Optical Confinements in Correlated Spectral Characteristics of Vertically Aligned Silicon Nanometric Wires Followed by a Facile Fabrication Thereof

Nanometric wires, in particular, vertically aligned silicon nanowires, possess a huge prospect in current thin film solar cell technologies. A bottom-up process to acquire vertically aligned silicon nanowire (Si-NW) on c-Si wafer was demonstrated and characterized. A well coverage of Si-NWs on c-Si, ca. 6.5 × 10⁸/cm², was obtained. SEM micrograph confirmed a variation in Si-NW size in length as well as in diameter. On the other hand, inherent optical characteristics of nanometric wires define the performance of such nanowire-based thin film solar cell. Therefore, key factors, such as absorption profile, energy flow, electromagnetic (EM) field, and generation rate distribution in typical model, “Si-NW on c-Si slab,” have been observed at different wavelengths of solar spectrum. A single Si-NW of cylindrical shape was modelled on c-Si and optimized to elucidate the aforementioned characteristics. Light absorption at 700 nm was found to be the best in this scenario, and therefore, EM field and Poynting vector distribution were simulated at the same wavelength. It was revealed that at 700 nm, strongest sites of EM field and energy flow became more available and confined. Exciton generation rate was found to be distributed and confined all the way down to the bottom of the wire. A correlated phenomenon such as optical confinements in spectral characteristics in nanoscale is elucidated. Such a focused prediction in spectral optical characteristics and facile fabrication route is indispensable in optoelectronics as well as nanowire-based advanced electronic design.     

The improved incorporation of polyunsaturated fatty acids and changes in liver structure in larval gilthead seabream fed on microdiets

Two feeding experiments were conducted to evaluate the suitability of two commercial microdiets as a complementary food for the rearing of larval gilthead seabream Sparus aurata . The effect of these diets on growth, survival and total lipid composition, as well as the histological structure of the liver were examined. The results of the first trial highlighted water quality as an important factor for the survival of microdiet-fed larvae. An increase in water flow rate improved larval survival despite a reduction in live food supply. An effect of tank design on larval growth and survival was observed also and seems to be related with the light level inside the tanks; wider light grey tanks gave better results than narrower black ones. Microdiet feeding significantly improved larval growth and increased hepatocyte diameter and presence of PAS positive vacuoles suggesting an increased glycogen storage in comparison with that of larvae fed live prey only. Artificial diets provided the larvae with a higher amount of lipids and polyunsaturated fatty acids of the n-3 series, resulting in a higher DHA content in the total lipid of the larvae fed on microdiets.     

Biosynthesis of hepatitis B virus e antigen: directed mutagenesis of the putative aspartyl protease site.

The C gene products of all mammalian hepadnaviruses contain a region with sequence similarities to the catalytic center of the aspartyl proteases. This region could have the capacity to cleave precore proteins, leading to the synthesis of e antigen. By site-directed mutagenesis on a plasmid containing the hepatitis B virus C gene, we have replaced either the Asp residue of the putative aspartyl protease catalytic center or an Asp residue located 3 amino acids upstream. Transient expression of the mutated hepatitis B virus C gene in human and mouse cells showed that none of these mutations prevented the secretion of an accurately processed HBe antigen. Thus, we demonstrated that the aspartyl protease responsible for e antigen precursor processing is not C gene encoded but is more likely to be a cellular enzyme. From these results, we suggest a model for the mechanism of e antigen synthesis.     

Expression profile of nuclear receptors along male mouse nephron segments reveals a link between ERRβ and thick ascending limb function

The nuclear receptor family orchestrates many functions related to reproduction, development, metabolism, and adaptation to the circadian cycle. The majority of these receptors are expressed in the kidney, but their exact quantitative localization in this ultrastructured organ remains poorly described, making it difficult to elucidate the renal function of these receptors. In this report, using quantitative PCR on microdissected mouse renal tubules, we established a detailed quantitative expression map of nuclear receptors along the nephron. This map can serve to identify nuclear receptors with specific localization. Thus, we unexpectedly found that the estrogen-related receptor β (ERRβ) is expressed predominantly in the thick ascending limb (TAL) and, to a much lesser extent, in the distal convoluted tubules. In vivo treatment with an ERR inverse agonist (diethylstilbestrol) showed a link between this receptor family and the expression of the Na⁺,K⁺-2Cl⁻ cotransporter type 2 (NKCC2), and resulted in phenotype presenting some similarities with the Bartter syndrom (hypokalemia, urinary Na⁺ loss and volume contraction). Conversely, stimulation of ERRβ with a selective agonist (GSK4716) in a TAL cell line stimulated NKCC2 expression. All together, these results provide broad information regarding the renal expression of all members of the nuclear receptor family and have allowed us to identify a new regulator of ion transport in the TAL segments.     

Localisation of the Vacuolar Proton Pump (V-H+-ATPase) and Carbonic Anhydrase II in the Human Eccrine Sweat Gland

The localisation of the vacuolar proton pump (V-H+ -ATPase) and the enzyme carbonic anhydrase II (CAII) was investigated in the human eccrine sweat gland employing standard immunohistochemical techniques after antigen retrieval using microwave heat treatment and high pressure. The high-pressure antigen retrieval unmasked the presence of V-H+ -ATPase in the clear cells of the secretory coil, with a distribution similar to that previously observed for CAII. However, the dark cells were unreactive to both antibodies. In addition, heat and high-pressure antigen retrieval demonstrated the presence of CAII in the apical zone of luminal cells of the reabsorptive duct, a location not previously reported. The localisation of V-H+ -ATPase and CAII in the secretory coil clear cells suggests that the formation of HCO3- and H+ by carbonic anhydrase II and the transport of H+ by V-H+ -ATPase may play an role in sweat fluid secretion. Their presence at the apex of the duct cells indicates involvement in ductal ion reabsorption.     

Evolution of sex chromosomes prior to speciation in the dioecious Phoenix species

Understanding the driving forces and molecular processes underlying dioecy and sex chromosome evolution, leading from hermaphroditism to the occurrence of male and female individuals, is of considerable interest in fundamental and applied research. The genus Phoenix, belonging to the Arecaceae family, consists uniquely of dioecious species. Phylogenetic data suggest that the genus Phoenix has diverged from a hermaphroditic ancestor which is also shared with its closest relatives. We have investigated the cessation of recombination in the sex‐determination region within the genus Phoenix as a whole by extending the analysis of P. dactylifera SSR sex‐related loci to eight other species within the genus. Phylogenetic analysis of a date palm sex‐linked PdMYB1 gene in these species has revealed that sex‐linked alleles have not clustered in a species‐dependent way but rather in X and Y‐allele clusters. Our data show that sex chromosomes evolved from a common autosomal origin before the diversification of the extant dioecious species.     

Dynamic rearrangement of the filamentous actin network occurs during zoosporogenesis and encystment in the oomycete phytophthora cinnamomi

The organization of filamentous actin (F-actin) in living cells of the oomycete Phytophthora cinnamomi was determined during zoosporogenesis and zoospore encystment by microinjecting sporangia with fluorescently labeled phalloidin and observing resultant fluorescence by confocal microscopy. In multinucleate sporangia prior to the induction of cleavage, phalloidin labeling took the form of plaques which occurred mainly in the periphery of the sporangia. After induction of cleavage, phalloidin labeling showed that the plaques disappeared and that F-actin began to accumulate along the developing cleavage planes and around nuclei and water expulsion vacuoles. F-actin labeling was also observed near the plasma membrane in zoospores and young cysts but reverted to the plaque form in older cysts. Localization of F-actin close to the developing cleavage planes is consistent with the idea that actin microfilaments function in the positioning and expansion of the cleavage membranes. Observations of plaques of actin in living sporangia provide evidence that plaques are not aldehyde-induced fixation artifacts. Copyright 1998 Academic Press.     

Serglycin expression during monocytic differentiation of U937-1 cells

Serglycin is the major proteoglycan in most hematopoietic cells, including monocytes and macrophages. The monoblastic cell line U937-1 was used to study the expression of serglycin during proliferation and differentiation. In unstimulated proliferating U937-1 cells serglycin mRNA is nonconstitutively expressed. The level of serglycin mRNA was found to correlate with the synthesis of chondroitin sulfate proteoglycan (CSPG). The U937-1 cells were induced to differentiate into different types of macrophage-like cells by exposing the cells to PMA, RA, or VitD3. These inducers of differentiation affected the expression of serglycin mRNA in three different ways. The initial upregulation seen in the normally proliferating cells was not observed in PMA treated cells. In contrast, RA increased the initial upregulation, giving a reproducible six times increase in serglycin mRNA level from 4 to 24 h of incubation, compared to a four times increase in the control cells. VitD3 had no effect on the expression of serglycin mRNA. The incorporation of (35S)sulfate into CSPG decreased approximately 50% in all three differentiated cell types. Further, the (35S)CSPGs expressed were of larger size in PMA treated cells than controls, but smaller after RA treatment. This was due to the expression of CSPGs, with CS-chains of 25 and 5 kDa in PMA and RA treated cells, respectively, compared to 11 kDa in the controls. VitD3 had no significant effect on the size of CSPG produced. PMA treated cells secreted 75% of the (35S)PGs expressed, but the major portion was retained in cells treated with VitD3 or RA. The differences seen in serglycin mRNA levels, the macromolecular properties of serglycin and in the PG secretion patterns, suggest that serglycin may have different functions in different types of macrophages.      

<Emphasis Type="Italic">α</Emphasis>-Amylase inhibitor-1 gene from <Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> expressed in <Emphasis Type="Italic">Coffea arabica</Emphasis>plants inhibits α-amylases from the coffee berry borer pest

Background  

Coffee is an important crop and is crucial to the economy of many developing countries, generating around US70 billion per year. There are 115 species in the < i > Coffea < /i > genus, but only two, < i > C. arabica < /i > and < i > C. canephora < /i > , are commercially cultivated. Coffee plants are attacked by many pathogens and insect-pests, which affect not only the production of coffee but also its grain quality, reducing the commercial value of the product. The main insect-pest, the coffee berry borer ( < i > Hypotheneumus hampei < /i > ), is responsible for worldwide annual losses of around US70 billion per year. There are 115 species in the Coffea genus, but only two, C. arabica and C. canephora, are commercially cultivated. Coffee plants are attacked by many pathogens and insect-pests, which affect not only the production of coffee but also its grain quality, reducing the commercial value of the product. The main insect-pest, the coffee berry borer (Hypotheneumus hampei), is responsible for worldwide annual losses of around US500 million. The coffee berry borer exclusively damages the coffee berries, and it is mainly controlled by organochlorine insecticides that are both toxic and carcinogenic. Unfortunately, natural resistance in the genus Coffea to H. hampei has not been documented. To overcome these problems, biotechnological strategies can be used to introduce an α-amylase inhibitor gene (α-AI1), which confers resistance against the coffee berry borer insect-pest, into C. arabica plants.