Reevaluation of the virulence of prototypic strain 15 of pneumonia virus of mice

Prototypic strain 15 of pneumonia virus of mice (PVM) has been described as being nonpathogenic in mice, in contrast to the mouse-passaged, highly virulent strain J3666. Previous sequence analysis also indicated that strain 15 encodes an attachment G protein that is truncated at the amino terminus, which for the amino terminally anchored protein deletes the cytoplasmic tail. However, we found that PVM strain 15 obtained from the American Type Culture Collection was highly virulent in mice and was essentially indistinguishable on that basis from strain J3666. Sequence analysis showed that this preparation of virus encodes a G protein with an intact cytoplasmic tail: the truncated predicted protein in the previous sequence appeared to be due to a single nucleotide insertion that disrupted the upstream end of the open reading frame and shifted the translational start site to the next downstream AUG. Taken together, the two studies indicate that strain 15 is an inherently virulent strain but that a nonpathogenic variant that was generated during passage in vitro and encodes a truncated G protein exists. Interestingly, the majority sequence of strain J3666 was found to encode a G protein with an extended cytoplasmic tail, suggesting that there is the potential for considerable plasticity in the cytoplasmic tail of the G protein of PVM.     

The Significance of Non-vertical Transmission of Phenotype for the Evolution of Altruism

My aim in this paper is to demonstrate that a very simple learning rule based on imitation can help to sustain altruism as a culturally transmitted pattern or behaviour among agents playing a standard prisoner’s dilemma game. The point of this demonstration is not to prove that imitation is single-handedly responsible for existing levels of altruism (a thesis that is false), nor is the point to show that imitation is an important factor in explanations for the evolution of altruism (a thesis already prominent in the existing literature). The point is to show that imitation contributes to the evolution of altruism in a particular way that is not always fairly represented by evolutionary game theory models. Specifically, the paper uses a simple model to illustrate that cultural transmission includes mechanisms that do not transmit phenotype vertically (i.e. from parent to related offspring) and that these mechanisms can promote altruism in the absence of any direct biological propensity favouring such behaviour. This is a noteworthy result because it shows that evolutionary models can be built to explicitly reflect the contribution of non-vertical transmission in our explanations for the evolution of altruism among humans and other social species.     

The fallacy of the Principle of Procreative Beneficence

The claim that we have a moral obligation, where a choice can be made, to bring to birth the 'best' child possible, has been highly controversial for a number of decades. More recently Savulescu has labelled this claim the Principle of Procreative Beneficence. It has been argued that this Principle is problematic in both its reasoning and its implications, most notably in that it places lower moral value on the disabled. Relentless criticism of this proposed moral obligation, however, has been unable, thus far, to discredit this Principle convincingly and as a result its influence shows no sign of abating. I will argue that while criticisms of the implications and detail of the reasoning behind it are well founded, they are unlikely to produce an argument that will ultimately discredit the obligation that the Principle of Procreative Beneficence represents. I believe that what is needed finally and convincingly to reveal the fallacy of this Principle is a critique of its ultimate theoretical foundation, the notion of impersonal harm. In this paper I argue that while the notion of impersonal harm is intuitively very appealing, its plausibility is based entirely on this intuitive appeal and not on sound moral reasoning. I show that there is another plausible explanation for our intuitive response and I believe that this, in conjunction with the other theoretical criticisms that I and others have levelled at this Principle, shows that the Principle of Procreative Beneficence should be rejected.     

Change of Activity of Locomotor Centers of the Locust Locusta migratoria under Effect of Increased Gravitation

The work studies effects of elevated gravitation on activity of locomotor centers in the locust Locusta migratoria L. Under effect of the increased gravity field the excitation of the motor centers that provide activity of the locus wing apparatus was shown to decrease. Analysis of the data obtained has allowed us concluding that the higher CNS centers (subesophageal ganglion) produce at least two types of excitatory (stimulatory) effects on segmental centers, one of the types affecting motor centers in the rest state, the other, in the active state. We believe that it is the impulses of the second type that are inhibited under effect of the increased radial acceleration on the organism. There is every reason to think that an important role in these processes is played by peculiar structures of the supraesophageal ganglion protocerebrum: mushroom bodies and the central complex that regulates activity of the locust segmental centers both directly and indirectly via the subesophageal ganglion.     

Influence of the fluctuations of the alignment tensor on the analysis of the structure and dynamics of proteins using residual dipolar couplings

It has been suggested that the fluctuations of the alignment tensor can affect the results of procedures for characterizing the structure and the dynamics of proteins using residual dipolar couplings. We show here that the very significant fluctuations of the steric alignment tensor caused by the dynamics of proteins can be safely ignored when they do not correlate with those of the bond vectors. A detailed analysis of these correlations in the protein ubiquitin reveals that their effects are negligible for the analysis of backbone motions within secondary structure elements, but also that they may be significant in turns, loops and side chains, especially for bond vectors that have small residual dipolar couplings. Our results suggest that methods that explicitly consider the motions of the alignment tensor will be needed to study the large-scale structural fluctuations that take place on the millisecond timescale, which are often important for the biological function of proteins, from residual dipolar coupling measurements.     

Genetic regulation of the processes of neurogenesis

Neurons proved to be a convenient experimental model for studies of regulatory properties of the genetic apparatus during development. Formation of neuronal ensembles is controlled by multiple modifier-genes at different levels. The following gene groups can be distinguished: 1) Genes that function in differentiating neurons; 2) Genes that function in other neurons; 3) Genes that function in glial cells; 4) Genes that function in surrounding tissues; 5) Genes that function at the organism level.     

Digitoxose and the existence of a glucoreceptor in the beta cells of the islets of langerhans of the rat

On the basis that digitoxin is the only drug reported up to now that stimulating insulin release per se, partially inhibits glucose stimulated insulin release, in this work the idea that the competition glucose-digitoxin may be at the level of a hypothetical glucoreceptor in the beta cells (binding of the glycoside sugar molecule) has been investigated. Our findings indicate that the integrity of the chemical structure of digitoxin is needed to exert its pharmacological action on insulin release. We also demonstrate that digitoxose inhibits glucose stimulated insulin release without inhibiting the glucose oxidation rates of the islets. The discovery of a sugar (digitoxose) that inhibitis the insulin secretory response to glucose without inhibiting glucose metabolism is a strong evidence that the action of glucose itself is blocked at the level of glucoreceptors located in the cell membrane, which appear to be the regulator sites of insulin release.     

Design and synthesis of nonpeptide mimetics of jaspamide.

Jaspamide is a novel metabolite of mixed peptide/polyketide biosynthesis that was isolated from sponges of the genus Jaspis, and that has been reported to exhibit both insecticidal and antifungal activity. We have evaluated three nonpeptide mimetic designs, and have synthesized a nonpeptide mimic of the proposed bioactive region to investigate the structure activity relationship. Structural investigations of potential mimetics, utilizing molecular modeling in conjunction with spectroscopic and crystallographic data, indicate that positioning of the critical functional groups in two mimetics corresponds closely to that observed in jaspamide, and that the flexibility of mimetic 4 approximates that of jaspamide. Initial biological evaluation suggests that lactam mimetic 4 exhibits a biological profile similar to jaspamide.     

Effect of prolactin on the secretion of milk casein: metabolism of arachidonic acid

Mammary gland fragments were incubated in the presence of prolactin and arachidonic acid which stimulate casein secretion. The effects of these stimuli in the presence of agents that influence arachidonic acid metabolism were investigated. Chloroquine, a blocker of phospholipase A2 activity, decreased prolactin but not arachidonic acid stimulation of casein secretion. Phospholipase A2 markedly stimulated casein secretion. Nordihydroguaiaretic acid (NDGA), an antioxidant that inhibits lipoxygenase, blocked the stimulating effect of prolactin and arachidonic acid. Ultrastructural studies indicated that phospholipase A2-induced stimulation of secretion was comparable to that of prolactin but that arachidonic acid-induced stimulation did not involve the same Golgi membrane modifications. These studies suggest that prolactin and phospholipase A2 stimulate secretion by a common way, and that arachidonic acid interferes with secretion by metabolic products of the lipoxygenase pathway.     

Identification of subsets of human T cells capable of enhanced transendothelial migration.

A critical step in immunologically mediated inflammation is the migration of T cells between endothelial cells of postcapillary venules and into the tissues. To determine whether specific cells are capable of transendothelial migration, T cells that had migrated through endothelial monolayers were retrieved and analyzed. To accomplish this, human umbilical vein endothelial cells (EC) were cultured to confluence on collagen gels and incubated with human T cells. T cells that were nonadherent to the EC, those that bound to the endothelium, and cells that had migrated through the endothelial monolayer and into the collagen were individually harvested and characterized. After a 4-h incubation with EC, T cells distributed themselves such that 77 +/- 2% were nonadherent, 13 +/- 2% were bound to EC, and 10 +/- 1% had migrated into the collagen. The CD4+ T cells that had migrated into the collagen were predominantly CD29bright/CD45RObright and CD45RA-. CD8+ T cells demonstrated a greater transendothelial migratory capacity than the CD4+ T cells. The migrated CD8+ T cells were mainly CD29bright but CD45RA+. Additional phenotypic analysis of the migrating cells indicated that they contained fewer cells that expressed L-selectin. Moreover the surface expression of CD7 was less dense in the T cells that had migrated than in the nonadherent T cells. Finally the T cells that migrated were not enriched for CD45RBdim T cells. Prolonging the incubation with EC to 36 h increased the number of T cells that migrated but did not alter the predominance of CD29bright T cells in the migrated population. Stimulation of EC with IL-1 or IFN-gamma also increased the number of adherent and migrating T cells, respectively, but did not alter the phenotype of the migrating cells. These results indicate that the capacity for transendothelial migration is an intrinsic ability of certain subpopulations of T cells and is related to their stage of differentiation as identified by their surface phenotype.     

Behavioural mode of action of deet: inhibition of lactic acid attraction

Using the mosquito Aedes aegypti in a novel olfactometer that measures movement towards and away from a stimulus, we could not confirm that 'deet' is a repellent of mosquitoes. In the absence of a host, deet was an attractant and in the presence of a host, it was an inhibitor of attraction. This inhibition occurred in the gaseous phase and was therefore not the result of the physical properties of deet. We determined that L-lactic acid, a component of human sweat that is an attractant to mosquitoes, is the target of this inhibition, implying that lactic acid may be a bottleneck in the behavioural cascade preceding blood-sucking.     

Analysis of gain-of-function mutants of an ATP-dependent regulator of Tn7 transposition

The bacterial transposon Tn7 is distinguished by its unusual discrimination among targets, being particularly attracted to certain target DNA and actively avoiding other DNA. Tn7 transposition is mediated by the interaction of two alternative transposon-encoded target selection proteins, TnsD and TnsE, with a common core transposition machinery composed of the transposase (TnsAB) and an ATP-dependent DNA-binding protein TnsC. No transposition is observed with wild-type TnsABC. Here, we analyze the properties of two gain-of-function TnsC mutants that allow transposition in the absence of TnsD or TnsE. We find that these TnsC mutants have altered interactions with ATP and DNA that can account for their gain-of-function phenotype. We also show that TnsC is an ATPase and that it directly interacts with the TnsAB transposase. This work provides strong support to the view that TnsC and its ATP state are central to the control of Tn7 transposition.     

Myeloperoxidase of the leukocyte of normal blood. Nature of the prosthetic group of myeloperoxidase

The absorption spectra of alkaline pyridine hemochrome of myeloperoxidase in its native, acid, and modified forms were similar to those of heme a, and the molar extinction coefficient of myeloperoxidase heme was very similar to that of heme a, assuming that myeloperoxidase contains only one heme. The anaerobic titration of myeloperoxidase with dithionite showed that one electron was consumed per molecule of the enzyme for its conversion to its reduced form. The EPR spectrum of myeloperoxidase indicated that the enzyme contains both high-spin heme and non-heme iron. Carbonyl reagents, such as borohydride, hydrazine, and benzhydrazide, reacted with myeloperoxidase, causing blue shifts in its absorption spectrum. The heme was labeled with a tritium of boro[3H]hydride, suggesting that the reagents reacted with a formyl group on the porphyrin ring of the myeloperoxidase heme. When hydrazine was added to cyanide complex I of myeloperoxidase the complex was converted to the hydrazine-enzyme compound. Myeloperoxidase reacted with bisulfite to form a compound with an absorption spectrum similar to that of cyanide complex I. Borohydride-treated myeloperoxidase formed only one cyanide complex, while the native enzyme formed two different cyanide complexes, I (Kd = 0.3 muM) and II (approximate Kd = 0.1 mM). The EPR spectrum indicated that cyanide complex I of myeloperoxidase still contained high-spin heme. The results suggested that cyanide complex I and the bisulfite compound of myeloperoxidase were adducts between the nucleophilic reagents and the formyl group of myeloperoxidase heme. Based on these results, we concluded that one of the two iron atoms in a myeloperoxidase molecule exists in a formyl-heme moiety similar to heme a and the other exists as a non-heme iron.     

Role of SNX16 in the dynamics of tubulo-cisternal membrane domains of late endosomes

In this paper, we report that the PX domain-containing protein SNX16, a member of the sorting nexin family, is associated with late endosome membranes. We find that SNX16 is selectively enriched on tubulo-cisternal elements of this membrane system, whose highly dynamic properties and formation depend on intact microtubules. By contrast, SNX16 was not found on vacuolar elements that typically contain LBPA, and thus presumably correspond to multivesicular endosomes. We conclude that SNX16, together with its partner phosphoinositide, define a highly dynamic subset of late endosomal membranes, supporting the notion that late endosomes are organized in distinct morphological and functional regions. Our data also indicate that SNX16 is involved in tubule formation and cholesterol transport as well as trafficking of the tetraspanin CD81, suggesting that the protein plays a role in the regulation of late endosome membrane dynamics.     

A study of the effect of radium upon the eggs of Ascaris megalocephala univalens

Conclusions My observations support the conclusions ofPerthes andHertwig that the achromatic figure appears perfectly normal; that the first segmentation divisions are regular; and that irregularities enter sooner or later which cause the death of the embryo. They further support the conclusions ofHertwig that the effect of the radium manifests itself in the first segmentation division and that the chromosomes are broken up into irregular masses and granules. In addition to these, I find that in the first segmentation division, the enlarged masses of chromatin which are similar to the cast off ends in the somatic cells of normal segmentation, may or may not take part in nuclear reconstruction and the succeeding division; that the chromatin of the first segmentation division is more greatly disturbed than in the divisions which follow. More important, however, than these is the fact that the chromatin of the sex and somatic cells in the second and third segmentation divisions behaves differently. That is, while the chromosomes of both cells break up, the fragments in the sex cells are generally larger.     

Biorisk assessment of natural science laboratories of Bicol University College of Science,Philippines

A biorisk assessment of natural science laboratories in Bicol University was conducted as an initial step towards improvement of laboratories and contributing to a culture of safety in the university. Survey among laboratory workers and ocular inspection of natural science labs was done. Results showed that gaps exist in the safety knowledge and practices of laboratory workers. Microbial assets pose the lowest risk, while equipment and the use of chemicals in biological assays pose the highest risk. The likelihood that such events will occur ranges from low to moderate while consequences range from moderate to high. The research recommends that a policy on biological safety be formulated and be integrated in the overall safety guidelines of the university, that existing guidelines and SOPs be improved and that their implementation be monitored, to introduce a course for undergraduates that will tackle the basics of safety and security in the laboratory, and that the equipment and physical design be improved to reduce the risks to acceptable levels.     

Inheritance of glutenin protein subunits of wheat

Summary The inheritance of the high-molecular-weight (HMW) glutenin protein subunits in hexaploid wheat has been investigated by using sodium dodecyl sulphate-polyacrylamide gel electrophoresis to examine the segregation of these subunits in 496 test-cross seeds. The parents of the f₁ hybrid were chosen so that the test-cross seeds segregated for all the HMW glutenin bands. Two glutenin subunits from one parent, believed to be controlled by genes on chromosome 1D, segregated as alternatives to two glutenin subunits from the other parent, a result that supports the assumption that these subunits are controlled by allelic genes at each of two loci that are very closely linked. Similar results were obtained for glutenin subunits believed to be controlled by chromosome IB, which suggests that these subunits are controlled also by allelic genes at each of two loci that are very closely linked. A single glutenin subunit band, believed to be controlled by chromosome 1A, segregated as an alternative to a single glutenin band from the other parent, except that one seed did not possess either band. It was concluded that these bands are controlled either by allelic genes or by nonallelic genes that are very closely linked.     

Mode of inhibitory action of Deltalac-acetogenins, a new class of inhibitors of bovine heart mitochondrial complex I

We have revealed that Deltalac-acetogenins, a new class of inhibitors of bovine heart mitochondrial complex I (NADH-ubiquinone oxidoreductase), act differently from ordinary inhibitors such as rotenone and piericidin A [Ichimaru et al. (2005) Biochemistry 44, 816-825]. Since a detailed study of these unique inhibitors might provide new insight into the terminal electron transfer step of the enzyme, we further characterized their inhibitory action using the most potent Deltalac-acetogenin derivative (compound 1). Unlike ordinary complex I inhibitors, 1 had a dose-response curve for inhibition of the reduction of exogenous short-chain ubiquinones that was difficult to explain with a simple bimolecular association model. The inhibitory effect of 1 on ubiquinol-NAD(+) oxidoreductase activity (reverse electron transfer) was much weaker than that on NADH oxidase activity (forward electron transfer), indicating a direction-specific effect. These results suggest that the binding site of 1 is not identical to that of ubiquinone and the binding of 1 to the enzyme secondarily (or indirectly) disturbs the redox reaction of ubiquinone. Using endogenous and exogenous ubiquinone as an electron acceptor of complex I, we investigated the effect of 1 in combination with different ordinary inhibitors on the superoxide production from the enzyme. The results indicated that the level of superoxide production induced by 1 is significantly lower than that induced by ordinary inhibitors probably because of fewer electron leaks from the ubisemiquinone radical to molecular oxygen and that the site of inhibition by 1 is downstream of that by ordinary inhibitors. The unique inhibitory action of hydrophobic Deltalac-acetogenins may be closely associated with the dynamic function of the membrane domain of complex I.