Functional analysis of a fatty acid binding protein produced by Aphidius ervi teratocytes

Aphidius ervi (Hymenoptera, Braconidae) is an endophagous parasitoid of various aphid species, including Acyrthosiphon pisum (Homoptera, Aphididae), the model host used in the present study. Parasitized hosts show a marked increase of their nutritional suitability for the developing parasitoid larvae. This alteration of the biochemical and metabolic profile is due to a castration process mediated by the combined action of the venom, injected at the oviposition, and of the teratocytes, cells deriving from the dissociation of the embryonic membrane. Teratocytes produce and release in the host haemocoel two parasitism-specific proteins, which are of crucial importance for the development of their sister larvae. One of the proteins is a fatty acid binding protein (Ae-FABP), which shows a high affinity for C14-C18 saturated fatty acids (FAs) and for oleic and arachidonic acids. To better define the possible nutritional role of this protein, we have studied its immunolocalization profile in vivo and the impact on FA uptake by the epidermal and midgut epithelia of A. ervi larvae. During the exponential growth of A. ervi larvae, Ae-FABP is distributed around discrete lipid particles, which are abundantly present in the haemocoel of parasitized host aphids and in the midgut lumen of parasitoid larvae. Moreover, a strong immunodetection signal is evident on the surface of the two larval epithelia involved in nutrient absorption: the parasitoid midgut epithelium and the external epidermal layer. These two epithelia can effectively absorb radiolabelled myristic acid, but the FA transport rates are not affected by the presence in the medium of Ae-FABP. The protein appears to act essentially as a vector in the host haemolymph, transferring FAs from the digestion sites of host lipids to the growing parasitoid larvae. These data indicate that the proteins produced by A. ervi teratocytes may play complementary roles in the nutritional exploitation of the host.     

Mitochondrial diabetes in children: seek and you will find it

Maternally Inherited Diabetes and Deafness (MIDD) is a rare form of diabetes due to defects in mitochondrial DNA (mtDNA). 3243 A>G is the mutation most frequently associated with this condition, but other mtDNA variants have been linked with a diabetic phenotype suggestive of MIDD. From 1989 to 2009, we clinically diagnosed mitochondrial diabetes in 11 diabetic children. Diagnosis was based on the presence of one or more of the following criteria: 1) maculopathy; 2) hearing impairment; 3) maternal heritability of diabetes/impaired fasting glucose and/or hearing impairment and/or maculopathy in three consecutive generations (or in two generations if 2 or 3 members of a family were affected). We sequenced the mtDNA in the 11 probands, in their mothers and in 80 controls. We identified 33 diabetes-suspected mutations, 1/33 was 3243A>G. Most patients (91%) and their mothers had mutations in complex I and/or IV of the respiratory chain. We measured the activity of these two enzymes and found that they were less active in mutated patients and their mothers than in the healthy control pool. The prevalence of hearing loss (36% vs 75-98%) and macular dystrophy (54% vs 86%) was lower in our mitochondrial diabetic adolescents than reported in adults. Moreover, we found a hitherto unknown association between mitochondrial diabetes and celiac disease. In conclusion, mitochondrial diabetes should be considered a complex syndrome with several phenotypic variants. Moreover, deafness is not an essential component of the disease in children. The whole mtDNA should be screened because the 3243A>G variant is not as frequent in children as in adults. In fact, 91% of our patients were mutated in the complex I and/or IV genes. The enzymatic assay may be a useful tool with which to confirm the pathogenic significance of detected variants.     

Autophagy precedes apoptosis during the remodeling of silkworm larval midgut

Although several features of apoptosis and autophagy have been reported in the larval organs of Lepidoptera during metamorphosis, solid experimental evidence for autophagy is still lacking. Moreover, the role of the two processes and the nature of their relationship are still cryptic. In this study, we perform a cellular, biochemical and molecular analysis of the degeneration process that occurs in the larval midgut of Bombyx mori during larval-adult transformation, with the aim to analyze autophagy and apoptosis in cells that die under physiological conditions. We demonstrate that larval midgut degradation is due to the concerted action of the two mechanisms, which occur at different times and have different functions. Autophagy is activated from the wandering stage and reaches a high level of activity during the spinning and prepupal stages, as demonstrated by specific autophagic markers. Our data show that the process of autophagy can recycle molecules from the degenerating cells and supply nutrients to the animal during the non-feeding period. Apoptosis intervenes later. In fact, although genes encoding caspases are transcribed at the end of the larval period, the activity of these proteases is not appreciable until the second day of spinning and apoptotic features are observable from prepupal phase. The abundance of apoptotic features during the pupal phase, when the majority of the cells die, indicates that apoptosis is actually responsible for cell death and for the disappearance of larval midgut cells.     

The role of gut hormones in controlling the food intake. What is their role in emerging diseases?

Central nervous system (CNS) receives peripheral relevant information that are able to regulate individual's energy balance through metabolic, neural, and endocrine signals. Ingested nutrients come into contact with multiple sites in the gastrointestinal tract that have the potential to alter peptide and neural signaling. There is a strong relationship between CNS and those peripheral signals (as gastrointestinal hormones) in the control of food intake. The purpose of this review is to give updated information about the role of gut hormones as mediators of feeding behavior and of different nutrients in modulating gut hormones production. The role of gut hormones in the pathogenesis of emerging diseases as obesity and non-alcoholic fatty liver disease (NAFLD) is also discussed together with the possible role of these peripheral signals as targets of future therapeutic options.     

Pendrin in the mouse kidney is primarily regulated by Cl- excretion but also by systemic metabolic acidosis

The Cl(-)/anion exchanger pendrin (SLC26A4) is expressed on the apical side of renal non-type A intercalated cells. The abundance of pendrin is reduced during metabolic acidosis induced by oral NH(4)Cl loading. More recently, it has been shown that pendrin expression is increased during conditions associated with decreased urinary Cl(-) excretion and decreased upon Cl(-) loading. Hence, it is unclear if pendrin regulation during NH(4)Cl-induced acidosis is primarily due the Cl(-) load or acidosis. Therefore, we treated mice to increase urinary acidification, induce metabolic acidosis, or provide an oral Cl(-) load and examined the systemic acid-base status, urinary acidification, urinary Cl(-) excretion, and pendrin abundance in the kidney. NaCl or NH(4)Cl increased urinary Cl(-) excretion, whereas (NH(4))(2)SO(4), Na(2)SO(4), and acetazolamide treatments decreased urinary Cl(-) excretion. NH(4)Cl, (NH(4))(2)SO(4), and acetazolamide caused metabolic acidosis and stimulated urinary net acid excretion. Pendrin expression was reduced under NaCl, NH(4)Cl, and (NH(4))(2)SO(4) loading and increased with the other treatments. (NH(4))(2)SO(4) and acetazolamide treatments reduced the relative number of pendrin-expressing cells in the collecting duct. In a second series, animals were kept for 1 and 2 wk on a low-protein (20%) diet or a high-protein (50%) diet. The high-protein diet slightly increased urinary Cl(-) excretion and strongly stimulated net acid excretion but did not alter pendrin expression. Thus, pendrin expression is primarily correlated with urinary Cl(-) excretion but not blood Cl(-). However, metabolic acidosis caused by acetazolamide or (NH(4))(2)SO(4) loading prevented the increase or even reduced pendrin expression despite low urinary Cl(-) excretion, suggesting an independent regulation by acid-base status.     

Engraftment and differentiation of neocortical progenitor cells transplanted to the embryonic brain in utero

Transplantation of neural progenitors or stem cells is a most useful tool to investigate the relative contribution of cell-autonomous mechanisms and environmental cues in the regulation of cell specification and differentiation during CNS development. To assess the capability of neocortical progenitor cells to integrate into foreign brain regions, here we examined the fate of precursor cells isolated from the dorsal telencephalon of E12 ß-actin-EGFP transgenic mouse embryos after heterotopic/heterochronic transplantation to the E16 rat brain in utero. Our observations show that donor cells were able to penetrate, survive and produce mature cell types into wide regions of the host CNS. Namely, EGFP-positive cells acquired site-specific neuronal identities in many telencephalic regions, including neocortex, hippocampus, olfactory bulb and corpus striatum. In contrast, incorporation into more caudal sites was much less efficient. A fraction of donor cells formed large aggregates that remained segregated from the host milieu. Such aggregates contained mature neurons and glia, including some EGFP-negative elements of host origin, and developed the complex organization of the mature nervous tissue. On the other hand, transplanted cells that engrafted in the parenchyma of extratelencephalic regions predominantly generated glial types. The few neurons failed to acquire obvious site-specific phenotypic traits and did not integrate into the local host architecture. Altogether, our observations indicate that E12 neocortical progenitors are already committed towards regional identities and are unable to modify their phenotypic choices when exposed to heterotopic environmental conditions along different rostro-caudal domains of the embryonic CNS.     

Further Data on the Mediterranean Sea Tardigrade Fauna

Available information about Mediterranean tardigrades regards mainly the insular and peninsular Italian coasts, but also Malta, the Alboran Sea, Spain, France, Albania, Morocco, Algeria, Tunisia, Cyprus, and Lebanon. The Mediterranean Tardigrades, more than 70 species, are Heterotardigrada, mainly the order Arthrotardigrada with several families, and the order Echiniscoidea with only the family Echiniscoididae. Coralligenous detritus seems to be the most favourable kind of sediment in which the highest values of biodiversity are reached. Halechiniscidae is the most important family in the subtidal zone, whereas Batillipedidae are more frequent in the intertidal zone. A study of 4 submarine cave populations has been carried out. Neoarctidae and Neostygarctidae, considered as the most ancient families, have only been found in the Mediterranean Sea to date. This could mean that Arthrotardigrada originated in the old Thetys Sea from which the basin of the Mediterranean Sea was formed.