The role of fish-poultry integration on fish growth performance,yields and economic benefits among smallholder farmers in sub-Saharan Africa,Tanzania

Aquaculture practices from sub-Saharan Africa are characterised by low production, owing to improper technology. Production can be increased through integrating fish farming with other existing on-farm activities, particularly livestock husbandry. We assessed the role of fish-poultry integration on all male Nile tilapia, Oreochromis niloticus growth performance, yields and economic benefits among smallholder farmers in sub-Saharan Africa, Tanzania. The study also compared phytoplankton species composition, abundance and biomass between the fish-poultry integration and non-integrated system. After 180 days of the experiment, all male O. niloticus cultured under fish-poultry integration exhibited significantly higher growth rates than those in the non-integrated system (p < 0.05). Gross fish yield (GFY), net fish yield (NFY) and net annual yields (NAY) obtained from fish-poultry integration were significantly higher than those from non-integrated system (p < 0.05). Partial enterprise budget analysis revealed that fish-poultry integration was more profitable than the non-integrated system. Moreover, fish-poultry integrated system produced significantly higher phytoplankton abundance and biomass than those from the non-integrated system. Results demonstrate that rural smallholder farmers can achieve higher growth rate, farm net yields and income by integrating all male O. niloticus with other on-farm activities than practising a stand-alone fish culture system.     

Floral scent evolution in the section Pseudophrys: pollinator‐mediated selection or phylogenetic constraints?

• Sexually deceptive orchid species from the Mediterranean genus Ophrys usually interact with one or a few pollinator species by means of specific floral scents. In this study, we investigated the respective role of pollinator‐mediated selection and phylogenetic constraints in the evolution of floral scents in the section Pseudophrys.
• We built a phylogenetic tree of 19 Pseudophrys species based on three nuclear loci; we gathered a dataset on their pollination interactions from the literature and from our own field data; and we extracted and analysed their floral scents using solid phase microextraction and gas chromatography‐mass spectrometry. We then quantified the phylogenetic signal carried by floral scents and investigated the link between plant–pollinator interactions and floral scent composition using phylogenetic comparative methods.
• We confirmed the monophyly of the section Pseudophrys and demonstrated the existence of three main clades within this section. We found that floral scent composition is affected by both phylogenetic relationships among Ophrys species and pollination interactions, with some compounds (especially fatty acid esters) carrying a significant phylogenetic signal and some (especially alkenes and alkadienes) generating dissimilarities between closely related Pseudophrys pollinated by different insects.
• Our results show that in the section Pseudophrys, floral scents are shaped both by pollinator‐mediated selection and by phylogenetic constraints, but that the relative importance of these two evolutionary forces differ among compound classes, probably reflecting distinct selective pressures imposed upon behaviourally active and non‐active compounds.

     

Characterization of TCR gene rearrangements during adult murine T cell development

Development of the alphabeta and gammadelta T cell lineages is dependent upon the rearrangement and expression of the TCRalpha and beta or gamma and delta genes, respectively. Although the timing and sequence of rearrangements of the TCRalpha and TCRbeta loci in adult murine thymic precursors has been characterized, no similar information is available for the TCRgamma and TCRdelta loci. In this report, we show that approximately half of the total TCRdelta alleles initiate rearrangements at the CD44highCD25+ stage, whereas the TCRbeta locus is mainly in germline configuration. In the subsequent CD44lowCD25+ stage, most TCRdelta alleles are fully recombined, whereas TCRbeta rearrangements are only complete on 10-30% of alleles. These results indicate that rearrangement at the TCRdelta locus can precede that of TCRbeta locus recombination by one developmental stage. In addition, we find a bias toward productive rearrangements of both TCRdelta and TCRgamma genes among CD44highCD25+ thymocytes, suggesting that functional gammadelta TCR complexes can be formed before the rearrangement of TCRbeta. These data support a model of lineage commitment in which sequential TCR gene rearrangements may influence alphabeta/gammadelta lineage decisions. Further, because TCR gene rearrangements are generally limited to T lineage cells, these analyses provide molecular evidence that irreversible commitment to the T lineage can occur as early as the CD44highCD25+ stage of development.     

Angiogenic factors and the endometrium following long term progestin only contraception

Endometria from long term progestin only contraceptive-treated patients display abnormally enlarged blood vessels that are prone to bleeding as well as inflammation and possibly local diminution in blood flow. Such bleeding is also characterized by focal reductions in the expression of angiopoietin-1, a vessel stabilization and maturation agent, and excess production of the potent angiogenic agents, vascular endothelial growth factor and angiopoietin-2. In addition, tissue factor, the key initiator of hemostasis may play an angiogenic role either directly or via the activation of thrombin. This review article summarizes current findings related to the endometrial dysregulation of angiogenic/hemostatic agents following treatment with long term progestin only contraception. Studies in this area offer a promising avenue to alleviate abnormal uterine bleeding associated with this otherwise highly effective form of contraception     

Versatile and efficient formation of colloids of biopolymer-based polyelectrolyte complexes

The formation of colloids based on polyelectrolyte complexes (PECs) of biopolymers was investigated through the complexation between two charged polysaccharides, chitosan as polycation, and dextran sulfate as polyanion. The slow dropwise addition of components, generally used for the formation of PECs, allowed to elaborate both cationic or anionic particles with an excess of chitosan or dextran sulfate, respectively. The PEC particles featured a core/shell structure, the hydrophobic core resulting from the segregation of complexed segments whereas excess component in the outer shell ensured the colloidal stabilization against further coagulation. Considering the host/guest concept for the formation of PECs, the influence of the molecular weight of components on particles sizes could be well explained by the chain length ratios of the two polymers. As an irreversible flocculation occurred with a dropwise approach for both cationic and anionic PEC particles when the mixing ratio was close to unity, a more versatile, and simpler to setup, method was designed: the one-shot addition of one solution to the other. Because process of addition is faster than the flocculation, cationic or anionic particles could be elaborated irrespective of the order of addition of the reactant. Characterization of these particles by quasielastic light scattering, electrophoresis, and scanning electron microscopy revealed very similar properties to those obtained by a slow dropwise approach. Critical coagulation concentrations of 0.12 and 0.09 M (with sodium chloride) for cationic and anionic particles evidenced a mostly electrostatic stabilization.     

Colony structure in a plant-ant: behavioural,chemical and genetic study of polydomy in<Emphasis Type="Italic"> Cataulacus mckeyi</Emphasis> (Myrmicinae)

Social organisation of colonies of obligate plant-ants can affect their interaction with myrmecophyte hosts and with other ants competing for the resources they offer. An important parameter of social organisation is whether nest sites of a colony include one or several host individuals. We determined colony boundaries in a plant-ant associated with the rainforest understorey tree Leonardoxa africana subsp. africana, found in coastal forests of Cameroon (Central Africa). This myrmecophyte is strictly associated with two ants, Petalomyrmex phylax and Cataulacus mckeyi. Plants provide food and nesting sites for P. phylax, which protects young leaves against insect herbivores. This mutualism is often parasitised by C. mckeyi, which uses but does not protect the host. The presence of C. mckeyi on a tree excludes the mutualistic ant. Because Petalomyrmex -occupied trees are better protected, their growth and survival are superior to those of Cataulacus -occupied trees, giving P. phylax an advantage in occupation of nest sites. C. mckeyi often colonises trees that have lost their initial associate P. phylax, as a result of injury to the tree caused by disturbance. Polydomy may allow C. mckeyi to occupy small clumps of trees, without the necessity of claustral colony foundation in each tree. Investigating both the proximate (behavioural repertoire, colony odour) and the ultimate factors (genetic structure) that may influence colony closure, we precisely defined colony boundaries. We show that colonies of C. mckeyi are monogynous and facultatively polydomous, i.e. a colony occupies one to several Leonardoxa trees. Workers do not produce males. Thus, the hypothesis that polydomy allows workers in queenless nests to evade queen control for their reproduction is not supported in this instance. This particular colony structure may confer on C. mckeyi an advantage in short-distance dispersal, and this could help explain its persistence within the dynamic Leonardoxa system.