Discriminatory Role of Detergent-Resistant Membranes in the Dimerization and Endocytosis of Prostate-Specific Membrane Antigen

Prostate-specific membrane antigen (PSMA) is a type-II membrane glycoprotein that was initially identified in LNCaP cells. It is expressed at elevated levels in prostate cancer. In view of the correlation between the expression levels of PSMA and disease grade and stage, PSMA is considered to be one of the most promising biomarkers in the diagnosis and treatment of prostate cancer. In LNCaP cells PSMA undergoes internalization via clathrin-coated pits followed by accumulation in the endosomes. PSMA associates with different types of detergent-resistant membranes (DRMs) along the secretory pathway. Its mature form is mainly insoluble in Lubrol WX, but does not associate with Triton X-100-DRMs. To understand the mechanism of PSMA internalization we investigated its association during internalization with DRMs. For this purpose, internalization was induced by antibody cross-linking. We demonstrate at the biochemical and cell biological levels that: [i] exclusively homodimers of PSMA are associated with Lubrol WX-DRMs, [ii] antibody-induced cross-linking of PSMA molecules results in a time-dependent partitioning into another DRMs type, namely Triton X-100-DRMs, and [iii] concomitant with its association with Triton-X-100-DRMs internalization of PSMA occurs along tubulin filaments. In a previous work (Colombatti et al. (2009) PLoS One 4: e4608) we demonstrated that the small GTPases RAS and RAC1 and the MAPKs p38 and ERK1/2 are activated during antibody cross-linking. As downstream effects of this activation we observed a strong induction of NF-kB associated with an increased expression of IL-6 and CCL5 genes and that IL-6 and CCL5 enhanced the proliferative potential of LNCaP cells synergistically. These observations together with findings reported here hypothesize a fundamental role of DRMs during activation of PSMA as platforms for trafficking, endocytosis and signalling. Understanding these mechanisms constitutes an essential prerequisite for utilization of PSMA as a therapeutically suitable target in prostate cancer.     

Cytogenetic study of F1 hybrids betweenCrepis dinarica andCrepis froelichiana (Asteraceae)

Crepis dinarica andC. froelichiana are two closely related species of theC. praemorsa complex. Even though they exhibit the same chromosome number (2n = 8) and similar idiogram shape, they differ widely in quantity and distribution of heterochromatin bands. The hybrids between these two species comprise three morphological types. Parental genomes were distinguished in hybrids by Giemsa differential staining (C-banding). Although meiosis presents only a few abnormalities (about 2.4%), the percentage of aborted pollen grains is very high (90%).     

Portal vein network around the liver lobules demonstrates the lobular structure of the liver

The regularity of a basketlike surrounding of parenchymatous parts of the liver by portal branches proves the lobular organization of the liver. The wall formation of the portal basket (corbicula portalis) is demonstrated by several figures.     

A new species of Polystoma (Monogenea: Polystomatidae) parasitic in Hyperolius marmoratus (Anura: Hyperoliidae) in South Africa

Polystoma marmorati n. sp. is described as a new polystomatid species parasitic in the urinary bladder of the painted reed frog Hyperolius marmoratus marmoratus collected in southern Natal, South Africa. Parasite prevalence varied from 14.5 to 47.4% and the mean intensity from 1.0 to 1.1. The hamuli of the new species have a characteristic, partly fragmented appearance, a feature also seen in Polystoma batchvarivi, the only other polystome described from a species of the genus Hyperolius. The similarity between the two species, in spite of their geographical separation, is commented upon.     

Founder effect in a Belgian-Dutch fragile X population

For many years, the high prevalence of the fragile X syndrome was thought to be caused by a high mutation frequency. The recent isolation of the FMR1 gene and identification of the most prevalent mutation enable a more precise study of the fragile X mutation. As the vast majority of fragile X patients show amplification of an unstable trinucleotide repeat, DNA studies can now trace back the origin of the fragile X mutation. To date, de novo mutations leading to amplification of the CGG repeat have not yet been detected. Recently, linkage disequilibrium was found in the Australian and US populations between the fragile X mutation and adjacent polymorphic markers, suggesting a founder effect of the fragile X mutation. We present here a molecular study of Belgian and Dutch fragile X families. No de novo mutations could be found in 54 of these families. Moreover, we found significant (P < 0.0001) linkage disequilibrium in 68 unrelated fragile X patients between the fragile X mutation and an adjacent polymorphic microsatellite at DXS548. This suggests that a founder effect of the fragile X mutation also exists in the Belgian and Dutch populations. Both the absence of new mutations and the presence of linkage disequilibrium suggest that a few ancestral mutations are responsible for most of the patients with fragile X syndrome.     

Gene-rich plastid genomes of two parasitic red algal species,Laurencia australis and L. verruciformis (Rhodomelaceae,Ceramiales), and a taxonomic revision of Janczewskia

Parasitic red algae are an interesting system for investigating the genetic changes that occur in parasites. These parasites have evolved independently multiple times within the red algae. The functional loss of plastid genomes can be investigated in these multiple independent examples, and fine-scale patterns may be discerned. The only plastid genomes from red algal parasites known so far are highly reduced and missing almost all photosynthetic genes. Our study assembled and annotated plastid genomes from the parasites Janczewskia tasmanica and its two Laurencia host species (Laurencia elata and one unidentified Laurencia sp. A25) from Australia and Janczewskia verruciformis, its host species (Laurencia catarinensis), and the closest known free-living relative (Laurencia obtusa) from the Canary Islands (Spain). For the first time we show parasitic red algal plastid genomes that are similar in size and gene content to free-living host species without any gene loss or genome reduction. The only exception was two pseudogenes (moeB and ycf46) found in the plastid genome of both isolates of J. tasmanica, indicating potential for future loss of these genes. Further comparative analyses with the three highly reduced plastid genomes showed possible gene loss patterns, in which photosynthetic gene categories were lost followed by other gene categories. Phylogenetic analyses did not confirm monophyly of Janczewskia, and the genus was subsumed into Laurencia. Further investigations will determine if any convergent small-scale patterns of gene loss exist in parasitic red algae and how these are applicable to other parasitic systems.     

Effects of the rat renotropic system on 14C-uridine incorporation into RNA and RNA precursors.

We used the incorporation of ¹⁴C-uridine into RNA of incubating kidney fragments from normal control rats to evaluate RNA metabolism. Sera from unilaterally nephrectomized rats (uni) obtained 20 hrs post-operatively stimulate ¹⁴C-uridine incorporation into RNA significantly more than sera from sham-operated rats (sham). Differently, sera from uni and sham rats have little influence on specific activities of endogenous uridine nucleotide pool in renal fragments. Renal extracts were obtained by homogenizing kidneys in saline. Extracts from kidneys of uni and sham rats 20 hrs post operation depress incorporation markedly, and each depresses to a similar extent, but kidney extracts dilute the specific activities of uridine pools. Correcting for the latter dilution demonstrates that kidney extracts alone have little effect on ¹⁴C-uridine incorporation into RNA. We then followed the results when these sera and extracts were combined. Compared to fragments incubating in sham sera and sham extracts, substitution of uni extracts or both uni extracts and uni sera enhances ¹⁴C-uridine into renal RNA, whether or not results are corrected for changes in the specific activities of the uridine pools. We conclude that after uninephrectomy there is a concurrent elevation in circulating renotropin and a tissue activating factor in the remaining kidney. The tissue factor can only form an excitor to ¹⁴C-uridine incorporation into RNA when serum is present. The rat renotropic system that enhances incorporation of ³H-thymidine into DNA also can stimulate ¹⁴C-uridine incorporation into renal RNA.     

High-performance liquid chromatographic analysis of neutral glycosphingolipids as their per-O-benzoyl derivatives

Previous reports from this laboratory (1–4) described the perbenzoylation of neutral glycosphingolipids (GSL)¹ with benzoyl chloride in pyridine and analysis of the perbenzoylated derivatives by high performance liquid chromatography (hplc). A disadvantage of this procedure is that N-benzoylation occurs as well as the desired O-benzoylation. This does not permit recovery of the parent GSL after mild alkaline hydrolysis due to formation of a mixture of N-acylated and N-benzoylated GSLs(1). It has also been demonstrated that the benzoylation with benzoic anhydride in pyridine does not lead to the formation of N-benzoylated products. However, the anhydride reaction is sluggish and the benzoyl chloride method has been the preferred procedure.Gupta et al. (5) used N,N-dimethyl-4 amino pyridine (DMAP) as a catalyst in the acylation of phospholipids by the anhydrides of fatty acids. F. B. Jungalwala (private communication) has shown that this catalyst greatly accelerates the reaction of benzoic anhydride with sulfatides.In this communication we report the preparation and hplc analysis of per-O-benzoyl derivatives of GSLs by reaction with benzoic acid anhydride in the presence of DMAP as a catalyst. Reaction with these reagents avoids amide acylation, forms single products with satisfactory chromatographic properties and parent GSLs can be regenerated by mild alkaline hydrolysis.     

Measurement of renal blood flow in the rat.

The radioactive microsphere technique is a simple method for measurement of RBF and intrarenal blood flow distribution in the rat that does not require surgical manipulation of the kidney or general anesthesia. The results are reproducible and compatible with other established techniques.     

Correction: Overcoming Stagnation in the Levels and Distribution of Child Mortality: The Case of the Philippines

Background

Health-related within-country inequalities continue to be a matter of great interest and concern to both policy makers and researchers. This study aims to assess the level and the distribution of child mortality outcomes in the Philippines across geographical and socioeconomic indicators.

Methodology

Data on 159,130 children ever borne were analysed from five waves of the Philippine Demographic and Health Survey. Direct estimation was used to construct under-five and neonatal mortality rates for the period 1980–2013. Rate differences and ratios, and where possible, slope and relative indices of inequality were calculated to measure disparities on absolute and relative scales. Stratification was undertaken by levels of rural/urban location, island groups and household wealth.

Findings

National under-five and neonatal mortality rates have shown considerable albeit differential reductions since 1980. Recently released data suggests that neonatal mortality has declined following a period of stagnation. Declines in under-five mortality have been accompanied by decreases in wealth and geography-related absolute inequalities. However, relative inequalities for the same markers have remained stable over time. For neonates, mixed evidence suggests that absolute and relative inequalities have remained stable or may have risen.

Conclusion

In addition to continued reductions in under-five mortality, new data suggests that the Philippines have achieved success in addressing the commonly observed stagnated trend in neonatal mortality. This success has been driven by economic improvement since 2006 as well as efforts to implement a nationwide universal health care campaign. Yet, such patterns, nonetheless, accorded with persistent inequalities, particularly on a relative scale. A continued focus on addressing universal coverage, the influence of decentralisation and armed conflict, and issues along the continuum of care is advocated.