Animal rights protests build

Opposition to animal experiments in Britain appears to be extending beyond the labs to other businesses supplying them. Nigel Williams reports.     

Body build structure of neonates

The paper presents anthropometric data on 292 healthy neonates delivered of normal births at the Women's Hospital of Tartu University (150 boys and 142 girls). The parameters of the neonates' physical development measured included height, weight, sitting height, length of sternum and abdomen, shoulder width, upper and lower width and depth of thorax, width and depth of abdomen, D. cristarum, D. trochanterica, pelvic depth, 12 circumferences, foot length and two skinfolds (on abdomen and back). The mean weight of a neonate was 3620.5 g±448.7 g (minimum 2400 g and maximum 4854 g). Boys were somewhat heavier than girls (3684.7 g and 3551.3 g respectively). The average height of the infants was 49.9 cm±1.9 cm (minimum 44 cm and maximum 54.5 cm). Correlation analysis of the characteristics showed that body structure is a system of wellcorrelated anthropometric measurements where the leading role belongs to height and weight. The changes in the relation between height and weight (height-weight classification in 3×3SD classes) cause systemic changes in other measurements. Therefore, in further micropaediatric and clinical research, the height-weight classification could be used as the primary model of the body as a whole.     

To build an enzyme....

The structural components that lead to enzyme function are discussed for one simple enzyme-catalysed reaction: that mediated by triosephosphate isomerase. First, the recognition and binding of the substrates' phospho group is seen to involve four main-chain-NH-hydrogen bonds, two of which are positioned at the positive end of a short alpha-helix aimed precisely at the phospho group and interact with the three peripheral phospho group oxygens. Second, the chemical steps (of substrate enolization) are shown to require both base and general acid catalysis. The identity and the positioning of the base, a carboxylate group, nicely fulfils the expectations both of mechanistic economy and of stereoelectronics. The identity of the general acid is shown by Fourier transform infrared and by 15N nuclear magnetic resonance (NMR) to be a neutral imidazole group, lying between the two substrate oxygens. The positioning of the ring is ideal, but its protonation state is unexpected. Thus the pKa of this histidine side-chain is less than 4.5, lowered from 6.5 (the value in the denatured protein) by its position at the positive end of another well-aimed alpha-helix. Third, the need for enzymes to provide kinetic barriers to the loss of reaction intermediates from the active site is emphasized. Triosephosphate isomerase achieves this sequestration of the reaction intermediate by using a flexible loop of the protein, and thus improves the efficiency of the catalysed transformation.     

How to build a paraspeckle

Noncoding RNAs have recently been identified as essential components of the nuclear suborganelles called paraspeckles. This finding will facilitate our understanding of the molecular dynamics and physiological role of these enigmatic macromolecular structures.     

How to build a mammalian super-predator

Questions surrounding the biology of large fossil predators that differ markedly from living forms have long intrigued palaeobiologists. Among such taxa few have excited more interest than sabertooth cats, whose distinctive hypertrophied canines are suggestive of killing behaviors and feeding ecologies that may have departed widely from those of extant carnivores. Moreover, considerable variation among sabertooth species is further suggestive of intriguing differences within the group. Behavior and ecology in another large, extinct mammalian carnivore, the Australian marsupial lion (Thylacoleo carnifex), has also proven contentious. In this study, we assemble a wide range of cranio-dental and postcranial indices in a dataset including machairodont sabertooths, T. carnifex and an extensive sample of extant taxa in order to examine the palaeobiology of these charismatic fossil carnivores. Results of multivariate analyses point to significant relationships between behavior and overall body proportions in extant mammalian carnivores. Postcranial morphologies of two American dirk-tooth species of sabertooth (Smilodon) depart greatly from those of living felids and group most closely with bears among living placentals. Scimitar-tooth species of Homotherium and Machairodus cluster with modern pantherine cats. The marsupial lion groups with Smilodon. If these latter two phylogenetically disparate clades do represent a specialized, robust ecomorph adapted to predation on large prey, then it is a body plan that might be effectively identified on the basis of a handful of ‘bear-like’ postcranial features in combination with a more typically ‘felid-like’ carnassialization of the cheektooth row.     

How to build a grid cell

Neurons in the medial entorhinal cortex fire action potentials at regular spatial intervals, creating a striking grid-like pattern of spike rates spanning the whole environment of a navigating animal. This remarkable spatial code may represent a neural map for path integration. Recent advances using patch-clamp recordings from entorhinal cortex neurons in vitro and in vivo have revealed how the microcircuitry in the medial entorhinal cortex may contribute to grid cell firing patterns, and how grid cells may transform synaptic inputs into spike output during firing field crossings. These new findings provide key insights into the ingredients necessary to build a grid cell.     

How to build a DNA unwinding machine

In this issue of Structure, He and colleagues present the crystal structure of the phage T4 Dda helicase bound to DNA, providing new insights into how this protein efficiently couples single-stranded DNA translocation to DNA strand separation.