Homology,limbs, and genitalia

SUMMARY Similarities in genetic control between the main body axis and its appendages have been generally explained in terms of genetic co-option. In particular, arthropod and vertebrate appendages have been explained to invoke a common ancestor already provided with patterned body outgrowths or independent recruitment in limb patterning of genes or genetic cassettes originally used for purposes other than axis patterning. An alternative explanation is that body appendages, including genitalia, are evolutionarily divergent duplicates (paramorphs) of the main body axis. However, are all metazoan limbs and genitalia homologous? The concept of body appendages as paramorphs of the main body axis eliminates the requirement for the last common ancestor of limb-bearing animals to have been provided with limbs. Moreover, the possibility for an animal to express complex organs ectopically demonstrates that positional and special homology may be ontogenetically and evolutionarily uncoupled. To assess the homology of animal genitalia, we need to take into account three different sets of mechanisms, all contributing to their positional and/or special homology and respectively involved (1) in the patterning of the main body axis, (2) in axis duplication, followed by limb patterning mechanisms diverging away from those still patterning the main body axis (axis paramorphism), and (3) in controlling the specification of sexual/genital features, which often, but not necessarily, come into play by modifying already developed and patterned body appendages. This analysis demonstrates that a combinatorial approach to homology helps disentangling phylogenetic and ontogenetic layers of homology.     

If pemphigus vulgaris IgG are the cause of acantholysis, new IgG-independent mechanisms are the concause

Pemphigus vulgaris (PV) is a disease of epidermal adhesion. Its pathogenesis is currently traced back to the action of autoantibodies against antigens located within the intercellular substance of keratinocytes, such as desmogleins and acetylcholine receptors. In the present paper, we sought to elucidate the non-IgG-mediated effects of PV sera on keratinocytes. Results showed that PV sera depleted of IgG were able to induce well-defined changes on keratinocyte morphology and metabolic activity. Indeed, PV IgG-free sera determined marked alterations on cell shape, accompanied by partial loss of keratinocyte-keratinocyte interactions within 48 h after treatment. Furthermore, PV IgG-depleted sera caused a sharp reduction of cell viability along with a less sustained weakening of intercellular adhesion strength. In light of the above findings, loss of cell-cell adhesion in PV occurs as a result of the cooperating action of both IgG and non-IgG-mediated mechanisms. These data have remarkable consequences on experimental models of PV and might open new "biological" approaches to its therapy. Thus, researchers are well advised that PV pathophysiology cannot be faithfully reproduced by leaving non-IgG serum factors out of consideration.     

Epigenetic chromatin modifiers in barley: IV. The study of barley Polycomb group (PcG) genes during seed development and in response to external ABA

Background  

Epigenetic phenomena have been associated with the regulation of active and silent chromatin states achieved by modifications of chromatin structure through DNA methylation, and histone post-translational modifications. The latter is accomplished, in part, through the action of PcG (Polycomb group) protein complexes which methylate nucleosomal histone tails at specific sites, ultimately leading to chromatin compaction and gene silencing. Different PcG complex variants operating during different developmental stages have been described in plants. In particular, the so-called FIE/MEA/FIS2 complex governs the expression of genes important in embryo and endosperm development in Arabidopsis. In our effort to understand the epigenetic mechanisms regulating seed development in barley (Hordeum vulgare), an agronomically important monocot plant cultivated for its endosperm, we set out to characterize the genes encoding barley PcG proteins.     

Relationship Between Basal Metabolic Rate,Gender, Age,and Body Composition in 8,780 White Obese Subjects

The objective of the present study was to explore the relationship between basal metabolic rate (BMR), gender, age, anthropometric characteristics, and body composition in severely obese white subjects. In total, 1,412 obese white children and adolescents (BMI > 97° percentile for gender and age) and 7,368 obese adults (BMI > 30 kg/m²) from 7 to 74 years were enrolled in this study. BMR was measured using an indirect calorimeter equipped with a canopy and fat free mass (FFM) were obtained using tetrapolar bioelectrical impedance analysis (BIA). Using analysis of covariance, we tested the effect of gender on the relationship between BMR, age, anthropometry, and body composition. In children and adolescents, the predictor × gender interaction was significant in all cases except for FFM × gender. In adults, all predictor × gender interactions were significant. A prediction equation based on body weight (BW), age, and gender had virtually the same accuracy of the one based on FFM, age, and gender to predict BMR in both children and adults (R²_adj = 0.59 and 0.60, respectively). In conclusion, gender was a significant determinant of BMR in children and adolescents but not in adults. Our results support the hypothesis that the age‐related decline in BMR is due to a reduction in FFM. Finally, anthropometric predictors of BMR are as accurate as body composition estimated by BIA.     

The membrane environment of endogenous cellular prion protein in primary rat cerebellar neurons

We studied the membrane environment of cellular prion protein in primary cultured rat cerebellar neurons differentiated in vitro. In these cells, about 45% of total cellular prion protein (corresponding to a 35-fold enrichment) is associated with a low-density, sphingolipid- and cholesterol-enriched membrane fraction, that can be separated by flotation on sucrose gradient. Biotinylation experiments indicated that almost all prion protein recovered in this fraction was exposed at the cell surface. Prion protein was efficiently separated from this fraction by a monoclonal antibody immuno-separation procedure. Under conditions designed to preserve lipid-mediated membrane organization, several proteins were found in the prion protein-enriched membrane domains (i.e. the non-receptor tyrosine kinases Lyn and Fyn and the neuronal glycosylphosphatidylinositol-anchored protein Thy-1). The prion protein-rich membrane domains contained, as well, about 50% of the sphingolipids, cholesterol and phosphatidylcholine present in the sphingolipid-enriched membrane fraction. All main sphingolipids, including sphingomyelin, neutral glycosphingolipids and gangliosides, were similarly enriched in the prion protein-rich membrane domains. Thus, prion protein plasma membrane environment in differentiated neurons resulted to be a complex entity, whose integrity requires a network of lipid-mediated non-covalent interactions.     

Influence of formulation and process parameters on pellet production by powder layering technique

The goal of the present study was to evaluate the influence of the formulation and operating conditions on pellet preparation by pan technique. To this end, a new pelletization process, typified by the application of powdered drug on sugar-based cores using the GS coating system was studied. Inert cores were intermittently treated with micronized drug powder and adhesive solution. This treatment led to the formation of multiple layers of drug particles around an inert core resulting in the production of pellets that can further be coated by different polymers to obtain modified release formulations. Different procedures have been used to evaluate a series of important parameters such as initial core weight; speed of powder application; speed, type, and position of the atomizers; atomization degree: temperature; and air cap. Good yield of drug layering was obtained by adjusting the quantity of both the drug powder to apply and the binder solution. Pellets obtained following the optimal operating conditions (defined in a pre-formulation study) were film coated with the acrylic polymer Eudragit L30D in order to produce a model formulation consisting of enteric polymer-coated pellets containing ibuprofen. During its preparation, the formulation showed no degradation of the drug, moreover, a low percentage of residual humidity was obtained, indicating that this system is very efficient for the production of highly stable formulations. This study showed the good performance of the GS automated pan-coating system in obtaining enteric coated pellets prepared by powder layering technique using aqueous solutions.     

Evidence of the crucial role of the linker domain on the catalytic activity of human topoisomerase I by experimental and simulative characterization of the Lys681Ala mutant

The functional and structural-dynamical properties of the Lys681Ala mutation in the human topoisomerase IB linker domain have been investigated by catalytic assays and molecular dynamics simulation. The mutant is characterized by a comparable cleavage and a strongly reduced religation rate when compared to the wild type protein. The mutant also displays perturbed linker dynamics, as shown by analysis of the principal components of the motion, and a reduced electrostatic interaction with DNA. Inspection of the inter atomic distances in proximity of the active site shows that in the mutant the distance between the amino group of Lys532 side chain and the 5′ OH of the scissile phosphate is longer than the wild type enzyme, providing an atomic explanation for the reduced religation rate of the mutant. Taken together these results indicate the existence of a long range communication between the linker domain and the active site region and points out the crucial role of the linker in the modulation of the catalytic activity.     

Nerve growth factor and tissue repair remodeling: trkA(NGFR) and p75(NTR), two receptors one fate

This review deals with the role of nerve growth factor (NGF) in healing process as a result of injury. The role of both trkA(NGFR) and p75(NTR) specific NGF receptors and their contribution in the complex network of tissue repair process, is discussed and highlighted in view of recent findings. In fact, NGF represents a significant advance in the treatment of etiologically different ulcers (corneal ulcers, pressure ulcers, post-viral infections, chemical burns) and might shorten the recovery process. For these diseases, no specific treatment is actually available. It is reasonable that apart from NGF and/or neurotrophins a different time-course of trkA(NGRF)/p75(NTR) expression, might regulate the final process. In summary, these novel findings on the potential pro-healing capacity of NGF might open new possibilities for this growth factor in modulating the healing processes in several pathological conditions.     

Early alterations induced by carbon tetrachloride in the lipids of the membranes of the endoplasmic reticulum of the liver cell II. Distribution of the alterations in the various lipid fractions

The distribution of carbon tetrachloride-induced alterations of membrane lipids in various fractions of liver microsomal lipids was studied. The chromatographic spot (referred to as the “D” spot in the previous paper [1]) which has been shown to contain the compounds responsible for the diene conjugation absorption [1], was found in the fatty acid methyl esters prepared from the fraction containing phosphatidylethanolamine (PE) and also in those obtained from the fraction containing phosphatidylserine (PS) and phosphatidylinositol (PI). The absorption of conjugated dienes was very marked in PE and less intense in PS and PI. The fatty acid methyl esters prepared from the fraction containing phosphatidylcholine (PC) showed no presence of the “D” spot and minimal absorption of conjugated dienes.A decrease in arachidonic acid content was found in the fraction containing PE, while no change in content of this fatty acid was found in the fraction containing PC. Results similar to those observed for PC were also found for neutral lipids (NL).Analysis of the fatty acid methyl esters of the various lipid fractions by gas-liquid chromatography (GLC) with an electron capture detector (ECD) gave a qualitative index of the free radical attack by CCl₄ metabolites. Quantitative estimation was attained by study of the irreversible binding of ¹⁴C from ¹⁴CCl₄ to the various lipid fractions. It was found that the fraction containing PS had the highest specific activity, while the fraction containing PC had the lowest specific activity of all the phospholipids. Thin layer chromatography (TLC) of the fraction containing PS revealed that only 11% of the radioactivity was associated with the pure PS moiety, while the remainder was associated with uncharacterized lipids (probably oxidation products).The possible relevance of the alterations induced by carbon tetrachloride in the various phospholipid fractions of liver microsomes to functional changes is discussed.     

Enhancement of CRISPR/Cas12a trans-cleavage activity using hairpin DNA reporters

The RNA programmed non-specific (trans) nuclease activity of CRISPR-Cas Type V and VI systems has opened a new era in the field of nucleic acid-based detection. Here, we report on the enhancement of trans-cleavage activity of Cas12a enzymes using hairpin DNA sequences as FRET-based reporters. We discover faster rate of trans-cleavage activity of Cas12a due to its improved affinity (K_m) for hairpin DNA structures, and provide mechanistic insights of our findings through Molecular Dynamics simulations. Using hairpin DNA probes we significantly enhance FRET-based signal transduction compared to the widely used linear single stranded DNA reporters. Our signal transduction enables faster detection of clinically relevant double stranded DNA targets with improved sensitivity and specificity either in the presence or in the absence of an upstream pre-amplification step.