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Four Bambara groundnut landraces (Vigna subterranea(L.) Verdc.) of African origin (S-165 A, DodR, Uniswa red and SB-42), were grown at research farm of Central Arid Zone Research Institute, Regional Research Station, Bikaner to evaluate for heat tolerance based on the cell membrane thermostability of leaf tissue by using five temperature treatments (40, 45, 50, 55 and 60 °C) and four heating durations (15, 30, 45 and 60 min). Lethal temperature and lethal heating duration was used as the selection criteria for heat tolerance. Significant genotypic variations were evident for both lethal temperature and lethal heating duration. A strong relationship between lethal temperature and lethal heating duration indicates that any one of two parameters can be used as selection criteria for screening Bambara groundnut genotypes for heat tolerance. However, the range of lethal temperature was too narrow (47.5–49.4 °C), whereas the range of lethal heating duration was fairly longer (39.9–48 min) to distinguish the genotypes. Further, there was strong and significant relationship between lethal heating duration and relative injury under heat stress at 50 °C. From this study it can be concluded that lethal heating duration at 50 °C is a potential selection criterion for identifying heat tolerant genotypes in Bambara groundnut.

Cullins function as scaffolds that, along with F-box/WD40-repeat-containing proteins, mediate the ubiquitination of proteins to target them for degradation by the proteasome. We have identified a cullin CulA that is required at several stages during Dictyostelium development. culA null cells are defective in inducing cell-type-specific gene expression and exhibit defects during aggregation, including reduced chemotaxis. PKA is an important regulator of Dictyostelium development. The levels of intracellular cAMP and PKA activity are controlled by the rate of synthesis of cAMP and its degradation by the cAMP-specific phosphodiesterase RegA. We show that overexpression of the PKA catalytic subunit (PKAcat) rescues many of the culA null defects and those of cells lacking FbxA/ChtA, a previously described F-box/WD40-repeat-containing protein, suggesting CulA and FbxA proteins are involved in regulating PKA function. Whereas RegA protein levels drop as the multicellular organism forms in the wild-type strain, they remain high in culA null and fbxA null cells. Although PKA can suppress the culA and fbxA null developmental phenotypes, it does not suppress the altered RegA degradation, suggesting that PKA lies downstream of RegA, CulA, and FbxA. Finally, we show that CulA, FbxA, and RegA are found in a complex in vivo, and formation of this complex is dependent on the MAP kinase ERK2, which is also required for PKA function. We propose that CulA and FbxA regulate multicellular development by targeting RegA for degradation via a pathway that requires ERK2 function, leading to an increase in cAMP and PKA activity.

The major surface glycoprotein (gp63) of Leishmania amazonensis is a metalloprotease implicated in the infection of mammalian macrophages. The expression of gp63 and its participation in this infection were further examined by modulating the level of this molecule in a virulent gp63-abundant wild-type clone. Promastigotes were transfected with gp63 genes cloned into a Leishmania-specific vector in two different orientations, leading to the expression of gp63 sense and antisense RNAs. With increasing selective pressure, cell surface gp63 was increasingly augmented in the transfectants with sense transcripts and suppressed to a very low level in those with antisense transcripts. Thus, the expression of gp63 from chromosomal, repetitive genes is not stringently regulated at the protein level and can be substantially reduced by episomal antisense transcription of a single copy. The transfectants differed significantly only in the level of gp63, thereby allowing specific evaluation of this molecule in leishmanial infection of macrophages in vitro. Kinetic studies of infection in vitro indicate that gp63 plays a role not only in the binding of this parasite to these macrophages but also in its intramacrophage survival and replication.

Formation of somatic embryoids was noted in cell suspensions of Plantago ovata Forsk. The callus was induced on a solid Murashige and Skoog medium supplemented with 2,4-dichlorophenoxyacetic acid (1 µM) and kinetin (2 µM) using leaf explants of 12 day old seedlings. After two subcultures on the same medium, embryogenic cell suspensions with various stages of embryoids were obtained. Addition of higher levels of kinetin caused these embryos to undergo normal germination.