Properties of a unique mutant of Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus that exhibits a partial many polyhedra and few polyhedra phenotype on extended serial passaging in suspension cell cultures

Serial passaging of wild-type Helicoverpa armigera, single-nucleocapsid (HaSNPV) in H. zea (HzAMI) illsect Cell Cultures results ill rapid selection for the few polyhedra (FP) phenotype. A unique HaSNPV mutant (ppC19) was isolated through plaque purification that exhibited a partial many polyhedra (MP) and FP phenotype. Oil serial passaging in suspension cell cultures, ppC19 produced fivefold more polyhedra than a typical FP mutant (FP8AS) but threefold less polyhedra than the wild-type virus. Most importantly, the polyhedra of ppC19 exhibited MP-like virion occlusion. Furthermore, ppC19 produced the same amount of budded virus (BV) as the FP mutant, which was fivefold higher than that of the wild-type virus. This selective advantage was likely to explain its relative stability in polyhedra production for six passages when compared with the wild-type Virus. However, subsequent passaging of ppC19 resulted in a steel) decline in both BV and polyhedra yields, which was also experienced by FP8AS and the wild-type virus Lit high passage numbers. Genomic deoxyribonueleic Licid profiling of the latter suggested that defective interfering particles (DIPS) were implicated in this phenomenon and represented another Undesirable mutation during serial passaging of HaSNPV Hence, a strategy to isolate HaSNPV Clones that exhibited MP-like polyhedra production but FP-like BV production, coupled with low multiplicities of infection during scale-up to avoid accumulation of DIPS, could prove commerically invaluable.

Complex life cycles and offspring provisioning in marine invertebrates

Offspring size can have pervasive effects throughout an organism's life history. Mothers can make either a few large or many small offspring, and the balance between these extremes is determined by the relationship between offspring size and performance. This relationship in turn is thought to be determined by the offspring's environment. Recently, it has become clear that events in one life-history stage can strongly affect performance in another. Given these strong carryover effects, we asked whether events in the larval phase can change the relationship between offspring size and performance in the adult phase. We manipulated the length of the larval period in the bryozoan Bugula neritina and then examined the relationship between offspring size and various parameters of adult performance under field conditions. We found that despite the adult stage being outplanted into identical conditions, different offspring sizes were predicted to be optimal, depending on the experience of those adults as larvae. This work highlights the fact that the strong phenotypic links between life-history stages may result in optimal offspring size being highly unpredictable for organisms with complex life cycles.

Entangled-state cycles from conditional quantum evolution

A system of cascaded qubits interacting via the one-way exchange of photons is studied. While for general operating conditions the system evolves to a superposition of Bell states (a dark state) in the long-time limit, under a particular resonance condition no steady state is reached within a finite time. We analyze the conditional quantum evolution (quantum trajectories) to characterize the asymptotic behavior under this resonance condition. A distinct bimodality is observed: for perfect qubit coupling, the system either evolves to a maximally entangled Bell state without emitting photons (the dark state) or executes a sustained entangled-state cycle-random switching between a pair of Bell states while emitting a continuous photon stream; for imperfect coupling, two entangled-state cycles coexist, between which a random selection is made from one quantum trajectory to another.

Dramatic extension of tumor latency and correction of neurobehavioral phenotype in Atm-mutant mice with a nitroxide antioxidant

Mutations in the ATM gene (mutated in ataxia telangiectasia) in both humans and mice predispose to lymphoid tumors. A defect in this gene also causes neurodegeneration in humans and a less severe neurological phenotype in mice. There is some evidence that oxidative stress contributes to these defects, suggesting that antioxidants could alleviate the phenotype. We demonstrate here that the antioxidant 5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl (CTMIO) dramatically delays the onset of thymic lymphomas in Atm(-/-) mice which is not due to an enhancement of apoptosis by CTMIO. We also show that this compound corrects neurobehavioral deficits in these mice and reduces oxidative damage to Purkinje cells. The likely mechanism of action of CTMIO is due to a reduction in oxidative stress, which is protective against both the tumor progression and the development of neurological abnormalities. These data suggest that antioxidant therapy has considerable potential in the management of ataxia telangiectasia and possibly other neurodegenerative disorders where oxidative stress is implicated. (c) 2006 Elsevier Inc. All rights reserved.

Mutant huntingtin inhibits clathrin-independent endocytosis and causes accumulation of cholesterol in vitro and in vivo.

We show that the mutant Huntington's disease (HD) protein (mhtt) specifically inhibits endocytosis in primary striatal neurons. Unexpectedly, mhtt does not inhibit clathrin-dependent endocytosis as was anticipated based on known interacting partners. Instead, inhibition occurs through a non-clathrin, caveolar-related pathway. Expression of mhtt inhibited internalization of BODIPY-lactosylceramide (LacCer), which is internalized by a caveolar-related mechanism. In contrast, endocytosis of Alexa Fluor 594-transferrin (Tfn) and epidermal growth factor, internalized through clathrin pathway, was unaffected by mhtt expression. Caveolin-1 (cav1), the major structural protein of caveolae binds cholesterol and is responsible for its trafficking inside cells. Mhtt interacts with cav-1 and caused a striking accumulation of intracellular cholesterol. Cholesterol accumulated in cultured neurons expressing mhtt in vitro and in brains of mhtt-expressing animals in vivo, and was observed after induction of mhtt expression in PC-12 cell lines. The accumulation occurred only when mhtt and cav1 were simultaneously expressed in cells. Knockdown of cav1 in mhtt-expressing neurons blocked cholesterol accumulation and restored LacCer endocytosis. Thus, mhtt and cav1 functionally interact to cause both cellular defects. These data provide the first direct link between mhtt and caveolar-related endocytosis and also suggest a possible mechanism for HD neurotoxicity where cholesterol homeostasis is perturbed.

Short root mutant of Lotus japonicus with a dramatically altered symbiotic phenotype

Legume plants carefully control the extent of nodulation in response to rhizobial infection. To examine the mechanism underlying this process we conducted a detailed analysis of the Lotus japonicus hypernodulating mutants, har1-1, 2 and 3 that define a new locus, HYPERNODULATION ABERRANT ROOT FORMATION (Har1), involved in root and symbiotic development. Mutations in the Har1 locus alter root architecture by inhibiting root elongation, diminishing root diameter and stimulating lateral root initiation. At the cellular level these developmental alterations are associated with changes in the position and duration of root cell growth and result in a premature differentiation of har1-1 mutant root. No significant differences between har1-1 mutant and wild-type plants were detected with respect to root growth responses to 1-aminocyclopropane1-carboxylic acid, the immediate precursor of ethylene, and auxin; however, cytokinin in the presence of AVG (aminoetoxyvinylglycine) was found to stimulate root elongation of the har1-1 mutant but not the wild-type. After inoculation with Mesorhizobium loti, the har1 mutant lines display an unusual hypernodulation (HNR) response, characterized by unrestricted nodulation (hypernodulation), and a concomitant drastic inhibition of root and shoot growth. These observations implicate a role for the Har1 locus in both symbiotic and non-symbiotic development of L. japonicus, and suggest that regulatory processes controlling nodule organogenesis and nodule number are integrated in an overall mechanism governing root growth and development.

Structure repair of a compacted vertisol with wet-dry cycles and crops

We hypothesized that the four rotation crops: wheat (Triticum aestivum L.), sorghum [Sorghum bicolor (L.) Merr.], lablab [Lablab purpureus (L.) Sweet] and mung bean [ Vigna radiata (L.) R. Wilczek] differ in their ability to repair soil structure. The study was conducted on a Typic Haplustert, Queensland, Australia, locally termed a Black Earth and considered a prime cropping soil. Large (0.5-m depth by 0.3-m diam.) soil cores, collected from compacted wheel furrows in an irrigated cotton (Gossypium hirsutum L.) field, were subjected to three, six, or nine wet-dry cycles that simulated local flood irrigation practices. After each cycle, soil profiles were sampled for clod bulk density, image analysis of soil structure, and evapotranspiration. Generally, all crops improved soil structure over the initial field condition but lablab and mung bean gave improvements to greater depths and more rapidly than wheat and sorghum. Mung bean and lablab caused up to a threefold increase in clod porosity in the 0.1- to 0.4-m soil layer after only three wet-dry cycles, whereas sorghum required nine wet-dry cycles to increase clod porosity in only the 0.2- to 0.3-m layer, and wheat gave no improvement even after nine wet-dry cycles. Image analysis of soil structure showed that lablab and mung bean rapidly (by three wet-dry cycles) produced smaller peds with more interconnected pore space than wheat and sorghum. By nine wet-dry cycles, sorghum achieved deep cracking of the soil but the material between the cracks remained large and dense. Evapotranspiration was double under lablab and mung bean compared with wheat and sorghum. Our results indicate greater cycles of wetting and drying under lablab and mung bean than wheat and sorghum that have led to rapid repair of soil compaction.