Is the shoot a root with a view?

Recently, it has been shown that the same sets of genes act in both root and shoot to regulate cell fate and patterning. One gene cassette regulates epidermal cell fate, another cassette regulates ground tissue derived cell fate and organization. Ectopic expression and laser ablation have been used to probe the mechanisms by which these genes perform their tissue and organ-specific functions.     

The common guava—a neglected fruit with a promising future

This tropical American fruit, cultivated in Florida and elsewhere around the world, was used, because of its high vitamin-C content, to fortify military food rations in World War II.     

Cancer: a single disease with a multitude of manifestions?

The relationships of critical nutrients such as plant phenolics, vitamins, minerals and lipids are considered with respect to the incidence of a variety of cancers, and analyzed in terms of how these nutrient deficiencies alter immune function, DNA integrity and cell proliferation. With a significant correlation found between cancer and these nutrient deficiencies, the hypothesis is presented here that nutrition could provide a unifying perception of cancer and recast it as a single disease. This further suggests that a coordinated administration of specific, critical nutrients to cancer patients could lead to the reversal of the disease. It is also proposed that the concurrent presence of a variety of nutritional deficiencies in cancer patients requires a multilevel, systemic approach to this disease as opposed to the single active therapeutic agent approach that is the cornerstone of contemporary research and pharmacology.     

Cerebro-Oculo-Facio-Skeletal Syndrome with a Nucleotide Excision–Repair Defect and a Mutated XPD Gene, with Prenatal Diagnosis in a Triplet Pregnancy

Cerebro-oculo-facio-skeletal (COFS) syndrome is a recessively inherited rapidly progressive neurologic disorder leading to brain atrophy, with calcifications, cataracts, microcornea, optic atrophy, progressive joint contractures, and growth failure. Cockayne syndrome (CS) is a recessively inherited neurodegenerative disorder characterized by low to normal birth weight, growth failure, brain dysmyelination with calcium deposits, cutaneous photosensitivity, pigmentary retinopathy and/or cataracts, and sensorineural hearing loss. Cultured CS cells are hypersensitive to UV radiation, because of impaired nucleotide-excision repair (NER) of UV-induced damage in actively transcribed DNA, whereas global genome NER is unaffected. The abnormalities in CS are caused by mutated CSA or CSB genes. Another class of patients with CS symptoms have mutations in the XPB, XPD, or XPG genes, which result in UV hypersensitivity as well as defective global NER; such patients may concurrently have clinical features of another NER syndrome, xeroderma pigmentosum (XP). Clinically observed similarities between COFS syndrome and CS have been followed by discoveries of cases of COFS syndrome that are associated with mutations in the XPG and CSB genes. Here we report the first involvement of the XPD gene in a new case of UV-sensitive COFS syndrome, with heterozygous substitutions-a R616W null mutation (previously seen in patients in XP complementation group D) and a unique D681N mutation-demonstrating that a third gene can be involved in COFS syndrome. We propose that COFS syndrome be included within the already known spectrum of NER disorders: XP, CS, and trichothiodystrophy. We predict that future patients with COFS syndrome will be found to have mutations in the CSA or XPB genes, and we document successful use of DNA repair for prenatal diagnosis in triplet and singleton pregnancies at risk for COFS syndrome. This result strongly underlines the need for screening of patients with COFS syndrome, for either UV sensitivity or DNA-repair abnormalities.     

Fecal metabolite of a gnotobiotic mouse transplanted with gut microbiota from a patient with Alzheimer’s disease

ABSTRACT

Studies of Alzheimer’s disease are based on model mice that have been altered by transgenesis and other techniques to elicit pathogenesis. However, changes in the gut microbiota were recently suggested to diminish cognitive function in patients, as well as in model mice. Accordingly, we have created model mice of the human gut microbiota by transplanting germ-free C57BL/6N mice with fecal samples from a healthy volunteer and from an affected patient. These humanized mice were stably colonized and reproduced the bacterial diversity in donors. Remarkably, performance on Object Location Test and Object Recognition Test was significantly reduced in the latter than in the former at 55 weeks of age, suggesting that gut microbiota transplanted from an affected patient affects mouse behavior. In addition, metabolites related to the nervous system, including γ-aminobutyrate, taurine, and valine, were significantly less abundant in the feces of mice transplanted with microbiota from the affected patient.     

Analysis of a competitive prey–predator system with a prey refuge

Gauss's competitive exclusive principle states that two competing species having analogous environment cannot usually occupy the same space at a time but in order to exploit their common environment in a different manner, they can co-exist only when they are active in different times. On the other hand, several studies on predators in various natural and laboratory situations have shown that competitive coexistence can result from predation in a way by resisting any one prey species from becoming sufficiently abundant to outcompete other species such that the predator makes the coexistence possible. It has also been shown that the use of refuges by a fraction of the prey population exerts a stabilizing effect in the interacting population dynamics. Further, the field surveys in the Sundarban mangrove ecosystem reveal that two detritivorous fishes, viz. Liza parsia and Liza tade (prey population) coexist in nature with the presence of the predator fish population, viz. Lates calcarifer by using refuges.     

X-linked mental retardation with Marfanoid habitus: a changing phenotype with age?

In this report, we present two further examples of X-linked mental retardation with Marfanoid habitus. Follow-up data on these two patients reveal that the clinical diagnosis of this syndrome is extremely difficult, if not impossible before puberty, as the Marfanoid habitus only becomes strikingly evident during adolescence.     

Chlorophyll-a determination with ethanol – a critical test

Chlorophyll-a content is widely used as an indicator of the quality of freshwater bodies. Quantification of chlorophyll-a is a routine procedure in the test laboratories of water works, and in research laboratories. Although attempts have been made to standardise the measurement procedure, there are nonetheless many procedures currently in use. This work is focused on a careful re-examination of the ISO: 10260, 1992 standard, which prescribes 90% (v/v) ethanol for chlorophyll extraction and measurement. Chlorophyll contents of cultures of the cyanobacterium Synechococcus elongatus Nägeli and the chlorophyte Scenedesmus acutus Meyen were determined by means of a series of concentrations of ethanol/water mixtures which were employed as extracting agents – the water content was gradually decreased from 20 to 0%. The extraction procedure was verified by measuring the amount of retained water after using both water and oil pumps for filtering the samples. The spectroscopic effects of the presence of water were studied and the molecular background of these spectral phenomena is discussed. The extraction yields obtained with 90% ethanol were compared to those obtained with methanol and acetone. On the basis of the calculated error level, improvements to the ISO: 10260, 1992 standard method have been suggested.     

Selective recognition of alkanoates by a β-cyclodextrin flexibly capped with a chromophore

The association between 6-deoxy-6-(p-hydroxy-m-nitrophenacylthio)-β-cyclodextrin 1 and sodium n-alkanoate, sodium 2,2-dimethylpropionate, or sodium 3,3-dimethylbutyrate was investigated. Host-guest association was measured by means of electronic spectroscopy and circular dichroism spectroscopy and ascertained to be 1:1. The inclusion of 2,2-dimethylpropionate or butanoate marginally affected the circular dichroism spectrum of 1. The inclusion of 3,3-dimethylbutyrate, hexanoate, octanoate, decanoate, or dodecanoate, however, dramatically affected the spectrum of 1. The plots of molecular ellipticities of the inclusion complexes against the carbon number of the n-alkanoates were sigmoid. From these observations, the effective size of the guest molecule to push the chromophore in the cavity to the capping position was estimated. From the similarity of the spectrum of the octanoate-1 complex to that of 1-adamantanecarboxylate-1 complex, the carbon chain of octanoate appears to be folded in the cavity of the cyclodextrin.     

Solution structure of a novel α-conotoxin with a distinctive loop spacing pattern

α-Pharmacological conotoxins are among the most selective ligands of nicotinic acetylcholine receptors with typical cysteine frameworks. They are characterized by the intercysteine loop and classified into various subfamilies, such as α3/5 and α4/7 conotoxins. A novel α-conotoxin, Pu14a (DCPPHPVPGMHKCVCLKTC), with a distinct loop spacing pattern between cysteines was reported recently. Pu14a belongs to the Cys framework 14 (-C-C-C-C) family containing four proline residues in the loop 1 region. Similar to another framework 14 conotoxin Lt14a (MCPPLCKPSCTNC-NH2), Pu14a has C1-C3/C2-C4 disulfide linkage, and can inhibit some subtypes of nicotinic acetylcholine receptors. In this study, the solution structure of Pu14a was investigated using 1H nuclear magnetic resonance spectroscopy to understand the structure-activity relationship of this conotoxin. 20 converged structures of this conopeptide, with RMSD value of 0.77 ?, were obtained based on distance constraints, dihedral angles and disulfide bond constraints. The three-dimensional structure of Pu14a showed remarkable difference from typical α-conotoxins because of a large intercysteine loop between C2 and C13, as well as a 3(10)-helix near the C-terminal. Furthermore, four proline residues in Pu14a adopted the trans conformation that may correlate with the large loop configuration and the biological activity of this conopeptide. The distinct structural characteristics of Pu14a will be very useful for studying the structure-activity relationship of α-conotoxins.     

How Does a Voltage Sensor Interact with a Lipid Bilayer? Simulations of a Potassium Channel Domain

The nature of voltage sensing by voltage-activated ion channels is a key problem in membrane protein structural biology. The way in which the voltage-sensor (VS) domain interacts with its membrane environment remains unclear. In particular, the known structures of Kv channels do not readily explain how a positively charged S4 helix is able to stably span a lipid bilayer. Extended (2 x 50 ns) molecular dynamics simulations of the high-resolution structure of the isolated VS domain from the archaebacterial potassium channel KvAP, embedded in zwitterionic and in anionic lipid bilayers, have been used to explore VS/lipid interactions at atomic resolution. The simulations reveal penetration of water into the center of the VS and bilayer. Furthermore, there is significant local deformation of the lipid bilayer by interactions between lipid phosphate groups and arginine side chains of S4. As a consequence of this, the electrostatic field is "focused" across the center of the bilayer.     

Functionalization of a protein surface with per-O-methylated β-cyclodextrin

Per-O-methylated β-cyclodextrin (CD) bearing an iodoacetamide group at the 6-position was synthesized to functionalize protein surfaces. Bovine serum albumin (BSA) was quantitatively modified with the CD derivative by the S(N) 2 reaction of iodoacetamide with a cysteine residue (Cys34) on the BSA surface. The resultant CD-functionalized BSA (BSA-CD) spontaneously dimerized upon addition of an anionic tetraarylporphyrin (TPPS) through the supramolecular 1:2 complexation between TPPS and CD on the protein surface. The BSA-CD/TPPS complex further complexed with ferric protoporphyrin IX (hemin) in the hydrophobic pockets of albumin to form a hemin/BSA-CD/TPPS ternary complex in which static fluorescence quenching occurred owing to intramolecular electron transfer from the photoexcited TPPS to hemin.