The In Vitro Effects of Aqueous and Ethanolic Extracts of the Leaves of Ageratum conyzoides (Asteraceae) on Three Life Cycle Stages of the Parasitic Nematode Heligmosomoides bakeri (Nematoda: Heligmosomatidae)

A comparative in vitro study was carried out to determine the ovicidal and larvicidal activity of aqueous and ethanolic extracts of Ageratum conyzoides (Asteraceae) leaves on the eggs (unembryonated and embryonated), first and second larval stages of Heligmosomoides bakeri. Four different concentrations (0.625, 1.25, 2.5, and 3.75 mg·mL−1) of both aqueous and ethanolic extracts were tested. Distilled water and 5% tween were used as negative controls in the bioassay. In fact, they did not affect development of eggs, hatching, and larval survival. The extract activities were dose dependent. The ethanolic extract was more potent against embryonation (39.6 ± 2.9%) than the aqueous extract (53.3 ± 10.9%) at the highest concentration (3.75 mg·ml−1). Both types of extracts killed larvae. Mebendazole proved more lethal (EC50 of 0.745 and 0.323 mg·mL−1, resp., for L1 and L2 larvae). The aqueous extracts were the least lethal (EC50 of 4.76 and 2.29 mg·mL−1, resp., for L1 and L2 larvae). The ethanolic extracts showed intermediate activity (EC50 of 1.323 and 1.511 mg·mL−1, resp., for L1 and L2 larvae). It is concluded that the ovicidal and larvicidal properties of aqueous and ethanolic extracts of Ageratum conyzoides leaves are demonstrated in this work

Публицистика Джафера Сейдамета в период эмиграции (1918-1960 гг.)

Background: Parasite switches to new host species are of fundamental scientific interest and may be considered an important speciation mechanism. For numerous monogenean fish parasites, infecting different hosts is associated with morphological adaptations, in particular of the attachment organ (haptor). However, haptoral morphology in Cichlidogyrus spp. (Monogenea, Dactylogyridea), parasites of African cichlids, has been mainly linked to phylogenetic rather than to host constraints. Here we determined the position of Cichlidogyrus amieti, a parasite of species of Aphyosemion (Cyprinodontiformes, Nothobranchiidae) in the phylogeny of its congeners in order to infer its origin and assess the morphological changes associated with host-switching events. Methods: The DNA of specimens of C. amieti isolated from Aphyosemion cameronense in Cameroon was sequenced and analyzed together with that of Cichlidogyrus spp. from cichlid hosts. In order to highlight the influence of the lateral transfer of C. amieti on the haptoral sclerotised parts we performed a Principal Component Analysis (PCA) to compare the attachment organ structure of C. amieti to that of congeners infecting cichlids. Results: Cichlidogyrus amieti was found to be nested within a strongly supported clade of species described from Hemichromis spp. (i.e. C. longicirrus and C. dracolemma). This clade is located at a derived position of the tree, suggesting that C. amieti transferred from cichlids to Cyprinodontiformes and not inversely. The morphological similarity between features of their copulatory organs suggested that C. amieti shares a recent ancestor with C. dracolemma. It also indicates that in this case, these organs do not seem subjected to strong divergent selection pressure. On the other hand, there are substantial differences in haptoral morphology between C. amieti and all of its closely related congeners described from Hemichromis spp.. Conclusions: Our study provides new evidence supporting the hypothesis of the adaptive nature of haptor morphology. It demonstrates this adaptive component for the first time within Cichlidogyrus, the attachment organs of which were usually considered to be mainly phylogenetically constrained

Biotope des extoparasties branchiaux de Clarias camerunensis Lonnberg, 1895 (Pisces; clariidae): modeles de croissance de l\'aire colonisable

No Abstract. JCAS Vol. 7 (1) 2007: pp. 11-1

n. sp. (Monogenea, Ancyrocephalidae) parasite stomacal de trois cichlidae endémiques du lac du cratère Barombi Mbo (Cameroun)

Description d’une nouvelle espèce : Enterogyrus barombiensis (Monogenea, Ancyrocephalidae) parasite stomacal de trois Cichlidae endémiques du lac de cratère Barombi Mbo au Cameroun. Discussion sur la spécificité parasitaire de ce Monogène

Insight into the diversity of parasites of Cyprinodontiformes (Pisces, Teleostei) from forest streams of South Cameroon, Central Africa, and their potential impact

International audienceIn order to describe the parasite fauna of the Cyprinodontiform fishes from streams located in the forest zone of the central and south plateau and the littoral plain of Cameroon and to evaluate their potential impact on their hosts by analyzing community structures, the gastrointestinal tracts and the gills of 1019 specimens of 14 Cyprinodontiform fish species belonging to the genera Aphyosemion Myers, 1924 and Epiplatys Gill, 1862 were dissected and screened for the presence of parasites. Only 149 fish specimens were found to be infected by at least one of the parasite taxa recovered. On the whole, parasitic infections in cyprinodonts, perceived on the basis of prevalence and mean abundance indices, appeared to be very low, although the parasitic fauna of some host species as A. cameronense was diversified (up to seven species). Aphyosemion cf cameronense, A. koungueense and Aphyosemion sp. showed low abundances and appeared free of ecto-and endoparasites. As micropredators, cyprinodonts acquire these endoparasites through a variety of invertebrate preys and concentrate some infective parasite stages (such as metacercariae) of several definitive hosts that prey on them. This work showed that although nematodes and trematodes, which can develop high intensities or abundances in some fish specimens, might impact their hosts (especially females) and influence their population dynamics, parasitism in general seems not to regulate the communities of the cyprinodont fish species

Four new species of Cichlidogyrus (Monogenea, Ancyrocephalidae) from Sarotherodon mvogoi and Tylochromis sudanensis (Teleostei, Cichlidae) in Cameroon

The four Cichlidogyrus species (Monogenea, Ancyrocephalidae) found on the gills of Sarotherodon mvogoi and Tylochromis sudanensis (Teleostei, Cichlidae) in Cameroon are considered new and are described herein. Cichlidogyrus mvogoi n. sp. from Sarotherodon mvogoi, characterised by a long (> 100 mu m), thin and spirally coiled penis and a short marginal hook pair I. Cichlidogyrus sigmocirrus n. sp. from Tylochromis sudanensis, characterised by a short marginal hook pair I, a slightly spirally coiled penis with reduced heel, an accessory piece being a spirally coiled band wrapped round the penis and attached to the penis basal bulb by a very thin filament. Cichlidogyrus chrysopiformis n. sp. from Tylochromis sudanensis, characterised by an marginal hook pair I of medium size, a thin spirally coiled penis (1.5 turn) with a developed flared heel, an accessory piece being a large gutter shaped band, ending in a narrow complex extremity, and linked to the basal bulb of the penis by a very thin filament, a short, straight and slightly ringed vagina. Cichlidogyrus djietoi n. sp. from Tylochromis sudanensis, characterised by a slightly spirally coiled penis (2 turns) with developed heel, an accessory piece being a large gutter shaped band, ending in a narrow folded back extremity, a short funnel shaped vagina. The three latter species are also remarkable by the morphology of their auricles implanted on the anterior side of the dorsal transverse bar which make them (together with the other species described from Tylochromis hosts) a homogeneous and original group within Cichlidogyrus, this distinctive feature seems to be ancestral compared to other Cichlidogyrus species

Acute and sub-acute toxicity of ethanolic extract of <i>Canthium mannii </i>Hiern stem bark on <i>Mus musculus</i>

146-150Acute and sub-acute toxicity of ethanolic extract (ETE) of C. mannii was assessed on white mice (Mus musculus). After 48 h of extract administration, no death was registered. It was deduced that the LD50 was indisputably higher than 16 g/kg body weight. The sub-acute toxicity test was based on the daily administration of three doses of ETE (300, 600 and 1200 mg/kg body weight) for four weeks; 1% DMSO served as negative control. As for the first experiment, no sign of toxicity was registered. Conversely, the sub acute doses stimulated and increased the weight-rate of mice after 7 days of treatment. Except for the spleen weight, the doses administrated did not modify the weight index. It was observed that, sub-acute doses induced and increased (a) the food (particularly) and water consumption according to time and (b) the number of red and white blood cells. It was thought that, ETE can stimulate the haematopoietic function. Finally, no time variation of the activity of alanine aminotransferase and aspartate aminotransferase enzyme was observed in the serum of euthanized mice. The results showed the innocuity of ETE of C. mannii and thus validated his utilization in cameroonian traditional pharmacopoea

Fish parasites

Parasitological survey of the gill filaments of Anaspidoglanis macrostoma and Parauchenoglanis monkei (Claroteidae) from the Memou'ou, a River Nyong tributary in South Cameroon, revealed the presence on these hosts of Quadriacanthus anaspidoglanii n. sp. and Bagrobdella parauchenoglanii n. sp., respectively. Quadriacanthus anaspidoglanii n. sp. is differentiated from other congeneric species by the size of haptoral parts and male copulatory complex. Bagrobdella parauchenoglanii n. sp. differs from other congeneric species by the shape and size of the male copulatory complex (not coiled penis, presence of an accessory piece). The presence of a Quadriacanthus species on an Auchenoglanidinae host (usually parasitized by monogeneans belonging to Bagrobdella) is recorded for the first time and suggests that it could be the results of a lateral transfer between hosts from these two different Siluriforme families (Clariidae and Claroteidae), living in sympatry

Enumeration of Cryptosporidium spp and Giardia spp (oo)cysts in a tropical eutrophic lake: The municipal lake of Yaounde

The biodynamic of Cryptosporidium spp. oocysts and Giadia spp. cysts have been assessed in the municipal lake of Yaounde, which is an artificial eutrophic lake that has been constructed on the Mingoa stream of the Mfoundi River Basin of Cameroon. The oocysts were identified by the Ziehl-Neelsen method while the cysts were identified by the Lugol iodine coloration. The values obtained suggest an increase in (oo)cysts density from the surface to the bottom of the lentic ecosystem. The oocysts varied from 56 oocysts/L in the upper layer to 2640 oocysts/L of water in the lowest layer, while the cysts population dynamics ranged from 24 cysts/L at the surface layer of the lake to 1713 cysts/L at the lowest layers of the lake. There was a considerable reduction in the resistant forms of these emerging pathogenic protozoa between the surface water of the Mingoa stream entering the Lake and that coming out from the Lake. The highest value of Cyptosporidium oocysts determined at the entrance of the lake is 1480 oocysts/L while at the outlet the highest value of oocysts identified is 620 oocysts/L. The highest value of Giardia cysts determined at the entrance of the lake is 352 cysts/L while at the outlet the highest value recorded is 294 cysts/L