Geochemical study of vertebrate fossils from the Upper Cretaceous (Santonian) Csehbánya Formation (Hungary): Evidence for a freshwater habitat of mosasaurs and pycnodont fish

The diverse vertebrate remains from the Upper Cretaceous freshwater settings at Iharkút, Hungary, contain two fossil groups, Pycnodontiformes fish and Mosasauridae that are almost exclusively known from marine palaeo-environments. Hence, their appearance in alluvial sediments is very unusual. Trace element and isotope compositions of the remains have been analyzed to investigate the taphonomy and the ecological differences among the different fossil groups present at Iharkút.All examined fossils have undergone post-depositional diagenetic alteration, which resulted in high concentrations of REE, U, and Fe, together with almost complete homogenization of δ¹⁸O_CO3 values. Similar REE patterns in different fossils suggest a common origin for all remains, hence the discovered species most likely lived in the same local ecosystem. Despite partial diagenetic overprinting, the δ¹⁸O_PO4 values of the fossils indicate sufficient taxon-specific isotopic diversity to permit some broad conclusions on the palaeo-environment of the fossils. In particular, it is apparent that the isotopic composition of the Pycnodontiformes fish and Mosasauridae remains is most compatible with a freshwater palaeo-habitat and incompatible with a marine palaeo-environment. In addition, the Sr concentration and isotope data indicate that the Pycnodontiformes and Mosasauridae likely lived predominantly in a freshwater environment and were not simply occasional visitors to the Iharkút river ecosystem.Regarding other fossil groups, high δ¹⁸O_PO4 values of Alligatoroidea and Iharkutosuchus teeth suggest that these small crocodile species might have inhabited swamps and ponds where the water was relatively rich in ¹⁸O due to evaporation.     

Substrate specificity of a glucose-6-phosphate isomerase from <Emphasis Type="Italic">Pyrococcus furiosus</Emphasis> for monosaccharides

We purified recombinant glucose-6-phosphate isomerase from Pyrococcus furiosus using heat treatment and Hi-Trap anion-exchange chromatography with a final specific activity of 0.39 U mg⁻¹. The activity of the glucose-6-phosphate isomerase for l-talose isomerization was optimal at pH 7.0, 95°C, and 1.5 mM Co²⁺. The half-lives of the enzyme at 65°C, 75°C, 85°C, and 95°C were 170, 41, 19, and 7.9 h, respectively. Glucose-6-phosphate isomerase catalyzed the interconversion between two different aldoses and ketose for all pentoses and hexoses via two isomerization reactions. This enzyme has a unique activity order as follows: aldose substrates with hydroxyl groups oriented in the same direction at C2, C3, and C4 > C2 and C4 > C2 and C3 > C3 and C4. l-Talose and d-ribulose exhibited the most preferred substrates among the aldoses and ketoses, respectively. l-Talose was converted to l-tagatose and l-galactose by glucose-6-phosphate isomerase with 80% and 5% conversion yields after about 420 min, respectively, whereas d-ribulose was converted to d-ribose and d-arabinose with 53% and 8% conversion yields after about 240 min, respectively.     

Complete allocation sampling: an efficient and easily implemented adaptive sampling design

Adaptive sampling designs are becoming increasingly popular in environmental science, particularly for surveying rare and aggregated populations. An adaptive sample is one in which the survey design is modified, or adapted, in some way on the basis of information gained during the survey. There are many different adaptive survey designs that can be used to estimate animal and plant abundance. In adaptive cluster sampling, additional sample effort is allocated during the survey to the immediate neighborhood in which the species is found. In adaptive stratified sampling, additional sample effort is allocated during the survey to strata of high abundance. The appealing feature of these adaptive designs is that the field biologist gets to do what innately seems sensible when working with rare and aggregated populations—field effort is targeted around where the species is observed in the first wave of the survey. However, there are logistical challenges of applying this principle of targeted field effort while remaining in the framework of probability-based sampling. We propose a simplified adaptive survey design that incorporates both targeting field effort and being logistically feasible. We show with a case study population of rockfish that complete allocation stratified sampling is a very efficient design.     

Development of high-throughput spermidine synthase activity assay using homogeneous time-resolved fluorescence

Spermidine synthase (SPDS) catalyzes transfer of the propylamine group from decarboxylated S-adenosylmethionine (dcSAM) to putrescine to yield methylthioadenosine (MTA) and spermidine. SPDS plays a regulatory role in cell proliferation and differentiation. This article describes the development of a high-throughput SPDS activity assay using homogeneous time-resolved fluorescence (HTRF) based on energy transfer from europium cryptate as a donor to crosslinked allophycocyanin (XL665) as an acceptor. First a highly specific anti-MTA monoclonal antibody, MTA-7H8, was generated, and then a competitive immunoassay for MTA determination was developed using europium cryptate-labeled MTA-7H8 and XL665-labeled MTA. In our homogeneous immunoassay, the percentage molar cross-reactivity of dcSAM with MTA-7H8 was 0.01% and the detection limit of MTA was 2.6 pmol/well. Our HTRF assay uses only one assay plate in which both enzyme reaction and MTA determination can be done successively. Therefore, our method can enable automatic screening of SPDS inhibitors from large numbers of samples.     

广州市珍稀濒危植物资源状况及保护策略

目前调查到广州市有20种国家重点保护植物和5种广东省重点保护植物。在野外调查的基础上,根据植物居群的大小和数量以及受威胁等级,建议将广州市分布的14种野生植物列为市级重点保护对象。通过分析植物的生存现状和受威胁因素等,对广州市野生珍稀濒危植物的保护提出了相应对策。     

Forest-cutting rapidly improves the demographic status of Paeonia officinalis, a species threatened by forest closure

In the Mediterranean region, the spread and densification of woodlands and shrublands subsequent to rural depopulation is a critical issue for the conservation of open-habitat plant species. Our objective was to assess the effectiveness of forest management to reduce the negative impact of forest closure on the persistence of a protected herbaceous perennial species Paeonia officinalis. Using demographic surveys from 2003 to 2008 in a woodland, open and managed habitat clear-cutted for the aim of our study, we assessed the effect of forest opening on plant performance and population dynamics. In addition, we performed a shading experiment on reproductive plants to mimic canopy closure and study its impact on plant growth and fecundity. Based on quadrat surveys and matrix models, we showed that forest cutting induced a rapid increase in plant performance and population asymptotic growth rate. Indeed, within 2 years, plant size, flower, seed and ovule numbers as well as the plant stage distribution, asymptotic growth rates and elasticity patterns shifted from values similar to those in the woodland habitat to values similar to those in the open habitat. Similarly, artificially shaded reproductive plants regressed within 2 years towards the vegetative stage. For perennial plants which have a stage in their life-cycle which allows for individual survival under unfavourable conditions such as the vegetative stage for P. officinalis, such demographic plasticity may be fundamental for their long-term persistence in temporally heterogeneous environments. Our study highlights the need to mix an experimental approach with a mid-term demographic survey in order to design efficient conservation management strategies for declining populations of rare species.     

5f-Element complexes with a p-tert-butylcalix[4]arene bearing phosphinoyl pendant arms: Separation from rare earths and structural studies

Phosphinoylated calixarenes feature high coordination ability toward f elements and a great potentiality toward actinide/rare earth separation. Here, we report three characteristic properties of a tetra-phosphinoylated p-tert-butylcalix[4]arene, B₄bL⁴ functionalized with phosphinoyl pendant arms: (i) its coordination ability toward Th(IV) complexation in organic medium, (ii) its ability to separate thorium from yttrium, lanthanum, and europium in three different organic media, and (iii) the X-ray crystal structure of the La complex. Thorium(IV) forms 1:1 and 1:2 (M:L) complexes with B₄bL⁴: Th(NO₃)₄(B₄bL⁴)_n·xH₂O (n = 1, x = 1, 1; n = 2, x = 4, 2). Spectroscopic data point to the inner coordination sphere of 1 and 2 containing nitrate ions and water molecules. Molecular modeling of 1 yielded an 8-coordinate species and its coordination polyhedron can be described as a distorted square antiprism while that for 2, a 9-coordinate species, as a distorted tricapped trigonal prism. The extraction study of tetravalent thorium and trivalent rare-earth (Y, La, Eu) ions from acidic nitrate media by B₄bL⁴ in chloroform shows thorium being much more extracted than the rare earths, with selectivity close to 100%. The extraction behavior can be easily modulated by changing the initial conditions (pH, nitrate concentration). The X-ray structure of [LaB₄bL⁴(H₂O)₅] CH₃CN·(ClO₄)₃ points to the La^III ion lying on a C₄ axis and being 9-coordinated by the four O(P) atoms and five O atoms from water molecules. It is located in the middle of the void formed by the four O-CH₂-PO(Me)₂ pendant arms.