A Golgi study of the hypothalamus of Actinopterygii

The posterior hypothalami of the polypteriform, Calamoichthys, and of the teleost, Anguilla, were studied by means of the Golgi technique. In Calamoichthys, the lateral lobes are not developed and the median lobe is simple. In Anguilla, the median (tuberal) lobe shows lophodendritic, CSF-contacting cells and horizontal cells in the periventricular grey and some reticular elements directed toward the cell-poor lateral areas. In the lateral lobes the periventricular grey is formed by multipolar neurons and a diffuse population of multipolar cells of uncertain identity. The nucleus diffusus lobi lateralis is formed by scarce multipolar neurons, often placed next to the external surface of the brain. The organization of the lateral lobes in Actinopterygii is reminiscent of highly developed integrative regions.     

Molecular requirements for attachment of the glycosylphosphatidylinositol anchor to the human alpha folate receptor

The alpha isoform of the folate receptor (FR) is a 38-KDa glycosylphosphatidylinositol (GPI) protein which mediates the internalization of folates. The FR amino acid sequence has features typical of GPI-linked proteins, including the presence of a hydrophobic carboxyl-terminus, a hinge region, and a stretch of small and uncharged amino acids. Substitution of predicted cleavage/attachment Ser234 with arginine or threonine, or replacement of Gly235 with proline by site-directed mutagenesis had no effect on GPI processing. In fact, CHO cells transfected with each of the three cDNA variants or with FR wild-type showed comparable amounts of phosphatidylinositol-specific phospholipase C-resistant FR in double-determinant radioimmunoassay. Western blot analysis of total cell lysates from all transfectants consistently revealed the 38-KDa FR band. Deletion of residues 233-237 in the amino-terminal portion of the FR cDNA constructs derived by a polymerase chain reaction strategy abrogated GPI processing, with only a small proportion of the FR remaining in the cytoplasm in four of the five clones tested. This finding suggests that FR residues 233-237 are essential in properly juxtaposing the FR hydrophobic domain. Together, these data support the hypothesis that the postulated Ser234 is not the only potential cleavage/attachment site of the alpha isoform of FR.     

Parasites make male pipefish careless

Parasite-mediated sexual selection is expected to favour the avoidance of matings with infected individuals. However, the extent to which the costs and benefits of discriminating against parasitized mates trade off may depend upon numerous factors. I investigated the effects of sex and infection status on choosiness in sex-role reversed deep-snouted pipefish (Syngnathus typhle L.) that were either artificially infected with the trematode parasite Cryptocotyle sp. or sham-infected. Sham-infected males were significantly more likely to associate with a sham-infected female rather than with a Cryptocotyle-infected female. Infected males failed to discriminate against infected potential partners. Males were choosier the larger they were relative to the females available for choice. Females were not discriminatory, regardless of their infection status. Given an inverse relation between female fecundity and parasite load, choosy unparasitized males may gain enhanced reproductive success from their choice decisions. In contrast, more heavily infected wild-caught males gave birth to slightly fewer, but not smaller offspring than did uninfected or lightly infected males, suggesting only a low direct premium on choosy females. The detrimental effects of parasitism on male choosiness, and the lack of female discrimination against infected males likely have profound repercussions on the strength of sexual selection acting on the two sexes and on the dynamics of host-parasite interactions in this system.     

Highly efficient technetium-99m labeling procedure based on the conjugation of N-[N-(3-diphenylphosphinopropionyl)glycyl]cysteine ligand with poly(ethylene glycol)

The PN(2)S N-(N-(3-diphenylphosphinopropionyl)glycyl)cysteine ligand was conjugated to methoxy-poly(ethylene glycol)-amino (mPEG-NH(2)) 5 and 20 kDa to yield PN(2)S(Trt)-PEG(5000) 1 and PN(2)S(Trt)-PEG(20000) 2, and then detritylated to PN(2)S-PEG(5000) 4 and PN(2)S-PEG(20000) 5. When an acidic solution of (99m)TcO(4)(-) is added to 4 or 5 in solid form, a quantitative yield in a single labeled species, (99m)Tc-labeled PN(2)S-PEG(5000) 9 and (99m)Tc-labeled PN(2)S-PEG(20000) 10, respectively, is obtained. The reaction occurs in less than 15 min at room temperature for 4 and 35 degrees C for 5. This labeling procedure avoids the use of an external reducing agent, and it is based on the amphiphilic properties of PN(2)S-PEGs. Once in water, 4 and 5 self-assemble in micelles, which catalyze the metal reduction by means of an electron pair transfer from the phosphorus to technetium. The [(99m)TcO](3+) species is then coordinated, and at micelle level, both the (P)ON(2)S and the PN(2)S coordinations are possible, as demonstrated by reacting (99m)Tc-gluconate and ReOCl(3)(PPh(3))(2) with 4 and 5 and with the oxidized analogous (P)ON(2)S-PEG(5000) 6. Compounds 9 and 10 exhibited a high stability both in vitro and in vivo. Biodistribution studies in mice also indicated that PN(2)S linking and (99m)Tc labeling do not modify PEG behavior in water and in vivo since the polymer dictates the fate of the conjugate.     

No evidence for increased extinction proneness with decreasing effective population size in a parasitoid with complementary sex determination and fertile diploid males

Background  

In species with single locus complementary sex determination (sl-CSD), the sex of individuals depends on their genotype at one single locus with multiple alleles. Haploid individuals are always males. Diploid individuals are females when heterozygous, but males when homozygous at the sex-determining locus. Diploid males are typically unviable or effectively sterile, hence imposing a genetic load on populations. Diploid males are produced from matings of partners that share an allele at the sex-determining locus. The lower the allelic diversity at the sex-determining locus, the more diploid males are produced, ultimately impairing the growth of populations and jeopardizing their persistence. The gregarious endoparasitoid wasp Cotesia glomerata is one of only two known species with sl-CSD and fertile diploid males.     

Baroreflex dysfunction in rats submitted to protein restriction

Earlier studies from the authors' laboratory showed that malnourishment induces alterations in the cardiovascular homeostasis increasing the basal mean arterial pressure and heart rate. In this study, the authors evaluated whether the sympathetic and parasympathetic efferent activities contribute to changes in the cardiovascular homeostasis through altered modulation of the arterial baroreflex of malnourished rats. After weaning, male Fischer rats were given 15% (Normal Protein--NP) or 6% (Low Protein--LP) protein diet for 35 d. The baroreflex gain and latency were evaluated before and after selective autonomic blockades in control and malnourished rats. It was observed that malnourishment affected the baroreflex gain in response to activation and deactivation of the arterial baroreflex. Moreover, malnourished rats showed increased baroreflex latency as compared to that of control rats. Regarding the autonomic efferent activity directed to the heart, the data showed increased sympathetic and decreased parasympathetic efferent activities in malnourished rats, and such alterations could be related to the observed changes in the arterial baroreflex gain as well as in the basal mean arterial pressure and heart rate.     

Frequency-dependent baroreflex modulation of blood pressure and heart rate variability in conscious mice

The goal of this study was to determine the baroreflex influence on systolic arterial pressure (SAP) and pulse interval (PI) variability in conscious mice. SAP and PI were measured in C57Bl/6J mice subjected to sinoaortic deafferentation (SAD, n = 21) or sham surgery (n = 20). Average SAP and PI did not differ in SAD or control mice. In contrast, SAP variance was enhanced (21 +/- 4 vs. 9.5 +/- 1 mmHg2) and PI variance reduced (8.8 +/- 2 vs. 26 +/- 6 ms2) in SAD vs. control mice. High-frequency (HF: 1-5 Hz) SAP variability quantified by spectral analysis was greater in SAD (8.5 +/- 2.0 mmHg2) compared with control (2.5 +/- 0.2 mmHg2) mice, whereas low-frequency (LF: 0.1-1 Hz) SAP variability did not differ between the groups. Conversely, LF PI variability was markedly reduced in SAD mice (0.5 +/- 0.1 vs. 10.8 +/- 3.4 ms2). LF oscillations in SAP and PI were coherent in control mice (coherence = 0.68 +/- 0.05), with changes in SAP leading changes in PI (phase = -1.41 +/- 0.06 radians), but were not coherent in SAD mice (coherence = 0.08 +/- 0.03). Blockade of parasympathetic drive with atropine decreased average PI, PI variance, and LF and HF PI variability in control (n = 10) but had no effect in SAD (n = 6) mice. In control mice, blockade of sympathetic cardiac receptors with propranolol increased average PI and decreased PI variance and LF PI variability (n = 6). In SAD mice, propranolol increased average PI (n = 6). In conclusion, baroreflex modulation of PI contributes to LF, but not HF PI variability, and is mediated by both sympathetic and parasympathetic drives in conscious mice.     

Genotype of inflammatory cytokines in limbal stem cell graft in Italian patients

We tested the hypothesis that the genetic capability to mount an inflammatory response might contribute to the inter-individual variability of limbal stem cell graft (LSCG) outcome. Two functional polymorphisms in the IL-6 and TNF-alpha promoter regions were genotyped in 35 patients. A new score system (clinical assessment score, CAS) was set up in order to classify patients' clinical profile, and the main parameters relevant for LSCG as well as for the follow-up of the patients. Patients carrying at both loci a genotype associated with a lower production of both cytokines were classified as "low producers" (LP), while all the others were classified as "intermediate or high producers" (HP). LP patients did not show any difference in CAS before and after transplantation while a significant difference was present in HP patients. A similar trend was evident in the 35 months of follow-up. Polymorphisms of IL-6 and TNF-alpha can be used to identify subgroups of patients with higher risk of unsuccessful outcome.     

The stable carbon and nitrogen isotopic composition of vegetation in tropical forests of the Amazon Basin, Brazil

Here we present the within-site, seasonal, and interannual variations of the carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope ratios of leaves, wood, bark and litter from four sites in the Amazon region, Brazil. Samples were collected in Manaus (3° 06′07′′ S; 60°01′30′′ W), Ji-Paraná (10°53′07′′ S; 61°57′06′′ W), and Santarém (2°26′35′′ S; 54°42′30′′ W) with mean annual precipitation of 2207, 2040 and 1909 mm respectively. The overall average for all leaf samples was for δ¹³C and for δ¹⁵N (n=756). The leaf δ values at these sites were often but not always statistically distinct from each other. The δ¹³C values varied from to . Pronounced differences in δ¹³C values occurred with height associated with differences in forest structure. The δ¹³C of leaf dry matter showed seasonal variations associated with the length of the dry season, despite the fact that total annual precipitation was similar among the studied sites. Leaf δ¹⁵N values ranged from to a maximum value of , and the Santarém sites showed more enriched values than Manaus and Ji-Paraná sites. No seasonal variation was detected in the δ¹⁵N of leaves, but significant differences were observed among sites and with changes in canopy height. The isotope ratio data are consistent with our current understanding of the roles of light, water availability, and recycling of soil-respired CO₂ influences on δ¹³C and consistent with our understanding that an open nitrogen cycle can lead to high δ¹⁵N values despite a significant number of legumes in the vegetation.