Was “Lucy” more human than her “child”? Observations on early hominid postcranial skeletons

Fully adult partial skeletons attributed to Australopithecus afarensis (AL 288-1, “Lucy”) and to Homo habilis (OH 62, “Lucy's child”), respectively, both include remains from upper and lower limbs. Relationships between various limb bone dimensions of these skeletons are compared to those of modern African apes and humans. Surprisingly, it emerges that OH 62 displays closer similarities to African apes than does AL 288-1. Yet A. afarensis, whose skeleton is dated more than 1 million years earlier, is commonly supposed to be the ancestor of Homo habilis. If OH 62, classified as Homo habilis by its discoverers, does indeed represent a stage intermediate between A. afarensis and later Homo, a revised interpretation of the course of human evolution would be necessary.     

Identification of the reactive cysteine residues in yeast dipeptidyl peptidase III

Dipeptidyl peptidases III (DPPs III) form a distinct metallopeptidase family characterized by the unique HEXXGH motif. High susceptibility to inactivation by organomercurials suggests the presence of a reactive cysteine residue(s) in, or close to, their active site. Yeast DPP III contains five Cys, none of which is absolutely conserved within the family. In order to identify reactive residue(s), site-directed mutagenesis on yeast His₆-tagged DPP III was employed to substitute specifically all five cysteine residues to serine. The variant enzymes thus obtained were enzymatically active and showed an overall structure not greatly affected by the mutations as judged by circular dichroism. Analysis by native and SDS-PAGE under non-reducing conditions revealed the existence of a monomeric and dimeric form in all DPP III proteins except in the C130S, implying that dimerization of yeast DPP III is mediated by the surface-exposed cysteine 130.     

Observations of neutral buoyancy in diapausing copepods Calanoides acutus during Antarctic winter

The herbivorous Antarctic copepod Calanoides acutus overwinters inactively in a resting stage (diapause) at depths below 500 m. It is assumed that during diapause C. acutus is neutrally buoyant in order to retain energy reserves otherwise depleted by swimming activities. However, so far, no experimental observations on its buoyancy have been reported and our knowledge of buoyancy regulation mechanisms is incomplete. In the present study, species-specific differences in buoyancy were assessed visually. Observations were made of specimens from the diapausing cohort of C. acutus and compared to another herbivorous copepod Calanus propinquus, which overwinters actively feeding in the upper water layers. Freshly caught copepods were anaesthetized in a 3-amino-benzoic acid ethyl ester (MS222) in seawater solution in order to exclude the influence of swimming movements on buoyancy control. It was shown that C. propinquus was negatively buoyant, whereas diapausing C. acutus remained neutrally buoyant. This is the first record that neutral buoyancy in diapausing copepods is maintained by the biochemical body composition without the additional need of swimming movements.     

Potential for Marker-Assisted Simultaneous Improvement of Grain and Biomass Yield in Triticale

Triticale is a promising crop for agricultural biomass production but breeding has until now mainly focused on grain yield. Here, we evaluated the potential of marker-assisted simultaneous improvement of grain yield and biomass yield. To this end, we employed a large triticale doubled haploid population with 647 individuals derived from four families that were phenotyped for grain yield and biomass yield, as well as thousand-kernel weight, tiller density, and plant height in multi-environment field trials. Employing an association mapping approach, we identified quantitative trait loci (QTL) for all the five traits. The phenotypic correlation between grain yield and biomass yield was low, and we detected only one overlapping QTL suggesting different genetic architectures underlying both traits. Our results indicate that a marker-based selection for either grain yield or biomass yield does not adversely affect the other traits. Furthermore, an improvement of the multiplicative yield traits can to some extent also be achieved by selection for QTL identified for the component traits. Taken together, our results suggest that marker-assisted breeding can assist the establishment of dual-purpose triticale cultivars with high grain and biomass yield.     

Functional analysis of D-alanylation of lipoteichoic acid in the probiotic strain Lactobacillus rhamnosus GG

Lipoteichoic acid (LTA) is a macroamphiphile molecule which performs several functions in gram-positive bacteria, such as maintenance of cell wall homeostasis. D-alanylation of LTA requires the proteins encoded by the dlt operon, and this process is directly related to the charge properties of this polymer strongly contributing to its function. The insertional inactivation of dltD of the probiotic strain Lactobacillus rhamnosus GG (ATCC 53103) resulted in the complete absence of D-alanyl esters in the LTA as confirmed by nuclear magnetic resonance analysis. This was reflected in modifications of the bacterial cell surface properties. The dltD strain showed 2.4-fold-increased cell length, a low survival capacity in response to gastric juice challenge, an increased sensitivity to human beta-defensin-2, an increased rate of autolysis, an increased capacity to initiate growth in the presence of an anionic detergent, and a decreased capacity to initiate growth in the presence of cationic peptides compared to wild-type results. However, in vitro experiments revealed no major differences for adhesion to human intestinal epithelial cells, biofilm formation, and immunomodulation. These properties are considered to be important for probiotics. The role of the dlt operon in lactobacilli is discussed in view of these results.     

Gene expression studies of developing bovine <Emphasis Type="Italic">longissimus</Emphasis>muscle from two different beef cattle breeds

Background  

The muscle fiber number and fiber composition of muscle is largely determined during prenatal development. In order to discover genes that are involved in determining adult muscle phenotypes, we studied the gene expression profile of developing fetal bovine longissimus muscle from animals with two different genetic backgrounds using a bovine cDNA microarray. Fetal longissimus muscle was sampled at 4 stages of myogenesis and muscle maturation: primary myogenesis (d 60), secondary myogenesis (d 135), as well as beginning (d 195) and final stages (birth) of functional differentiation of muscle fibers. All fetuses and newborns (total n = 24) were from Hereford dams and crossed with either Wagyu (high intramuscular fat) or Piedmontese (GDF8 mutant) sires, genotypes that vary markedly in muscle and compositional characteristics later in postnatal life.     

Phosphoinositide-regulated retrograde transport of ricin: crosstalk between hVps34 and sorting nexins

The plant toxin ricin is transported from the plasma membrane via early endosomes and the Golgi apparatus to the endoplasmic reticulum. From this compartment, it enters the cytosol and inhibits protein synthesis. Lipid phosphorylation is an important regulator of vesicular transport, and in the present study we have investigated the role of the phosphatidylinositol (PI) 3-kinase hVps34 in retrograde transport of ricin. Our data demonstrate that transport of ricin from endosomes to the Golgi apparatus in human embryonic kidney cells (HEK 293) is dependent on PI(3)P. By using PI 3-kinase inhibitors, by sequestering the hVps34 product PI(3)P and by expressing mutants of hVps34 or small interfering RNA targeted against its messenger RNA, we show that hVps34 and its product PI(3)P are involved in transport of ricin from endosome to Golgi apparatus. Furthermore, we identify two effector proteins in the hVps34-dependent pathway, namely sorting nexin (SNX) 2 and SNX4. Knockdown of SNX2 or SNX4 inhibits ricin transport to the Golgi apparatus to the same extent as when hVps34 is perturbed. Furthermore, inhibition or knockdown of hVps34 redistributes these proteins. Interestingly, knocking down both SNX2 and SNX4 results in a better inhibition than knocking down only one of them, suggesting that they may act on separate pathways.     

Nxf3 is expressed in Sertoli cells, but is dispensable for spermatogenesis

In eukaryotes, mRNA is actively exported to the cytoplasm by a family of nuclear RNA export factors (NXF). Four Nxf genes have been identified in the mouse: Nxf1, Nxf2, Nxf3, and Nxf7. Inactivation of Nxf2, a germ cell-specific gene, causes defects in spermatogenesis. Here we report that Nxf3 is expressed exclusively in Sertoli cells of the postnatal testis, in a developmentally regulated manner. Expression of Nxf3 coincides with the cessation of Sertoli cell proliferation and the beginning of their differentiation. Continued expression of Nxf3 in mature Sertoli cells of the adult is spermatogenesis stage-independent. Nxf3 is not essential for spermatogenesis, however, suggesting functional redundancy among Nxf family members. With its unique expression pattern in the testis, the promoter of Nxf3 can be used to drive postnatal Sertoli cell-specific expression of other proteins such as Cre recombinase.     

Neuropeptide profiling of the bovine hypothalamus: thermal stabilization is an effective tool in inhibiting post-mortem degradation

The hypothalamus is the central regulatory region of the brain that links the nervous system to the endocrine system via the pituitary gland. It synthesizes and secretes neuropeptide hormones, which in turn act to stimulate or inhibit the secretion of pituitary hormones. We have undertaken a detailed MS investigation of the peptides present in the bovine hypothalamus by adapting a novel heat stabilization methodology, which improved peptide discovery to direct our studies into the molecular mechanisms involved in bovine reproduction. The untreated samples contained large numbers of protein degradation products that interfered with the analysis of the neuropeptides. In the thermally stabilized samples, we were able to identify many more neuropeptides that are known to be expressed in the bovine hypothalamus. Furthermore, we have characterized a range of post-translational modifications that indicate the presence of processed intact mature neuropeptides in the stabilized tissue samples, whereas we detected many trimmed or truncated peptides resulting from post-mortem degradation in the untreated tissue samples. Altogether, using an optimized workflow, we were able to identify 140 candidate neuropeptides. We also nominate six new candidate neuropeptides derived from proSAAS, secretogranin-2 and proTRH.