Division of Labor in Hand Usage in Free- Ranging Bonnet Macaques, Macaca radiata

Primates exhibit laterality in hand usage either in terms of (a) hand with which an individual solves a task or while solving a task that requires both hands, executes the most complex action, that is, hand preference, or (b) hand with which an individual executes actions most efficiently, that is, hand performance. Observations from previous studies indicate that laterality in hand usage might reflect specialization of the two hands for accomplishing tasks that require maneuvering dexterity or physical strength. However, no existing study has investigated handedness with regard to this possibility. In this study, we examined laterality in hand usage in urban free-ranging bonnet macaques, Macaca radiata with regard to the above possibility. While solving four distinct food extraction tasks which varied in the number of steps involved in the food extraction process and the dexterity required in executing the individual steps, the macaques consistently used one hand for extracting food (i.e., task requiring maneuvering dexterity)the maneuvering hand, and the other hand for supporting the body (i.e., task requiring physical strength)the supporting hand. Analogously, the macaques used the maneuvering hand for the spontaneous routine activities that involved maneuvering in three-dimensional space, such as grooming, and hitting an opponent during an agonistic interaction, and the supporting hand for those that required physical strength, such as pulling the body up while climbing. Moreover, while solving a task that ergonomically forced the usage of a particular hand, the macaques extracted food faster with the maneuvering hand as compared to the supporting hand, demonstrating the higher maneuvering dexterity of the maneuvering hand. As opposed to the conventional ideas of handedness in non-human primates, these observations demonstrate division of labor between the two hands marked by their consistent usage across spontaneous and experimental tasks requiring maneuvering in three-dimensional space or those requiring physical strength. Am. J. Primatol. 76:576-585, 2014. (c) 2013 Wiley Periodicals, Inc.

Mycobacterium tuberculosis Cell Division Protein, FtsE, is an ATPase in Dimeric Form

FtsE is one of the earliest cell division proteins that assembles along with FtsX at the mid-cell site during cell division in Escherichia coli. Both these proteins are highly conserved across diverse bacterial genera and are predicted to constitute an ABC transporter type complex, in which FtsE is predicted to bind ATP and hydrolyse it, and FtsX is predicted to be an integral membrane protein. We had earlier reported that the MtFtsE of the human pathogen, Mycobacterium tuberculosis, binds ATP and interacts with MtFtsX on the cell membrane of M. tuberculosis and E. coli. In this study, we demonstrate that MtFtsE is an ATPase, the active form of which is a dimer, wherein the participating monomers are held together by non-covalent interactions, with the Cys84 of each monomer present at the dimer interface. Under oxidising environment, the dimer gets stabilised by the formation of Cys84-Cys84 disulphide bond. While the recombinant MtFtsE forms a dimer on the membrane of E. coli, the native MtFtsE seems to be in a different conformation in the M. tuberculosis membrane. Although disulphide bridges were not observed on the cytoplasmic side (reducing environment) of the membrane, the two participating monomers could be isolated as dimers held together by non-covalent interactions. Taken together, these findings show that MtFtsE is an ATPase in the non-covalent dimer form, with the Cys84 of each monomer present in the reduced form at the dimer interface, without participating in the dimerisation or the catalytic activity of the protein.

The tarani mutation alters surface curvature in Arabidopsis leaves by perturbing the patterns of surface expansion and cell division

The leaf surface usually stays flat, maintained by coordinated growth. Growth perturbation can introduce overall surface curvature, which can be negative, giving a saddle-shaped leaf, or positive, giving a cup-like leaf. Little is known about the molecular mechanisms that underlie leaf flatness, primarily because only a few mutants with altered surface curvature have been isolated and studied. Characterization of mutants of the CINCINNATA-like TCP genes in Antirrhinum and Arabidopsis have revealed that their products help maintain flatness by balancing the pattern of cell proliferation and surface expansion between the margin and the central zone during leaf morphogenesis. On the other hand, deletion of two homologous PEAPOD genes causes cup-shaped leaves in Arabidopsis due to excess division of dispersed meristemoid cells. Here, we report the isolation and characterization of an Arabidopsis mutant, tarani (tni), with enlarged, cup-shaped leaves. Morphometric analyses showed that the positive curvature of the tni leaf is linked to excess growth at the centre compared to the margin. By monitoring the dynamic pattern of CYCLIN D3;2 expression, we show that the shape of the primary arrest front is strongly convex in growing tni leaves, leading to excess mitotic expansion synchronized with excess cell proliferation at the centre. Reduction of cell proliferation and of endogenous gibberellic acid levels rescued the tni phenotype. Genetic interactions demonstrated that TNI maintains leaf flatness independent of TCPs and PEAPODs.

Asymmetric cell division of granule neuron progenitors in the external granule layer of the mouse cerebellum

The plane of division of granule neuron progenitors (GNPs) was analysed with respect to the pial surface in P0 to P14 cerebellum and the results showed that there was a significant bias towards the plane of cell division being parallel to pial surface across this developmental window. In addition, the distribution of beta-Catenin in anaphase cells was analysed, which showed that there was a significant asymmetry in the distribution of beta-Catenin in dividing GNPs. Further, inhibition of Sonic Hedgehog (Shh) signalling had an effect on plane of cell division. Asymmetric distribution of beta-Catenin was shown to occur towards the source of a localized extracellular cue.

Regulation of Growth, Cell Shape, Cell Division, and Gene Expression by Second Messengers (p)ppGpp and Cyclic Di-GMP in Mycobacterium smegmatis

The alarmone (p)ppGpp regulates transcription, translation, replication, virulence, lipid synthesis, antibiotic sensitivity, biofilm formation, and other functions in bacteria. Signaling nucleotide cyclic di-GMP (c-di-GMP) regulates biofilm formation, motility, virulence, the cell cycle, and other functions. In Mycobacterium smegmatis, both (p) ppGpp and c-di-GMP are synthesized and degraded by bifunctional proteins Rel(Msm) and DcpA, encoded by rel(Msm) and dcpA genes, respectively. We have previously shown that the Delta rel(Msm) and Delta dcpA knockout strains are antibiotic resistant and defective in biofilm formation, show altered cell surface properties, and have reduced levels of glycopeptidolipids and polar lipids in their cell wall (K. R. Gupta, S. Kasetty, and D. Chatterji, Appl Environ Microbiol 81:2571-2578, 2015, http://dx.doi.org/10.1128/AEM.03999-14). In this work, we have explored the phenotypes that are affected by both (p) ppGpp and c-di-GMP in mycobacteria. We have shown that both (p) ppGpp and c-di-GMP are needed to maintain the proper growth rate under stress conditions such as carbon deprivation and cold shock. Scanning electron microscopy showed that low levels of these second messengers result in elongated cells, while high levels reduce the cell length and embed the cells in a biofilm-like matrix. Fluorescence microscopy revealed that the elongated Delta rel(Msm) and Delta dcpA cells are multinucleate, while transmission electron microscopy showed that the elongated cells are multiseptate. Gene expression analysis also showed that genes belonging to functional categories such as virulence, detoxification, lipid metabolism, and cell-wall-related processes were differentially expressed. Our results suggests that both (p) ppGpp and c-di-GMP affect some common phenotypes in M. smegmatis, thus raising a possibility of cross talk between these two second messengers in mycobacteria. IMPORTANCE Our work has expanded the horizon of (p) ppGpp and c-di-GMP signaling in Gram-positive bacteria. We have come across a novel observation that M. smegmatis needs (p) ppGpp and c-di-GMP for cold tolerance. We had previously shown that the Delta rel(Msm) and Delta dcpA strains are defective in biofilm formation. In this work, the overproduction of (p) ppGpp and c-di-GMP encased M. smegmatis in a biofilm-like matrix, which shows that both (p) ppGpp and c-di-GMP are needed for biofilm formation. The regulation of cell length and cell division by (p) ppGpp was known in mycobacteria, but our work shows that c-di-GMP also affects the cell size and cell division in mycobacteria. This is perhaps the first report of c-di-GMP regulating cell division in mycobacteria.