Can telomerase be put in its place?

The Cajal body is an intriguing nuclear structure present in a great variety of plant, animal, and some fungal cells. Recent work on the ribonucleoprotein enzyme telomerase has indicated an unanticipated degree of intranuclear dynamics of both its RNA and protein subunits. In this issue, Jady et al. place the Cajal body on the intranuclear traffic route of telomerase RNA (Jady et al., 2004).     

DoesAgapetus fuscipes cultivate algae in its case?

The presence of algae within the cases ofAgapetus fuscipes was investigated. Cases recognised as dirty or clean with the naked eye had more and less algal growth, respectively. Larvae in the former survived significantly longer when starved in the laboratory. It is suggested that the presence of algae within the cases would be of ecological advantage during periods of flood.     

“Photosynthetica” in its Seventh Five-Year Period

Editorial Introduction

Photosynthetica in its Seventh Five-Year Period     

Quorum-sensing system in Acidithiobacillus ferrooxidans involved in its resistance to Cu²⁺

Aims: The purpose of this study was to search for the relationship between quorum sensing (QS) and Cu²⁺ resistance in Acidithiobacillus ferrooxidans. Methods and Results: Resistance to Cu²⁺ of A. ferrooxidans significantly decreased with the treatment dose of a synthetic QS blocker (5Z)‐4‐bromo‐5‐(bromomethylene)‐2(5H)‐furanone (FUR). Relative differences in expression of the QS genes afeI, afeR and Cu²⁺ resistance‐associated genes afe0329, afe0454 were examined in the presence of Cu²⁺ and/or FUR compound. The expression of QS genes afeI and afeR increased significantly with 50 mmol l^?1 Cu²⁺ in the culture, while for samples treated with both 50 mmol l^?1 Cu²⁺ and 0·01 μg ml^?1 FUR compound, they showed little changes compared with control, and the expression of afe0329 and afe0454 genes increased slightly either. These results showed that QS system was positively related to the mechanism of Cu²⁺ resistance. Conclusions: QS system in A. ferrooxidans involved in its resistance to Cu^2+. Significance and Impact of the Study: The mechanisms of Cu²⁺ resistance in A. ferrooxidans could be revealed on a population level rather than on a single‐cell level. Our work also provides useful data for further selection of A. ferrooxidans strains with suitable Cu²⁺ resistance that could probably increase the bioleaching efficiency.     

The “polarizing inducer” in hydra: A reexamination of its properties and its origin

Summary In order to prove the gradient hypothesis an attempt was made to isolate and accumulate the polarizing inducer present in homogenates of hydra and assumed to be a neurosecretory product. By means of gel chromatography two fractions were obtained which brought about the development of supernumary apical structures (tentacles and hypostomes) thus exhibiting the symptoms attributed to this polarizing agent: a low molecular fraction with only modest effectiveness and a main fraction with strong animalizing ability. Increasing the concentration affected only the quantity but not the qualitative properties of the structures produced, a result inconsistent with the postulate of the gradient hypothesis. By analysing the chemical and biological nature of the main agent and by applying pure isolated toxins compelling evidence is given that the inducer in question is nothing but a component of the nematocyst toxins. This component, being heat-stable and trypsin-sensitive, elicites its animalizing effect in unspecific means by disturbing the normal pattern of morphallactic events. A side effect with interest in respect of graded tissue properties could be recorded: by the influence of the relevant toxin, growing together of regenerating animals occurs whereby predominantly apical primordia fuse with apical primordia, thus forming stable parabioses. This observation may indicate the significance of surface bound, contact establishing components in polar differentiation.

---

Zusammenfassung Zur Prüfung der entwicklungsphysiologischen Gradiententheorie wird der Versuch unternommen, den polarisierenden Induktor zu isolieren und anzureichern, der in Homogenaten von Hydra zugegen ist und als neurosekretorisches Produkt angesehen wird. Die Gelchromatographie wäßriger Extrakte liefert 2 Fraktionen, welche die Entwicklung überzähliger apikaler Strukturen (Tentakel und Mundkegel) hervorrufen: eine niedermolekulare Fraktion mit nur mäßiger Wirksamkeit und eine Hauptfraktion im mittelmolekularen Bereich mit starker animalisierender Kapazität. Entgegen dem Postulat der Gradiententheorie besteht keine Korrelation zwischen der applizierten Konzentration und der Qualität ausgelöster Formbildungen. Nur die Anzahl überzähliger Strukturen ist dosisabhängig. Die Analyse der biologischen und chemischen Eigenschaften der Hauptfraktion bringt den Hinweis, daß das polarisierende Agens eine Hitze-stabile, Trypsin-sensitive Komponenteder Nesselgifte ist, die ihre animalisierende Wirkung in unspezifischer Weise zeitigt. Die Applikation isolierter, reiner Nesselgifte erhärtet diese Vermutung zum klaren Beweis. Ein Nebeneffekt des relevanten Gifts legt graduierte Gewebseigenschaften offen: Unter seinem Einfluß verwachsen die Testpolypen, sowie sie in Kontakt zueinander kommen. Hierbei verbinden sich vorzugsweise apikale Primordien mit apikalen Primordien, um stabile Parabiosen zu bilden. Diese Beobachtung mag die Bedeutung Kontakt-vermittelnder Oberflächenstrukturen für das polare Differenzierungsgeschehen anzeigen.

---

---

Supported by Deutsche Forschungsgemeinschaft.     

D-Chiro-Inositol – Its Functional Role in Insulin Action and its Deficit in Insulin Resistance

In this review we discuss the biological significance of D-chiro-inositol, originally discovered as a component of a putative mediator of intracellular insulin action, where as a putative mediator, it accelerates the dephosphorylation of glycogen synthase and pyruvate dehydrogenase, rate limiting enzymes of non-oxidative and oxidative glucose disposal.Early studies demonstrated a linear relationship between its decreased urinary excretion and the degree of insulin resistance present. When tissue contents, including muscle, of type 2 diabetic subjects were assayed, they demonstrated a more general body deficiency. Administration of D-chiro-inositol to diabetic rats, Rhesus monkeys and now to humans accelerated glucose disposal and sensitized insulin action.A defect in vivo in the epimerization of myoinositol to chiro-inositol in insulin sensitive tissues of the GK type 2 diabetic rat has been elucidated. Thus, administered D-chiro-inositol may act to bypass a defective normal epimerization of myo-inositol to D-chiro-inositol associated with insulin resistance and act to at least partially restore insulin sensitivity and glucose disposal.     

WHO in retreat: is it losing its influence?

WHO says it has three main functions: to set normative standards; to provide technical advice and assistance on medical matters; and to advocate changes in health policy. During its 46 year history the first two functions have been a constant and uncontroversial backbone through which WHO has earned its reputation for scientific excellence. The third function, advocacy, came to the fore with the launch of Health for All in 1977, after which WHO took a key role in influencing international health policy. WHO''s friends and critics alike now say that the organisation is losing its influence and retreating into its technical and biomedical shell. This article maps the changes in WHO''s approach over the past 46 years and considers whether fears about its loss of influence are justified.     

Zinc downregulates HIF-1α and inhibits its activity in tumor cells in vitro and in vivo

Background

Hypoxia inducible factor-1α (HIF-1α) is responsible for the majority of HIF-1-induced gene expression changes under hypoxia and for the “angiogenic switch” during tumor progression. HIF-1α is often upregulated in tumors leading to more aggressive tumor growth and chemoresistance, therefore representing an important target for antitumor intervention. We previously reported that zinc downregulated HIF-1α levels. Here, we evaluated the molecular mechanisms of zinc-induced HIF-1α downregulation and whether zinc affected HIF-1α also in vivo.

Methodology/Principal Findings

Here we report that zinc downregulated HIF-1α protein levels in human prostate cancer and glioblastoma cells under hypoxia, whether induced or constitutive. Investigations into the molecular mechanisms showed that zinc induced HIF-1α proteasomal degradation that was prevented by treatment with proteasomal inhibitor MG132. HIF-1α downregulation induced by zinc was ineffective in human RCC4 VHL-null renal carcinoma cell line; likewise, the HIF-1αP402/P564A mutant was resistant to zinc treatment. Similarly to HIF-1α, zinc downregulated also hypoxia-induced HIF-2α whereas the HIF-1β subunit remained unchanged. Zinc inhibited HIF-1α recruitment onto VEGF promoter and the zinc-induced suppression of HIF-1-dependent activation of VEGF correlated with reduction of glioblastoma and prostate cancer cell invasiveness in vitro. Finally, zinc administration downregulated HIF-1α levels in vivo, by bioluminescence imaging, and suppressed intratumoral VEGF expression.

Conclusions/Significance

These findings, by demonstrating that zinc induces HIF-1α proteasomal degradation, indicate that zinc could be useful as an inhibitor of HIF-1α in human tumors to repress important pathways involved in tumor progression, such as those induced by VEGF, MDR1, and Bcl2 target genes, and hopefully potentiate the anticancer therapies.     

Location of β-amylase sequences in wheat and its relatives

Summary A -amylase cDNA clone isolated from barley has been used to locate -amylase encoding sequences on wheat, rye, and Aegilops umbellulata chromosomes by hybridisation to restriction endonuclease digested DNA obtained from wheat aneuploid and wheat-alien addition lines. Structural genes were identified on homoeologous group 4 and 5 chromosomes, confirming the results of isozyme studies. In addition, a further set of structural genes was found on homoeologous group 2 chromosomes. It is proposed that there are two homoeoallelic series, -Amy-1 on group 4 or 5 chromosomes, and -Amy-2 on group 2 chromosomes. Evidence is presented that each locus contains one or two -amylase structural genes, and it is suggested that the large number of isozymes seen upon IEF are due to post-translational modifications.     

Multiple sites in αB-crystallin modulate its interactions with desmin filaments assembled in vitro

The β3- and β8-strands and C-terminal residues 155-165 of αB-crystallin were identified by pin arrays as interaction sites for various client proteins including the intermediate filament protein desmin. Here we present data using 5 well-characterised αB-crystallin protein constructs with substituted β3- and β8-strands and with the C-terminal residues 155-165 deleted to demonstrate the importance of these sequences to the interaction of αB-crystallin with desmin filaments. We used electron microscopy of negatively stained samples to visualize increased interactions followed by sedimentation assays to quantify our observations. A low-speed sedimentation assay measured the ability of αB-crystallin to prevent the self-association of desmin filaments. A high-speed sedimentation assay measured αB-crystallin cosedimentation with desmin filaments. Swapping the β8-strand of αB-crystallin or deleting residues 155-165 increased the cosedimentation of αB-crystallin with desmin filaments, but this coincided with increased filament-filament interactions. In contrast, substitution of the β3-strand with the equivalent αA-crystallin sequences improved the ability of αB-crystallin to prevent desmin filament-filament interactions with no significant change in its cosedimentation properties. These data suggest that all three sequences (β3-strand, β8-strand and C-terminal residues 155-165) contribute to the interaction of αB-crystallin with desmin filaments. The data also suggest that the cosedimentation of αB-crystallin with desmin filaments does not necessarily correlate with preventing desmin filament-filament interactions. This important observation is relevant not only to the formation of the protein aggregates that contain both desmin and αB-crystallin and typify desmin related myopathies, but also to the interaction of αB-crystallin with other filamentous protein polymers.     

β-adrenergic modulation of in vivo long-term potentiation in area CA1 and its role in spatial learning in rats

The hippocampus plays a key role in declarative learning and memory [1]. Hippocampal long-term potentiation (LTP) is a type of synaptic plasticity that has been widely studied as a syn-aptic mechanism underlying learning and memory[27]. It has been reported that in vitro LTP in area CA1 is subjected to b-adrenergic modulation. For example, the theta-pulse stimulation (510 Hz), a neutral frequency not modifying synaptic strength, can elicit a robust LTP in area CA1 in slice when the b-adr…     

Abscisic acid in soils: What is its function and which factors and mechanisms influence its concentration?

Abscisic acid (ABA) was detected in aqueous extracts of a range of different soils, beneath a range of crops, pasture and forest species. Assuming that all the ABA is dissolved in the soil solution concentrations ranged from 0.6–2.8 nM. This is in the range which computer simulations predict is required in soils in order to prevent ABA release from the root hair zones of plant roots. The concentration of ABA in the soil solution was highest in acid soils and in soils with reduced moisture, and was lowest in moist, neutral and moderately alkaline soils. ABA in the soil solution of maize fields increased during the vegetative period. After incubation in soil for 72 h, radioactive ABA was degraded by 30–40%. Tetcyclacis, an inhibitor of the oxidative breakdown of ABA, completely prevented the degradation of ABA in the soil solution. Acid conditions and high salt concentrations significantly retarded ABA breakdown.     

Elastin calcification in in vitro models and its prevention by MGP’s N-terminal peptide

Medial calcification has been associated with diabetes, chronic kidney disease, and genetic disorders like pseudoxanthoma elasticum. Recently, we showed that genetic reduction of arterial elastin content reduces the severity of medial calcification in matrix Gla protein (MGP)-deficient and Eln haploinsufficient Mgp?/?;Eln+/? mice. This study suggests that there might be a direct effect of elastin amount on medial calcification. We studied this using novel in vitro systems, which are based on elastin or elastin-like polypeptides. We first examined the mineral deposition properties of a transfected pigmented epithelial cell line that expresses elastin and other elastic lamina proteins. When grown in inorganic phosphate-supplemented medium, these cells deposited calcium phosphate minerals, which could be prevented by an N’-terminal peptide of MGP (m3pS) carrying phosphorylated serine residues. We next confirmed these findings using a cell-free elastin-like polypeptide (ELP₃) scaffold, where the peptide prevented mineral maturation. Overall, this work describes a novel cell culture model for elastocalcinosis and examines the inhibition of mineral deposition by the m3pS peptide in this and a cell-free elastin-based scaffold. Our study provides strong evidence suggesting the critical functional roles of MGP’s phosphorylated serine residues in the prevention of elastin calcification and proposes a possible mechanism of their action.     

NO 2 − Efflux and its regulation in cyanobacterium Nostoc MAC

NO ₂ ^– efflux and its regulation have been studied in the cyanobacterium Nostoc MAC. 3-(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU), carbonyl cyanide-m-chlorophenyl hydrazone (CCCP), sodium azide, p-chloromercuribenzoate (PCMB), and dicyclohexylcarbodiimide (DCCD), a specific inhibitor of bacterial ATPase, inhibited the NO ₂ ^– efflux activity singificantly. No NO ₂ ^– efflux activity was observed under dark-aerobic as well as under dark-anaerobic conditions; however, the addition of ATP resulted in NO ₂ ^– efflux even under dark-aerobic condition. Maximum NO ₂ ^– efflux activity was observed when NO ₃ ^– served as the sole nitrogen source. However, NH ₄ ⁺ ions inhibited the NO ₂ ^– efflux activity when both NO ₃ ^– and NH ₄ ⁺ wer simulatneously available to the cells. The NO ₂ ^– efflux was freed from NH ₄ ⁺ repression by l-methionine-dl-sulfoximine (MSX), an irreversible inhibitor of glutamine synthetase (GS). Chloramphenicol, a protein synthesis inhibitor, inhibited the derepression of NO ₂ ^– efflux system when NH ₄ ⁺ -incubated cells were transferred to NO ₃ ^– medium. Tungstate-treated cells lacking functional NO ₃ ^– reductase but having NO ₃ ^– uptake activity also lacked NO ₂ ^– efflux activity. These results suggest that (i) NO ₂ ^– efflux in Nostoc MAC is NO ₃ ^– dependent and an energy-dependent process that can be regulated at the levels of NO ₃ ^– uptake and NO ₃ ^– reductase; (ii) NO ₂ ^– efflux system is NH ₄ ⁺ repressible; however, the product of NH ₄ ⁺ assimilation via GS is being required for repression to occur; (iii) de novo protein synthesis is required for derepression of the NO ₂ ^– efflux system; and (iv) the catalytic activity of NO ₂ ^– reductase also seems to play an important role in the regulation of NO ₂ ^– efflux system.     

Corneal collagen—its role in maintaining corneal shape and transparency

Corneal collagen has a number of properties that allow it to fulfil its role as the main structural component within the tissue. Fibrils are narrow, uniform in diameter and precisely organised. These properties are vital to maintain transparency and to provide the biomechanical prerequisites necessary to sustain shape and provide strength. This review describes the structure and arrangement of corneal collagen from the nanoscopic to the macroscopic level, and how this relates to the maintenance of the form and transparency of the cornea.