Head movements of the mealworm beetle Tenebrio molitor

Tethered walking imagines of the mealworm beetle Tenebrio molitor wave their heads in random fashion. If a periodic pattern of vertical black and white stripes is rotated around the animal a regular nystagmic head movement is superimposed upon the random waving, the frequency of the latter equals the contrast frequency within large ranges of the angular velocity of the pattern. The nystagmus is inverted: After a short period of tracking, during which the angular velocity of the head is the same as that of the panorama, the head returns slowly toward its normal position according to an exponential-like function. Resting animals do not wave their heads. However, if the above panorama is rotated, the beetle turns its head in the direction of the movement of the panorama and holds it in a side-way position, as long as the rotation is maintained. The angular position reached depends in the same manner on the angular velocity of the panorama as the turning tendency of walking animals established in open loop experiments using the spherical Y-maze method.     

Hypoxic cardiorespiratory reflexes in the facultative air-breathing fish jeju (Hoplerythrinus unitaeniatus): role of branchial O2 chemoreceptors

In one series of experiments, heart frequency (f _H), blood pressure (P _a), gill ventilation frequency (f _R ), ventilation amplitude (V _AMP) and total gill ventilation (V _TOT) were measured in intact jeju (Hoplerythrinus unitaeniatus) and jeju with progressive denervation of the branchial branches of cranial nerves IX (glossopharyngeal) and X (vagus) without access to air. When these fish were submitted to graded hypoxia (water PO₂ ~140, normoxia to 17 mmHg, severe hypoxia), they increased f _R , V _AMP, V _TOT and P _a and decreased f _H. In a second series of experiments, air-breathing frequency (f _RA), measured in fish with access to the surface, increased with graded hypoxia. In both series, bilateral denervation of all gill arches eliminated the responses to graded hypoxia. Based on the effects of internal (caudal vein, 150 μg NaCN in 0.2 mL saline) and external (buccal) injections of NaCN (500 μg NaCN in 1.0 mL water) on f _R , V _AMP, V _TOT, P _a and f _H we conclude that the O₂ receptors involved in eliciting changes in gill ventilation and associated cardiovascular responses are present on all gill arches and monitor the O₂ levels of both inspired water and blood perfusing the gills. We also conclude that air breathing arises solely from stimulation of branchial chemoreceptors and support the hypothesis that internal hypoxaemia is the primary drive to air breathing.     

Assessing the Emergence of Resistance: The Absence of Biological Cost In Vivo May Compromise Fosfomycin Treatments for P. aeruginosa Infections

Background

Fosfomycin is a cell wall inhibitor used efficiently to treat uncomplicated urinary tract and gastrointestinal infections. A very convenient feature of fosfomycin, among others, is that although the expected frequency of resistant mutants is high, the biological cost associated with mutation impedes an effective growth rate, and bacteria cannot offset the obstacles posed by host defenses or compete with sensitive bacteria. Due to the current scarcity of new antibiotics, fosfomycin has been proposed as an alternative treatment for other infections caused by a wide variety of bacteria, particularly Pseudomonas aeruginosa. However, whether fosfomycin resistance in P. aeruginosa provides a fitness cost still remains unknown.

Principal Findings

We herein present experimental evidence to show that fosfomycin resistance cannot only emerge easily during treatment, but that it is also cost-free for P. aeruginosa. We also tested if, as has been reported for other species such as Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis, fosfomycin resistant strains are somewhat compromised in their virulence. As concerns colonization, persistence, lung damage, and lethality, we found no differences between the fosfomycin resistant mutant and its sensitive parental strain. The probability of acquisition in vitro of resistance to the combination of fosfomycin with other antibiotics (tobramycin and imipenem) has also been studied. While the combination of fosfomycin with tobramycin makes improbable the emergence of resistance to both antibiotics when administered together, the combination of fosfomycin plus imipenem does not avoid the appearance of mutants resistant to both antibiotics.

Conclusions

We have reached the conclusion that the use of fosfomycin for P. aeruginosa infections, even in combined therapy, might not be as promising as expected. This study should encourage the scientific community to assess the in vivo cost of resistance for specific antibiotic-bacterial species combinations, and therefore avoid reaching universal conclusions from single model organisms.     

Regulation of the p19Arf/p53 pathway by histone acetylation underlies neural stem cell behavior in senescence‐prone SAMP8 mice

Brain aging is associated with increased neurodegeneration and reduced neurogenesis. B1/neural stem cells (B1‐NSCs) of the mouse subependymal zone (SEZ) support the ongoing production of olfactory bulb interneurons, but their neurogenic potential is progressively reduced as mice age. Although age‐related changes in B1‐NSCs may result from increased expression of tumor suppressor proteins, accumulation of DNA damage, metabolic alterations, and microenvironmental or systemic changes, the ultimate causes remain unclear. Senescence‐accelerated‐prone mice (SAMP8) relative to senescence‐accelerated‐resistant mice (SAMR1) exhibit signs of hastened senescence and can be used as a model for the study of aging. We have found that the B1‐NSC compartment is transiently expanded in young SAMP8 relative to SAMR1 mice, resulting in disturbed cytoarchitecture of the SEZ, B1‐NSC hyperproliferation, and higher yields of primary neurospheres. These unusual features are, however, accompanied by premature loss of B1‐NSCs. Moreover, SAMP8 neurospheres lack self‐renewal and enter p53‐dependent senescence after only two passages. Interestingly, in vitro senescence of SAMP8 cells could be prevented by inhibition of histone acetyltransferases and mimicked in SAMR1 cells by inhibition of histone deacetylases (HDAC). Our data indicate that expression of the tumor suppressor p19, but not of p16, is increased in SAMP8 neurospheres, as well as in SAMR1 neurospheres upon HDAC inhibition, and suggest that the SAMP8 phenotype may, at least in part, be due to changes in chromatin status. Interestingly, acute HDAC inhibition in vivo resulted in changes in the SEZ of SAMR1 mice that resembled those found in young SAMP8 mice.     

Implications for human adipose‐derived stem cells in plastic surgery

Adipose‐derived stem cells (ADSCs) are a subset of mesenchymal stem cells (MSCs) that possess many of the same regenerative properties as other MSCs. However, the ubiquitous presence of ADSCs and their ease of access in human tissue have led to a burgeoning field of research. The plastic surgeon is uniquely positioned to harness this technology because of the relative frequency in which they perform procedures such as liposuction and autologous fat grafting. This review examines the current landscape of ADSC isolation and identification, summarizes the current applications of ADSCs in the field of plastic surgery, discusses the risks associated with their use, current barriers to universal clinical translatability, and surveys the latest research which may help to overcome these obstacles.     

A protein aggregation based test for screening of the agents affecting thermostability of proteins

To search for agents affecting thermal stability of proteins, a test based on the registration of protein aggregation in the regime of heating with a constant rate was used. The initial parts of the dependences of the light scattering intensity (I) on temperature (T) were analyzed using the following empiric equation: I = K _agg(T−T ₀)², where K _agg is the parameter characterizing the initial rate of aggregation and T ₀ is a temperature at which the initial increase in the light scattering intensity is registered. The aggregation data are interpreted in the frame of the model assuming the formation of the start aggregates at the initial stages of the aggregation process. Parameter T ₀ corresponds to the moment of the origination of the start aggregates. The applicability of the proposed approach was demonstrated on the examples of thermal aggregation of glycogen phosphorylase b from rabbit skeletal muscles and bovine liver glutamate dehydrogenase studied in the presence of agents of different chemical nature. The elaborated approach to the study of protein aggregation may be used for rapid identification of small molecules that interact with protein targets.     

Cellular senescence and autophagy of myoepithelial cells are involved in the progression of in situ areas of carcinoma ex-pleomorphic adenoma to invasive carcinoma. An in vitro model

During tumor invasion, benign myoepithelial cells of carcinoma ex-pleomorphic adenoma (CXPA) surround malignant epithelial cells and disappear. The mechanisms involved in the death and disappearance of these myoepithelial cells were investigated via analysis of the expression of regulatory proteins for apoptosis, autophagy and cellular senescence in an in situ in vitro model. Protein expression relating to apoptosis (Bax, Bcl-2, Survivin), autophagy (Beclin-1, LC3B) and cellular senescence (p21, p16) was evaluated using indirect immunofluorescence. β-galactosidase expression was assessed via histochemistry. Biopsies of CXPA (ex vivo) allowed immunhistochemical evaluation of p21 and p16, whilst LC3B, p21 and p16 protein expression was analyzed by western blotting. In the in vitro model, the myoepithelial cells were positive for LC3B (cytoplasm) and p21 (nucleus), whilst in vivo positivity for p21 and p16 was observed. In vitro, β-galactosidase activity increased in the myoepithelial cells over time. Western blotting analysis revealed an increased LC3B, p16 and p21 expression in the myoepithelial cells with previous contact with the malignant cells when compared with those without contact. The investigation of behavior of benign myoepithelial cells in ductal areas of CXAP revealed that the myoepithelial cells are involved in the autophagy-senescence phenotype that subsequently leads to their disappearance.     

Socioeconomic Factors and Cultural Changes Explain the Knowledge and Use of Ouricuri Palm (Syagrus coronata) by the Fulni–ô Indigenous People of Northeast Brazil

Economic Botany - Socioeconomic Factors and Cultural Changes Explain the Knowledge and Use of Ouricuri Palm (Syagrus coronata) by the Fulni–ô Indigenous People of Northeast...     

New insights into the properties of pubescent surfaces: peach fruit as a model

The surface of peach (Prunus persica 'Calrico') is covered by a dense indumentum, which may serve various protective purposes. With the aim of relating structure to function, the chemical composition, morphology, and hydrophobicity of the peach skin was assessed as a model for a pubescent plant surface. Distinct physicochemical features were observed for trichomes versus isolated cuticles. Peach cuticles were composed of 53% cutan, 27% waxes, 23% cutin, and 1% hydroxycinnamic acid derivatives (mainly ferulic and p-coumaric acids). Trichomes were covered by a thin cuticular layer containing 15% waxes and 19% cutin and were filled by polysaccharide material (63%) containing hydroxycinnamic acid derivatives and flavonoids. The surface free energy, polarity, and work of adhesion of intact and shaved peach surfaces were calculated from contact angle measurements of water, glycerol, and diiodomethane. The removal of the trichomes from the surface increased polarity from 3.8% (intact surface) to 23.6% and decreased the total surface free energy chiefly due to a decrease on its nonpolar component. The extraction of waxes and the removal of trichomes led to higher fruit dehydration rates. However, trichomes were found to have a higher water sorption capacity as compared with isolated cuticles. The results show that the peach surface is composed of two different materials that establish a polarity gradient: the trichome network, which has a higher surface free energy and a higher dispersive component, and the cuticle underneath, which has a lower surface free energy and higher surface polarity. The significance of the data concerning water-plant surface interactions is discussed within a physiological context.     

Skeletal ossification and sequence heterochrony in xenarthran evolution

Previous analyses of how mammals vary in their ossification sequences have focused on monotremes, marsupials, and boreoeutherian placentals. Here, we focus on the sequence of cranial and postcranial ossification events during growth in the xenarthran skull and skeleton, including armadillos, anteaters, and sloths. We use two different methods to quantify sequence heterochrony: sequence analysis of variance (ANOVA) and event‐paring/Parsimov. Our results indicate that Parsimov is conservative and does not detect clear heterochronic shifts between xenarthran and boreoeutherian placentals. Sequence‐ANOVA performs better, but both methods exhibit sensitivity to the artifactual accumulation of ties. By controlling for ties and taking into account results that the methods have in common, our analysis suggests that xenarthrans significantly differ from other placentals by a late ossification of the sternum and an early ossification of the phalanges and pubis. We interpret these differences as showing that heterochrony plays a role in the skeletal development of xenarthrans, a change from previous studies that have emphasized the developmental homogeneity of the skeleton across placental mammals.