Evolutionary trend of Zoophycos morphotypes from the Upper Cretaceous–Lower Miocene in the type pelagic sections of Gubbio,Italy

About 200 Zoophycos specimens, including 90 specimens studied in detail, have been analysed in the continuous Upper Cretaceous–Lower Miocene pelagic sedimentary type sections of the Gubbio area (the Contessa Highway, Contessa Quarry and Bottaccione sections, Northern Apennines). The sediments are reddish to grey limestones and marls of the Scaglia Group and marls with volcaniclastic deposits of the Bisciaro Formation. The aim was to examine the evolutionary trend of what is probably the most debated trace fossil of all time, from the Upper Cretaceous to Lower Miocene. Despite having been found in beds ranging from the Cambrian to the present, no consensus has been reached regarding mode of construction, tracemaker or ethological explanation for Zoophycos. Four Zoophycos morphotypes are recognized at Gubbio showing variations of major and minor lamellae, apex, lobes and whorls: the Cretaceous–Eocene cone‐shaped type 1, the Upper Eocene–Middle Oligocene helicoidal type 2, the Oligocene lobate type 3 and the Upper Oligocene–Lower Miocene flat type 4. The very high ichnodensity in some beds (hundreds of specimens in discrete levels of the Bisciaro Formation, now destroyed by quarrying) seems to find explanation in abnormal concentrations of phytodetritus and organic matter on the seafloor in some periods. This very high abundance in discrete levels reflects a change in sedimentation and seafloor conditions at pre‐flysch deposition. Due to such high ichnodensity, many adjacent specimens display deformed outer margins. Taphonomic analysis shows a variation of whorls, laminae and U‐shaped lobes, reflecting ontogenetic development of the tracemaker(s) (?sipunculid worms).     

The effect of bioturbation by polychaetes (Opheliidae) on benthic foraminiferal assemblages and test preservation

Biological activity such as burrowing can alter benthic foraminiferal shell preservation and may also modify benthic foraminiferal assemblages by vertical mixing, inducing sediment homogenization. Here, we analyse benthic foraminiferal assemblages and taphonomy of upper Miocene marine deposits from Conil de la Frontera (Cádiz, south‐western Spain). The deposits consist of marls displaying a pervasive alternation of intensively bioturbated beds dominated by Macaronichnus segregatis traces (ichnofabric index 4–5) and non‐bioturbated beds. Benthic foraminiferal assemblages are dominated by Cibicidoides mundulus and Cibicides refulgens, indicating that the marls were deposited on an oligotrophic, well‐oxygenated upper slope. The impact of burrowing on the preservation of benthic foraminiferal tests was tested using Q‐mode cluster analysis, which found two well‐differentiated groups of samples, one including the non‐bioturbated beds and the other encompassing the bioturbated ones. Fragmentation and recrystallization account for the differentiation of these groups, both being higher in the bioturbated sediments. Aggressive chemical digestion by the Macaronichnus trace‐makers, assumed to be a polychaete worm of the family Opheliidae, etched the microfossil shells, making them more vulnerable to fragmentation. Intense bioturbation favoured the circulation of pore fluids, encouraging recrystallization. Pervasive burrowing resulted in significant vertical reworking of microfossils. As a consequence, benthic foraminiferal assemblages in the bioturbated beds were homogenized in the mixed layer; that is, the uppermost layer of the substrate totally burrowed. The alternation of bioturbated and non‐bioturbated beds reflects episodic transfer of food particles down slope from shallower parts of the shelf as well as from the continent due to storms under otherwise homogeneous oligotrophic marine conditions.     

Intake and digestion of horned guan Oreophasis derbianus diets measured in three Mexican zoos

We conducted nutritional analyses of diets offered to and ingested by seven pairs of horned guans (Oreophasis derbianus) in three zoos. Digestibility was calculated with individually housed birds (n=1 at each zoo). Diets offered varied widely among institutions, both in ingredients fed as well as in nutrient composition. Feeding selectivity was evident through differences in composition of diets offered vs. consumed, with fruit (bananas, grape, and/or plantain) and avocado (when offered) highly preferred; green leaves, poultry pellets, and other vegetables comprised lesser proportions of the diet. All facilities fed 2–3X more food than consumed, allowing a great degree of choice of preferred items and potentially consumption of nutritionally imbalanced diets—in particular, mineral constituents. Diets were highly digestible; dry matter (DM) digestion coefficients ranged from 70 to ∼90%; protein digestibility varied from 30 to 80%; fat was >90% digestible. Diet composition was compared with known nutritional requirements of domestic avian species, and feeding recommendations discussed. Despite the wide variability in nutrient composition of diets eaten (i.e. protein 6–10% of DM; fat 2–17% of DM), no overt health problems were noted and all pairs had successfully reproduced on these diets. It is suggested that horned guans may have nutrient requirements more similar to those suggested for other frugivorous birds than values determined for poultry as the physiologic model. Comparisons with native food items, as well as more detailed nutrient balance studies, may provide even better guidelines for captive management of this highly endangered species. Zoo Biol 28:319–330, 2009. © 2009 Wiley-Liss, Inc.     

The role of dietary protein on lipotoxicity

Lipotoxicity is a metabolic abnormality frequently observed during the development of obesity and is the main cause of several changes in the metabolic observed during metabolic syndrome. Consistent consumption of diets high in saturated fat or simple carbohydrates combined with low physical activity are the main causes of obesity and its comorbidities. However, the contribution of dietary protein and, in particular, the contribution due to the type of dietary protein, to the process of obesity and its metabolic consequences are less well-understood. In this review, we showed that the type of dietary protein has a significant contribution to the process of lipotoxicity through the modulation of insulin secretion and the regulation of adipocyte metabolic function. Consumption of soy protein stimulates insulin secretion to a lower extent than casein despite the fact that both are high-quality proteins. The amino acid profiles of soy protein and its isoflavones are responsible for the reduced insulin secretion. Also, soy protein increases insulin sensitivity, whereas casein has the opposite effect. Consequently, soy protein reduces SREBP-1 expression in the liver leading to low accumulation of hepatic triglycerides, despite the consumption of a high-fat diet. Furthermore, soy protein reduces adipocyte hypertrophy, hyperleptinemia, and free fatty acid concentration. Thus, the influx of FA into the liver decreases, and hepatic oxidation of FA increases. These metabolic changes result in a decrease in lipid depots and ceramide which reduce hepatic lipotoxicity, whereas casein produces the opposite effect. This study emphasizes that the type of dietary protein has an important effect on lipotoxicity.     

Ectopic expression of tyrosine hydroxylase in the pigmented epithelium rescues the retinal abnormalities and visual function common in albinos in the absence of melanin

Albino mammals have profound retinal abnormalities, including photoreceptor deficits and misrouted hemispheric pathways into the brain, demonstrating that melanin or its precursors are required for normal retinal development. Tyrosinase, the primary enzyme in melanin synthesis commonly mutated in albinism, oxidizes l-tyrosine to l-dopaquinone using l-3,4-dihydroxyphenylalanine (L-DOPA) as an intermediate product. L-DOPA is known to signal cell cycle exit during retinal development and plays an important role in the regulation of retinal development. Here, we have mimicked L-DOPA production by ectopically expressing tyrosine hydroxylase in mouse albino retinal pigment epithelium cells. Tyrosine hydroxylase can only oxidize l-tyrosine to L-DOPA without further progression towards melanin. The resulting transgenic animals remain phenotypically albino, but their visual abnormalities are corrected, with normal photoreceptor numbers and hemispheric pathways and improved visual function, assessed by an increase of spatial acuity. Our results demonstrate definitively that only early melanin precursors, L-DOPA or its metabolic derivatives, are vital in the appropriate development of mammalian retinae. They further highlight the value of substituting independent but biochemically related enzymes to overcome developmental abnormalities.     

Some Characteristics of Threonine Transport Across the Blood-Brain Barrier of the Rat

Threonine entry into brain is altered by diet-induced changes in concentrations of plasma amino acids, especially the small neutrals. To study this finding further, we compared effects of various amino acids (large and small neutrals, analogues, and transport models) on transport of threonine and phenylalanine across the blood-brain barrier. Threonine transport was saturable and was usually depressed more by natural large than small neutrals. Norvaline and 2-amino-n-butyrate (AABA) were stronger competitors than norleucine. 2-Aminobicyclo[2.2.1]heptane-2-carboxylate (BCH), a model in other preparations for the large neutral (L) system, and cysteine, a proposed model for the ASC system only in certain preparations, reduced threonine transport; 2-(methylamino)isobutyrate (MeAIB; a model for the A system for small neutrals) did not. Phenylalanine transport was most depressed by cold phenylalanine and other large neutrals; threonine and other small neutrals had little effect. Norleucine, but not AABA, was a strong competitor; BCH was more competitive than cysteine or MeAIB. Absence of sodium did not affect phenylalanine transport, but decreased threonine uptake by 25% (p less than 0.001). Our results with natural, analogue, and model amino acids, and especially with sodium, suggest that threonine, but not phenylalanine, may enter the brain partly by the sodium-dependent ASC system.     

Detection of four human milk groups with respect to Lewis blood group dependent oligosaccharides

Neutral oligosaccharides in human milk samples from approximately 50 women were analysed applying a recently developed high-pH anion-exchange chromatographic method. Three different oligosaccharide patterns could be detected in accordance with milk groups that had been already described. These oligosaccharide groups correspond to the Lewis blood types Le(a−b+), Le(a+b−) and Le(a−b−). In addition to these oligosaccharide patterns, a new carbohydrate pattern was detected in a milk sample from a Le(a−b−) individual. Here, only nonfucosylated oligosaccharides and compounds bearing a1,3 linked fucosyl residues were found, whereas structures with a1,2 and a1,4 fucosyl linkages were missing. This finding led to the hypothesis that there are four different oligosaccharide milk groups that fit well to the genetic basis of the Lewis blood group system. This revised version was published online in November 2006 with corrections to the Cover Date.     

Extrachromosomal, homologous expression of trypanothione reductase and its complementary mRNA in Trypanosoma cruzi.

Trypanothione reductase (TR), a flavoprotein oxidoreductase present in trypanosomatids but absent in human cells, is regarded as a potential target for the chemotherapy of several tropical parasitic diseases caused by trypanosomes and leishmanias. We investigated the possibility of modulating intracellular TR levels in Trypanosoma cruzi by generating transgenic lines that extrachromosomally overexpress either sense or antisense TR mRNA. Cells overexpressing the sense construct showed a 4-10-fold increase in levels of TR mRNA, protein and enzyme activity. In contrast, recombinant T.cruzi harbouring the antisense construct showed no significant difference in TR protein or catalytic activity when compared with control cells. Although increased levels of TR mRNA were detected in some of the antisense cells neither upregulation nor amplification of the endogenous trypanothione reductase gene (tryA) was observed. Instead, a proportion of plasmid molecules was found rearranged and, as a result, contained the tryA sequence in the sense orientation. Plasmid rescue experiments and sequence analysis of rearranged plasmids revealed that this specific gene inversion event was associated with the deletion of small regions of flanking DNA.     

Population genetics and symbiont assemblages support opposing invasion scenarios for the red turpentine beetle (Dendroctonus valens)

Exotic forest insects and their symbionts pose an increasing threat to forest health. This is apparently true for the red turpentine beetle (Dendroctonus valens), which was unintentionally introduced to China, where the beetle has killed millions of healthy native pine trees. Previous population genetics studies that used cytochrome oxidase I as a marker concluded that the source of D. valens in China was western North America. In contrast, surveys of fungi associated with D. valens demonstrated that more fungal species are shared between China and eastern North America than between China and western North America, suggesting that the source population of D. valens could be eastern North America. In this study, we used microsatellite markers to determine population structure of D. valens in North America as well as the source population of the beetle in China. The analyses revealed that four genetically distinct populations (herein named the West, Central, Northeast and Mexico) represent the native range of D. valens. Clustering analyses and a simulation‐based approximate Bayesian computation (ABC) approach supported the hypothesis that western North America is the source of the invasive D. valens population. This study provides a demonstration of non‐congruence between patterns inferred by studies on population genetics and symbiont assemblages in an invasive bark beetle.