Inhibition of bovine sperm‐oocyte fusion by a monoclonal antibody recognising the TEC‐2 epitope on bovine oocytes

The TEC‐2 antigenic determinant is a carbohydrate epitope located on a glycoprotein carrier molecule. In the mouse, this epitope is expressed on the zona pellucida and plasma membrane of the oocyte and is associated with the ZP2 glycoprotein and involved in the secondary sperm receptor mechanism. On the bovine oocyte expression is confined to the plasma membrane. The aim of this study was to determine the role the TEC‐2 epitope plays during fertilization in the bovine species using the monoclonal antibody TEC‐02. Incubating oocytes with the TEC‐02 antibody prior to fertilization inhibited cleavage in a dose‐dependent manner—the cleavage rate decreased as the concentration of the antibody increased. Significantly more sperm were bound to oocytes exposed to TEC‐02 (12 sperm/oocyte) compared to oocytes that were not incubated with the antibody (4 sperm/oocyte). Oocytes treated with the TEC‐02 antibody had a 7.5 ± 3.2% fusion rate and no cortical granule exocytosis compared with oocytes not exposed to the antibody, with 86.5 ± 5.8% of sperm‐oocyte fusions and release of cortical granules. The block to sperm‐oocyte fertilization observed in the pretreated group was overcome using intracytoplasmic sperm injection as the method of fertilization that bypassed the fusion process. Although sperm were binding to the oolemma these results suggest that fusion was not occurring and this may be due to the antibody occupying TEC‐2 epitope sites involved in the fusion process. In conclusion, the TEC‐2 epitope seems to be involved in sperm‐oocyte interaction in the bovine species and appears to be involved specifically during the fusion events of fertilization. Mol. Reprod. Dev. 54:173–178, 1999. © 1999 Wiley‐Liss, Inc.     

Improvement of forage production in Calliandra calothyrsus: methodology for the identification of an effective inoculum containing Rhizobium strains and arbuscular mycorrhizal isolates

The overall aim of this paper is to describe the selection of effective rhizobia and arbuscular mycorrhizas (AM), which after inoculation, will significantly improve the forage production of Calliandra calothyrsus under field conditions. To achieve this objective, the following activities were carried out: (i) establishment from both nodules and soil samples of a collection of microsymbionts (rhizobium and AM) of C. calothyrsus from Central America (Mexico, Honduras, Guatemala, Nicaragua and Costa Rica), also from outside its native range in Cameroon, Kenya and New Caledonia; (ii) identification under glasshouse conditions of the most effective rhizobia and AM isolates; (iii) production of a solid selected inoculum for field trials; (iv) examination of the impact of the inoculation on the growth of C. calothyrsus monitored under nursery conditions. We have screened 446 rhizobia strains in the nursery and identified six as being very effective at nodulating the host plant. They originated from Costa Rica (CCCR15 and CCCR1), from New Caledonia (CCNC26), from Cameroon (CCC22) and from Kenya (KWN35 and KCC6). In relation to AM, five isolates have been selected for the ability to infect and promote growth of the host plant--two isolates of Gigaspora albida isolated from Kenya (GA1b and GA2); one isolate of Scutellospora verrucosa isolated from Kenya (SV2c); one isolate of Scutellospora calospora isolated from Guatemala (SC2) and one isolate of Glomus etunicatum isolated from Honduras (GE1). Further experiments will test these selected inocula, singly and in mixtures, in order to obtain an inoculant which significantly improves the growth of C. calothyrsus and to enable its distribution to farmers who use this woody legume for forage production on their farms.     

Localisation of the Notch family in the human endometrium of fertile and infertile women

To investigate the spatial and temporal immunolocalisation and staining intensity of the Notch signalling family in endometrium of fertile and infertile women, endometrial biopsies were collected by curettage from 25 fertile women across the menstrual cycle and 10 infertile women in the mid secretory phase of menstrual cycle. Immunohisotchemistry was completed for NOTCH1, -2, -3, -4, cleaved Notch, DLL1, -3, -4, JAGGED1, -2, HES and NUMB and immunostaining intensity measured in both the endometrial glandular and luminal epithelium. NOTCH1 and the ligands DLL1 and JAGGED1 were key proteins displaying increased staining intensity during the receptive phase of the menstrual cycle and dysregulated in infertile endometrium. Conversely, NUMB a negative regulator of Notch signalling was decreased in the mid secretory phase of the menstrual cycle in fertile women and increased with infertility.     

Righting the Wrongs: Contesting Water Property Rights in Southern Ethiopia

Resolution of disputes and investigation of institutions that have attempted to right the wrongs (some of which have persisted for centuries) regarding pastoralists’ property rights over indigenous water sources in East Africa have rarely been the subject of formal study. Using a framework of water property rights, hereafter konfi, we report on contestations over rights to the ancient tula wells in southern Ethiopia, some of which have been in operation for more than 500 years. Unlike grazing lands, which are communal resources, wells are private properties managed by corporate clan members. We reconstructed the history of contests over property rights to 64 wells and found that some contests over konfi have remained unresolved for many generations. Only a small percentage (20%) of the wells have no history of disputes over property rights. The resolution of disputes relies on the principal tenet of the non-transferability of konfi property rights, except in the case of the family of the ancestral konfi dying out. Contestants are expected to reconstruct how they lost the konfi in the first place. The Borana tend to discourage contests over wells through the long duration of investigations, as well as myths associated with false claims that appeared to result in deaths among the claimants.