Studies on vertical transmission of Trichinella spp. in experimentally infected ferrets (Mustela putorius furo), foxes (Vulpes vulpes), pigs, guinea pigs and mice

Vertical transmission of Trichinella spiralis was evaluated in ferrets (n = 21), foxes (n = 11), pigs (n = 12), guinea pigs (n = 16), and mice (n = 41). The placental barrier to be crossed by migratory Trichinella larvae varies structurally in different animal species. Ferrets and foxes have an endotheliochorial placenta structure, guinea pigs and mice a haemochorial, and pigs an epitheliochorial placenta. The non-encapsulating Trichinella pseudospiralis larvae have an extended muscle migration prior to entering a muscle cell. To evaluate if T. pseudospiralis was more likely to be transmitted to offspring, an additional group of foxes (n = 11) infected with T. pseudospiralis was included. Two different dose levels were used for ferrets, pigs, guinea pigs, and mice. In pigs and guinea pigs, infection was given at different times of the gestation period. Vertical transmission, measured as recovery of muscle larvae in the offspring, was demonstrated in both ferrets groups, in all four guinea pig groups, and in the high dose mouse group, but not in any fox or pig groups.     

Synchronous neural activity recorded from the round window

AIM: To study the origin of the 1kHz peak of average spectrum electrophysiological cochleoneural activity (ASECA-1kHz), which is related to the firing of auditory neurous-a possible synchronized firing. METHODS: By using the various sound presented either ipsilaterally or contralaterally, the alterations of ASECA-1kHz were detected under the state of awakness. RESULTS: (1) Contralateral stimulation with noise bands at frequencies above 8kHz and below acoustic interaural cross-talk decreased the amplitude of ASECA-1kHz. (2) For the presentations of ipsilaterally noises, when the acoustic bandwidth was above or below 1.5kHz, then produced respectively an increase or a decrease of ASECA-1kHz. (3) Pure tones when presented contralaterally had no detectable effect, but when presented ipsilaterally pure tones with frequencies higher than 4kHz decreased the ASECA-1kHz. Moreover, the detailed time course of sound-induced variations of the 1kHz peak was measured by time averaging, the resulting response patterns were resemblance to PST histogram of the auditory nerve. CONCLUSIONS: The results suggest that the ASECA-1kHz peak in the guinea pig originates from a restricted tonotopic area corresponding to the high frequencies of 12.5-25 kHz and that it should correspond to a synchronized spontaneous firing of fibers.     

Effect of BCG on experimental asthma in a guinea pigmodel of allergen sensitization

AIM: To examine the effect of bacillus calmette-guerin (BCG) on experimental asthma in guinea pigs. METHODS: Guinea pigs were sensitized with BCG and then with ovalbumin (ip). Two weeks later, guinea pigs were challenged with ovalbumin (OVA) aerosol inhalation. Thirty one Guinea pigs were divided into three groups at random control group,OVA-treated group, BCG and OVA-treated group.RESULTS: Ovalbumin inhalation caused a marked airway infiltration of eosinophils and all the animals exhibit asthmatic symptoms. Pretreatment with BCG induced typical increase in lymphocytes and monocytes in peripheral blood and in bronchoalveolar lavage fluid (BALF). BCG markedly inhibited eosinophil infiltration and attenuated the asthmatic symptoms. CONCLUSION: These data suggest that BCG exerts an inhibitory effect on asthmatic inflammation.     

Animal production and genetic resources in Guinea Bissau: I – Northern <Emphasis Type="Italic">Cacheu</Emphasis> Province

A survey of the animal production systems and genetic resources was conducted in Northern Cacheu Province, Guinea Bissau. Animal owners and their families, village chiefs, shepherds and local officials were interviewed. The vast majority of the population is dedicated to very small-scale subsistence farming where animal ownership has an important role in both food supply, ceremonial events and as form of cash reserve. Cattle (N'Dama and West African Shorthorn breeds) are owned by the two larger ethnic groups in the area, the Felupes and the Balantas that have however different management practices. Sheep are relatively scarce whereas goats (West African Dwarf) are the most important small ruminant species for both ethnic groups. Pigs (crioulo breed) and dwarf chickens play a very important role as they are the only species regularly used in trade at the village level.     

Nodulation and estimation of symbiotic nitrogen fixation by herbaceous and shrub legumes in Guinea savanna in Nigeria

Twelve herbaceous and shrub legume species were grown in pot and field experiments in five sites representing three agroecological zones in moist savanna in Nigeria. The objectives were to: (1) assess natural nodulation of the legumes and characterize their indigenous rhizobia, (2) determine their need for rhizobia inoculation and (3) estimate the amount of N₂ fixed by each of these legumes. At 4 weeks after planting (WAP), Crotolaria verrucosa was not nodulated at any of the sites while Centrosema pascuorum had the highest number of nodules in all sites. At 8 WAP, all legumes were nodulated, with Mucuna pruriens having the least number of nodules and Stylosanthes hamata the highest. The number of nodules, however, was inversely correlated to the mass of nodules. Significant differences in nodulation of the legume species grown in the field also occurred between and within sites. Mucuna pruriens and Lablab purpureus produced more shoot and nodule biomass than the other legumes in all sites. Growth of most of these legumes responded to fertilizer application, except for C. verrucosa and Aeschynomene histrix. Except for C. verrucosa, average proportion of N₂ fixed was about 80% and this was reduced by about 20% with N fertilizer application. The majority of rhizobia isolates (60%) were slow growing, belonging to the Bradyrhizobia spp. group. Selected rhizobia isolates evaluated on Cajanus cajan, C. pascuorum, M. pruriens and Psophocarpus palustris varied from ineffective to highly effective in Leonard jar conditions. However, only growth of M. pruriens responded to inoculation in potted soils, whereas it was lower than that obtained with N fertilizer application. This indicated the need to screen more rhizobia in order to improve N₂ fixation and growth of legume species such as M. pruriens when it is introduced in soils deficient in N.     

Determinants of urban bushmeat consumption in Río Muni, Equatorial Guinea

Understanding the factors driving demand for wild meat and its substitutes is crucial for predicting the effects of changing socio-economic conditions on consumption, and managing supplies sustainably. However urban demand for wild meat remains relatively understudied, particularly in West/Central Africa. We use interviews with consumers in households, markets and restaurants and a market survey to examine patterns of consumption of bushmeat, domestic meat and fish in Bata, Equatorial Guinea, a country currently undergoing a period of strong economic and population growth. Consumers make a much clearer distinction between fresh and frozen foods than between bushmeat, domestic meat and fish. Fresh foods are greatly preferred over frozen but are more expensive and less consumed. Consumption of all fresh foods increases with income. Controlling for income, native Equatoguineans consume more bushmeat than other nationalities, while of the two dominant Equatoguinean tribes, the continental Fang consume more bushmeat than the coastal Ndowe. Our findings indicate that increasing wealth of a growing urban population will greatly increase future demand for all fresh foods, including bushmeat. There is no evidence of a luxury bushmeat market based on rare species, thus controlled demand for bushmeat could be met from common, highly productive species that are relatively robust to exploitation. Improving the supply of under-developed commodities, particularly domestic livestock, could also offset demand for bushmeat.     

Yam (Dioscorea ssp.) domestication by the Nago and Fon ethnic groups in Benin

Guinea yams (Dioscorea cayenensis-rotundata complex; D. rotundata Poir. and D. cayenensis Lam.) have been described as resulting from a process of domestication of wild yams of the section Enantiophyllum by African farmers. Although currently practised by few farmers, the process of yam domestication is still on-going in Benin. In order to document the practices used and the indigenous knowledge maintained by Nago and Fon farmers, 27 villages were surveyed. In total, 57 farmers domesticating yam were identified, and 68 yams newly domesticated (or in domestication) were collected. Fon and Nago farmers domesticate yam mainly to widen the genetic basis of the existing diversity or for simple curiosity. Among the three wild yams species (D. abyssinica Hochst. ex Kunth, D. praehensilis Benth. and D. burkilliana J. Miège) used, D. praehensilis is the most important and the most exploited. Tuber of the wild yams are collected either in the bush (most often near the village) or in the forests (far from the village) during hunting. The domestication process consists of bringing into cultivation selected individuals which go through intense vegetative multiplication and selection procedures (over a lengthy but variable period of time) that induce morphological and biochemical changes in the plant mainly at the tuber level. Individuals resulting from these manipulations were found to be, either similar or identical to known landraces or completely new based on both morphological and isozyme analysis. Because it leads to some new cultivars, this process of domestication has potential in yam breeding and appears to be a strategy that could be useful to breeders, while developing a methodology for participatory breeding of yam.     

用甘蓝夜蛾核型多角体病毒感染豚鼠

用纯化的甘蓝夜蛾核型多角体病毒悬液,按4×10~6PIB/克体重剂量,经腹腔接种豚鼠,在第6天和第16天解剖取胰脏,超薄切片电镜观察,可在胰脏细胞内发现多角体病毒;用豚鼠肝、脾和胰等脏器匀浆液饲养棉铃虫幼虫,被感染虫患典型病毒病,死虫率6天解剖的豚鼠为70.83%,16天解剖者为91.3%; 病死虫脓计在扫描电镜下发现典型多角体.据此可确定甘蓝夜蛾核型多角体病毒在豚鼠脏器内滞留16天.至于豚鼠脏器细胞是否复制该病毒问题,尚需进一步研究.     

Divided communities and contested landscapes: Mobility,development and shifting identities in migrant destination sites in Papua New Guinea

Abstract: Internal conflicts at the local and national levels in several South Pacific countries have revealed the fragility of national unity and the difficulties nations face in governing and managing their own economic development. In Papua New Guinea, the focus of this paper, an uncertain economic future for many rural and urban communities, and rising inequalities in income opportunities and access to resources, have coincided with greater intolerance of migrants at sites of high in‐migration by customary landowners and provincial and local authorities. This paper draws on fieldwork undertaken in the major oil palm growing regions of Papua New Guinea where migrants from densely populated regions of the country have settled on state land alienated from customary landowners. We examine how struggles over land, resource control and development are polarising migrant and landowner identities resulting in increasing tensions and episodic communal violence. A settler identity is emerging based on a narrative of nation building and national development, while an ethno‐regional identity amongst customary landowners is undermining the citizen rights of migrants and challenging the role and authority of the state in land matters.