 44

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nr 3

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FMRFamide-related peptides [FaRPs] in helminth parasites

80%

Halton D. W., Maule A. G., Marks N. J., Fellowes R. A., Shaw C.

Acta Parasitologica

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1999

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tom 44

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nr 1

Neuropeptides are ubiquitous intercellular signalling molecules in all Metazoa with nervous systems. Research over the past 10 years has confirmed through immunocytochemistry that neuropeptides are widespread and abundant in the nervous systems of helminth parasites. Biochemical isolation and characterisation studies have indentified the primary structures of numerous structurally- related peptides in helminths, the best studied being the FMRFamide-related peptides (FaRPs). While to date only four FaRPs have been identified from platyhelminths, some 60 FaRPs or FaRP-like peptides have been isolated or predicted for nematodes. Preliminary physiological studies have shown that FaRPs are strongly myoactive, but with quite different actions in the two groups of helminth parasite. The absence of FaRPs from vertebrates suggests compounds with a high affinity for FaRP receptors are likely to have selective effects against helminths and, if protected from degradation, could have therapeutic potential.

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An experimental study of egg assembly in the monogenean [platyhelminth] skin parasite Entobdella soleae, using a fast preservation technique and transmission electron microscopy

80%

Tappenden T., Kearn G. C.

Acta Parasitologica

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1999

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tom 44

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nr 1

Stages in the assembly of the egg in the monogenean skin parasite Entobdella soleae have been studied using a fast preservation technique for transmission electron microscopy. The first event is the release by the germarium of a fertilised oocyte, which travels to the ootype followed by many vitelline cells. There are two types of Mehlis' gland and the secretion from one of these (beta) is thought to promote the release of the vitelline droplets, which fuse peripherally in the distal tetrahedral chamber of the ootype to produce the eggshell. Initially, the zygote lodges in the distal corner of the chamber, perhaps held in place by cortical granule material, and prevents shell deposition in this corner. However, this is temporary, and when the zygote leaves the corner the opercular eggshell is laid down. The egg appendage is assembled in the proximal tubular part of the ootype and the adhesive droplets on the appendage are derived from the second (alpha) type of Mehlis' secretion.

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An ultrastructural study of the egg assembly region of the female reproductive tract of the monogenean [platyhelminth] skin parasites Entobdella soleae and E.hippoglossi

70%

Tappenden T., Kearn G. C.

Acta Parasitologica

|

1999

|

tom 44

|

nr 1

An ultrastructural study has been made of the egg assembly apparatus of the monopisthocotylean monogenean skin parasites Entobdella soleae and E. hippoglossi from the common sole, Solea solea, and the halibut, Hippoglossus hippoglossus, respectively. The ootype consists of a distal tetrahedral chamber where the egg capsule is assembled and a proximal ootype tube where the egg appendage is made. Two types of Mehlis' gland (alpha and beta) open at the proximal end of the ootype tube, which has a non-secretory lining. In both species, the tetrahedral ootype chamber has a syncytial lining, which apparently is not secretory and possesses on its luminal surface stud-like projections, each with vacuolated cytoplasm and an electron-dense core. The ootype chamber is enclosed by a single layer of muscle fibres and is embedded in a spongy "connective tissue". The uterus in E. soleae has a cellular secretory lining, with densely packed luminal microvilli.

Ograniczanie wyników

3 Acta Parasitologica

1 Wiadomości Parazytologiczne

2 Halton D. W.

2 Kearn G. C.

2 Maule A. G.

2 Shaw C.

2 Tappenden T.

1 Fellowes R. A.

1 Marks N. J.

3 1999

1 1998

Neuroactive substances in reproduction and development in platyhelminths

FMRFamide-related peptides [FaRPs] in helminth parasites

An experimental study of egg assembly in the monogenean [platyhelminth] skin parasite Entobdella soleae, using a fast preservation technique and transmission electron microscopy

An ultrastructural study of the egg assembly region of the female reproductive tract of the monogenean [platyhelminth] skin parasites Entobdella soleae and E.hippoglossi