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We consider a nematic slab with homeotropic anchoring and investigate the effect of a magnetic field, H, parallel to the plates and an electric field, E, perpendicular to them $(\epsilon_{\rm a} < 0,~\chi_{\rm a} > 0)$. The magnetic field is either fixed, or rotating at a frequency ω around an axis perpendicular to the plate. The main effect consists in an Ising-Bloch transition of the walls observed either in the ($H^2,~E^2$) or ($H^2,~\omega$) parameter space. The latter case corresponds to the experimental observation recently made at Brandeis University [1]. Some of these results are understood within the framework of a Ginzburg-Landau model, directly derived from the Oseen-Zocher-Frank expression for nematic elasticity, which accounts for the main static and dynamic experimental phenomena observed. The spiral shaped textures obtained in the dynamic case probably represent one of the first simple physical analogs of the chemical and biological phenomena observed in excitable media.

Abstract: Grateloupia turuturu Yamada is the currently accepted name for the invasive red alga that is present on coasts of the North Atlantic. Previously considered as G. doryphora (Montagne) M.A. Howe, populations of this invasive species were examined and their taxonomic position revised using molecular and morphological techniques. It was also thought that similar invasive populations in the Mediterranean should be identified as G. turuturu. This investigation used rbcL based molecular analyses to clarify the taxonomic position of Grateloupia “doryphora’ from the Straits of Messina. Our results indicate that this population is neither G. doryphora nor G. turuturu. It was placed separately in all analyses and grouped consistently with other Grateloupia species from the Pacific. On the basis of molecular data from this and previous investigations, it is evident that the status of the foliose Atlantic and Mediterranean entities is still unclear and a re-evaluation of the old names connected to them should be undertaken.

Abstract: Mediterranean reports of Gracilariaceae species, in particular those assigned to the G. verrucosa complex, were re-examined with the use of molecular tools, in order to verify their systematic position and better understand their distribution. Within this complex, we recognized four distinct taxa: Gracilariopsis longissima, Gracilaria gracilis, Gracilaria longa and a possible new species. The rbcL gene sequences, together with those of other terete Mediterranean entities, were included in a broad molecular phylogeny of the family. The reproductive characters of the studied taxa do not fit completely with published hypothesis on the generic and intrageneric relationships, suggesting that the anatomy of some subgroups should be better characterized.

AbstractThe life history of Bangia atropurpurea(Bangiales, Rhodophyta) from the Alcantara River (Sicily, Italy) was studied in the field and laboratory. An alternation between a macroscopic phase and a microscopic filamentous conchocelis phase was found, and spermatia and carpogonia are described for the first time in a freshwater population of the species. Endosporangia have also been discovered on gametophytic plants in culture. In addition, the conchocelis phase produced either conchosporangia or monosporangia, and reproduction by fragmentation was common. Sexuality was indicated by chromosome counts of n= 3 and 2n=6 in gametophytes and sporophytes, respectively; resting cells were observed in both.

The gene for rhodopsin, the primary light sensor of the visual system, is specifically expressed in the rod photoreceptor cells of the retina. We show here that in the rat, opsin RNA first accumulates to detectable levels at postnatal day 2 (PN2) and that nascent transcripts can be detected at PN1; this is the time when peak numbers of photoreceptor cells are generated by the final division of their neuroepithelial precursors. Accumulated opsin RNA then increases to reach the adult level, 0.06% of total retinal RNA, at about PN10. The transcription rate of the opsin gene increases to a similar extent over the same time course between PN3 and adulthood, suggesting that transcriptional activation is responsible for the increase in opsin expression. We used the antibody RET-P1 to show that rhodopsin protein is also detectable at PN2 and that the number of cells expressing the protein increases with time in a central-to-peripheral gradient in the retina. This increase in the number of differentiating photoreceptors in the tissue appears to account for much of the increase in opsin gene transcription and RNA accumulation. In situ hybridization to opsin RNA shows that it is restricted to the photoreceptor layer from the time it can first be detected, at PN7. Later in development, when RET-P1 staining shifts to the photoreceptor outer segments, opsin RNA becomes localized to the inner segments, suggesting that the distributions of opsin protein and RNA are related.

GH and somatomedin-C response to acute hpGRF-44 iv administration (1 μg/ Kg bw) was studied in 16 patients with hypopituitarism (GHD) and in 7 constitutionally short subjects. GH-deficient patients evidenced a significant GH increase peaking between 15 and 60 min. (4.95 ± 0.88 ng/ml, mean ± SE) (p< 0.01 vs placebo). In non GH-deficient subjects GH increase was more pronounced (peak 18.00 ± 3.01 ng/ml; p< 0.01 vs both placebo and GHD group). Acid-extractable somatomedin-C was slightly, but significantly higher than baseline at 12th h (p< 0.01) in both patients with hypopituitarism (basal value: 0.067 ± 0.021 U/ml; 12 h: 0.096 ±0.024 U/ml) and constitutionally short subjects (basal value 0.62 ± 0.13; 12h 0.72 ± 0.16 U/ml). In 3 subjects with hypopituitarism multiple iv administrations (1 μg/kg bw at 09:30 and 21:30 h for 4 days) produced on the average a modest increase of the GH responsiveness, were more effective to enhance somatomedin-C concentration, but not sufficient to reach normal levels. Sc administration of the same dose at 4-h intervals by a programmable portable pump — performed on 6 GHD subjects — produced an increase of GH peak response on the 4th day of treatment (1.38 ± 0.31 ng/ml) with respect to the one observed on the first day (0.42 ± 0.09 ng/ml). Somatomedin-C increase was low and inconstant. These data support the use of a 4–5-day pulsatile treatment in the differentiation between hypothalamic and pituitary deficiency, and the possibility of therapeutical use of GRF with the same protocol when a response is evidenced.

We consider a nematic slab with homeotropic anchoring and investigate the effect of a magnetic field, H, parallel to the plates and an electric field, E, perpendicular to them (?a< 0,??a> 0). The magnetic field is either fixed, or rotating at a frequency ? around an axis perpendicular to the plate. The main effect consists in an Ising-Bloch transition of the walls observed either in the (H2,?E2) or (H2,??) parameter space. The latter case corresponds to the experimental observation recently made at Brandeis University [1]. Some of these results are understood within the framework of a Ginzburg-Landau model, directly derived from the Oseen-Zocher-Frank expression for nematic elasticity, which accounts for the main static and dynamic experimental phenomena observed. The spiral shaped textures obtained in the dynamic case probably represent one of the first simple physical analogs of the chemical and biological phenomena observed in excitable media. Nous avons ?tudi?, sur une lamelle n?matique, avec un ancrage hom?otrope, l'effet d'un champ magn?tique, H, parall?le aux lames, associ? ? un champ ?lectrique, E, parall?le ? ces derni?res (?a< 0,??a> 0). Le champ magn?tique peut ?tre fixe ou tournant ? une vitesse ? autour d'un axe perpendiculaire aux lames. Le principal effet ?tudi? ici concerne une transition Ising-Bloch des parois, observ?e dans les espaces de param?tres (H2,?E2) ou (H2,??). Ce dernier cas correspond ? l'observation exp?rimentale r?cemment r?alis?e ? l'Universit? de Brandeis [1]. Certains de ces r?sultats sont interpr?t?s ? l'aide d'un mod?le ? la Ginzburg-Landau directement d?duit de l'expression de Oseen-Zocher-Frank de l'?lasticit? des n?matiques. Les textures constitu?es de spirales obtenues dans le cas dynamique sont probablement l'un des premiers analogues physiques simples des spirales chimiques et biologiques ?tudi?es dans le domaine des milieux excitables.

Plasma and tissue of certain vertebrates contain a protein called saxiphilin that specifically binds the neurotoxin saxitoxin with nanomolar affinity. We describe the isolation of a cDNA clone of saxiphilin from liver of the North American bullfrog (Rana catesbeiana). The cDNA sequence encodes a protein that is evolutionarily related to members of the transferrin family of Fe(3+)-binding proteins. Pairwise sequence alignment of saxiphilin with various transferrins reveals amino acid identity as high as 51% and predicts 14 disulfide bonds that are highly conserved. The larger size of saxiphilin (91 kDa) versus serum transferrin (approximately 78 kDa) is primarily due to a unique insertion of 144 residues. This insertion contains a 49-residue domain classified as a type 1 repetitive element of thyroglobulin, which is shared by a variety of membrane, secreted, and extracellular matrix proteins. Saxiphilin also differs from transferrins in 9 of 10 highly conserved amino acids in the two homologous Fe3+/HCO3-binding sites of transferrin. Identification of saxiphilin implies that transferrin-like proteins comprise a diverse superfamily with functions other than iron binding.

A recombinant plasmid containing sequences complementary to human pro-alpha l(I) collagen mRNA was used for the chromosomal assignment of the pro-alpha l(I) collagen gene. Restriction endonuclease analysis of DNA from mouse-human and Chinese hamster-human somatic cell hybrids revealed cosegregation with human chromosome 17. Hybrids containing derivative chromosomes with a t(2;17)(q14;q21) translocation showed cosegregation of the pro-alpha l(I) gene with the segment 17q21 leads to qter. In situ hybridization on human metaphasic chromosomes confirmed this conclusion.