Conservation of Latin America freshwater biodiversity: beyond political borders

Biodiversity and Conservation - Latin America’s tremendous socio-cultural and biological diversity has evolved along tightly intertwined, far-reaching river networks. Decisions taken by any...     

Effect of intracerebroventricular injection of histamine on the behavior of the white rat

Previous references showed that the histamine injected peripherically produced a deterioration of the learning in experimental animals. The effects of 100 and 200 micrograms of histamine administered in the cerebral lateral ventricle, have been tested using an experimental paradigm which isolated attentional, motivational, and motor factor from the complex learned behavior. The obtained results showed to be similar to those produced by peripheric injection, and demonstrated a worsening in attentional, motivational, and motor parameters.     

Fertility changes in surface waters during the Aalenian (mid-Jurassic) of the Western Tethys as revealed by calcareous nannofossils and carbon-cycle perturbations

In Aalenian times, the South Iberian Palaeomargin was part of the westernmost Tethys Ocean. The Median Subbetic palaeogeographic domain of the Betic Cordillera was a relatively deep trough in the South Iberian Palaeomargin during the Early Jurassic–Late Cretaceous interval, where mainly pelagic and hemipelagic limestones and marls were deposited. A semiquantitative study of nannofossil assemblages was performed in sediments from the upper Toarcian–lowest Bajocian from two Median Subbetic sections (Agua Larga and Cerro de Mahoma). Nannofossil assemblages are composed mainly of cosmopolitan and Tethyan taxa. The NJ8a, NJ8b and NJ9 Zones as well as other useful biohorizons (FOs of Triscutum tiziense and Carinolithus magharensis and LO of Similiscutum finchii) were identified and directly correlated to ammonite zones. The analysis of the relative abundances of some common to abundant taxa including Biscutum, Carinolithus superbus, Crepidolithus crassus, Lotharingius, Schizosphaerella and Watznaueria display noticeable fluctuations that can be correlated between the two sections. The comparison of these fluctuations with the δ¹³C_carb curves and the interpretation of the palaeoecologic significance of some of these taxa provided an outline of the palaeoceanographic trophic regime throughout the interval studied. During the latest Toarcian–Early Aalenian, the high proportions of oligotrophic Schizosphaerella, moderately high proportions of C. crassus and low proportions of eutrophic Biscutum, correlate with low to moderate values in the δ¹³C_carb curves. Radiolarians display low abundance throughout this interval. This is interpreted as an interval where mesotrophic to oligotrophic and stable conditions occurred in surface waters. The Middle Aalenian, characterized by high proportions of Schizosphaerella and C. crassus and low proportions of Biscutum, correlates with low values in the δ¹³C_carb curves, and was interpreted to correspond to an episode when stable oligotrophic conditions occurred in surface waters. Radiolarians moderately increased throughout this interval. Finally, the Late Aalenian–earliest Bajocian interval, with lower proportions of Schizosphaerella and C. crassus, and higher proportions of Biscutum, also correlates with a significant positive excursion in the δ¹³C_carb curve, suggesting a shift from oligo- to eutrophic conditions in surface waters. This change in productivity is also revealed by a conspicuous increase in radiolarian abundance, at the same time as a quasi-complete replacement of Early Jurassic radiolarian fauna took place. The analysis of faunal-flora turnovers reveals a causal link between the global carbon-cycle and the pelagic response. This noticeable faunal-flora change throughout the Late Aalenian–Bajocian can be interpreted as a major biological response to the drastic modification in the western Tethys palaeogeography as consequence of the Atlantic opening, which in turn caused a new pattern in the oceanic circulation.     

5-Keto-D-fructose production from sugar alcohol by isolated wild strain Gluconobacter frateurii CHM 43

ABSTRACT

Gluconobacter frateurii CHM 43 have D-mannitol dehydrogenase (quinoprotein glycerol dehydrogenase) and flavoprotein D-fructose dehydrogenase in the membranes. When the two enzymes are functional, D-mannitol is converted to 5-keto-D-fructose with 65% yield when cultivated on D-mannitol. 5-Keto-D-fructose production with almost 100% yield was realized with the resting cells. The method proposed here should give a smart strategy for 5-keto-D-fructose production.