Hematologic and hematochemical characteristics of the herring gull (Larus argentatus) and the buzzard (Buteo buteo)

Some hematological and hematochemical parameters in eight herring gulls (Larus argentatus) and in six buzzards (Buteo buteo) were checked. The buzzards were fed with ovine meat exclusively, while the herring gulls were fed with fish and ovine meat. Considerable differences between the two species were noted, particularly as far as the hematological and lipidic parameters are concerned. These differences are probably related to the aquatic life of the herring gull.     

Feedback effects of ovarian steroids on the hypothalamic-hypophyseal axis in the rabbit

The feedback effects of two ovarian steroids, estradiol-17 beta (E2) and 20 alpha-hydroxypregn-4-en-3-one (20 alpha OH), were examined in both intact (INT) and ovariectomized (OVEX) does. We measured steroid-induced alterations in endogenous gonadotropin-releasing hormone (GnRH) from sequential 10-min samples of hypothalamic perfusates, simultaneous changes in peripheral plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and the modification of pituitary responsiveness, i.e., increments in plasma LH (delta LH) and plasma FSH (delta FSH), after 50 ng, 250 ng, and 1 microgram of exogenous GnRH in individual does of 6 treatment groups. The groups were: INT does, OVEX does, OVEX does receiving either one (1 E2) or two (2 E2) E2-filled Silastic capsules, OVEX does receiving a 20 alpha OH-filled capsule (20 alpha OH), and OVEX does receiving both capsules of E2 and 20 alpha OH (1 E2 + 20 alpha OH). Ovariectomy enhanced the pulsatile release of hypothalamic GnRH and pituitary LH and FSH, and increased the LH response (delta LH) to exogenous GnRH (OVEX vs. INT, p less than 0.05). Replacement of E2 at the time of ovariectomy prevented the increased GnRH and gonadotropin secretion as well as the enhanced delta LH that were observed in untreated OVEX does. The release of hypothalamic GnRH in the 20 alpha OH group was lower (p less than 0.05) than that in the OVEX group and not different from that in the INT group. The release of pituitary LH and FSH and the delta LH in the 20 alpha OH group was not different from that in the OVEX group, but these parameters were greater (p less than 0.05) than those in the INT group. The hypothalamic GnRH pulse frequency in the 1 E2 + 20 alpha OH group was lower (p less than 0.05) than that in either the 1 E2 or the 20 alpha OH group, but the delta LH in the 1 E2 + 20 alpha OH group was not different from that in either the 1 E2 or the 20 alpha OH group. The highest dose (1 microgram) of exogenous GnRH stimulated a modest increase in FSH in the OVEX, 20 alpha OH, 1 E2 + 20 alpha OH, and 1 E2 groups; but a steroid effect on delta FSH among these 4 groups was not apparent.(ABSTRACT TRUNCATED AT 250 WORDS)     

Significance of the recognition of certain antigenic regions on the human thyroglobulin molecule by natural autoantibodies from healthy subjects

We have evaluated the epitope specificity of natural antihuman thyroglobulin (hTg) autoantibodies (aAb) in the plasma of healthy individuals. By an indirect ELISA technique, we selected 56 plasma samples with high anti-hTg antibody activity and used the IgG fraction isolated from these plasma to study the antigenic domains on the hTg molecule recognized by the natural anti-hTg aAb. A panel of 15 mAb, coupled to alkaline phosphatase and recognizing six regions (I to VI) on the hTg molecule, served to identify the domains recognized by the natural anti-hTg aAb using a competitive ELISA procedure. A total of 26 of the IgG fractions was found to interact with at least one of the regions defined by our battery of mAb. Region V was recognized by the majority of the IgG fractions. Interestingly, region II was rarely recognized by the same IgG fraction that reacted with region V. Inasmuch as we have previously shown that region II is mainly recognized by aAb in the serum of subjects with various thyroid disorders, we propose that recognition of region V reflects the normal physiologic state of the immune system with respect to the hTg molecule.     

Auxin Influx Carriers Control Vascular Patterning and Xylem Differentiation in Arabidopsis thaliana

Auxin is an essential hormone for plant growth and development. Auxin influx carriers AUX1/LAX transport auxin into the cell, while auxin efflux carriers PIN pump it out of the cell. It is well established that efflux carriers play an important role in the shoot vascular patterning, yet the contribution of influx carriers to the shoot vasculature remains unknown. Here, we combined theoretical and experimental approaches to decipher the role of auxin influx carriers in the patterning and differentiation of vascular tissues in the Arabidopsis inflorescence stem. Our theoretical analysis predicts that influx carriers facilitate periodic patterning and modulate the periodicity of auxin maxima. In agreement, we observed fewer and more spaced vascular bundles in quadruple mutants plants of the auxin influx carriers aux1lax1lax2lax3. Furthermore, we show AUX1/LAX carriers promote xylem differentiation in both the shoot and the root tissues. Influx carriers increase cytoplasmic auxin signaling, and thereby differentiation. In addition to this cytoplasmic role of auxin, our computational simulations propose a role for extracellular auxin as an inhibitor of xylem differentiation. Altogether, our study shows that auxin influx carriers AUX1/LAX regulate vascular patterning and differentiation in plants.     

Structural Characterization of the Natively Unfolded N-Terminal Domain of Human c-Src Kinase: Insights into the Role of Phosphorylation of the Unique Domain

The N-terminal regions of the members of Src family of non-receptor protein tyrosine kinases are intrinsically unfolded and contain the maximum sequence divergence among them. In this study, we have addressed the structural characterization by nuclear magnetic resonance of this region of 84 residues that encompasses the SH4 and the unique domains (USrc) of the human c-Src. With this aim, the backbone assignment was performed using ¹³C-detected experiments that overcome the spectral resolution problems and the large number of prolines that are typical for intrinsically unfolded proteins. The analysis of the residual dipolar couplings measured for the USrc indicates the presence of a low populated helical structure in the 60-75 region. No long-range contacts between remote fragments of the chain were detected with paramagnetic relaxation enhancement experiments. The structural characterization was extended to two different phosphorylation states of USrc that encompassed three different phosphorylated sites, Ser17, Thr37, and Ser75. The structural and conformational changes upon phosphorylation were monitored through chemical shift perturbations and residual dipolar couplings, indicating that modifications occur at local level and no global rearrangements were apparent. These results suggest a scenario where phosphorylation induces a global electrostatic perturbation that could be involved in the membrane unbinding of c-Src and that could be related with the localization of the enzyme. These observations suggest the unique domain of Src kinases as a source of selectivity and reinforce the relevant role of intrinsically disordered proteins in biological processes.     

Influence of interactions on water and aroma permeabilities of ι-carrageenan–oleic acid–beeswax films used for flavour encapsulation

The objective of this work is to investigate the water and aroma barrier properties of films obtained from ι-carrageenan containing glycerol and lipids mixtures of oleic acid (OA) and beeswax (BW) used for encapsulation of active compounds. Water vapor permeability (WVP) is greatly influenced by lipid composition, encapsulated aroma compound and also relative humidity. WVP decreases when films contain encapsulated aroma compound but increases when the moisture content in the films increases. When oleic acid was the main compound of lipid phase, the plasticizing effect of water revealed through water permeability is less marked. The results of ethyl acetate, ethyl butyrate, ethyl hexanoate, 2-hexanone, 1-hexanol and cis-3-hexenol permeabilities reveal that physicochemical interactions between aroma compounds-hydrocolloid and aroma compound-lipid induce structural changes and modify their permeability. This work gives evidence of the ability of ι-carrageenan–OA–BW films to protect encapsulated aroma compound and its influence in barrier properties.