Testing the stability of transfer functions

In dendroclimatology, testing the stability of transfer functions using cross-calibration verification (CCV) statistics is a common procedure. However, the frequently used statistics reduction of error (RE) and coefficient of efficiency (CE) merely assess the skill of reconstruction for the validation period, which does not necessarily reflect possibly instable regression parameters. Furthermore, the frequently used rigorous threshold of zero which sharply distinguishes between valid and invalid transfer functions is prone to an underestimation of instability. To overcome these drawbacks, we here introduce a new approach – the Bootstrapped Transfer Function Stability test (BTFS). BTFS relies on bootstrapped estimates of the change of model parameters (intercept, slope, and r²) between calibration and verification period as well as the bootstrapped significance of corresponding models. A comparison of BTFS, CCV and a bootstrapped CCV approach (BCCV) applied to 42,000 pseudo-proxy datasets with known properties revealed that BTFS responded more sensitively to instability compared to CCV and BCCV. BTFS performance was significantly affected by sample size (length of calibration period) and noise (explained variance between predictor and predictand). Nevertheless, BTFS performed superior with respect to the detection of instable transfer functions in comparison to CCV.     

The conservation value of unlogged and logged forests for native mammals on the East Coast of Peninsular Malaysia

Tropical forests across the world provide important habitats for a diverse number of conservation priority species, yet are under threat from a range of anthropogenic impacts including logging. This study aims to quantify mammalian biodiversity in unlogged and logged forests in the adjoining Tembat and Petuang Forest Reserves, Terengganu, on the East Coast of Peninsular Malaysia. Data was collected over a series of surveys using direct and indirect observation methods from 2008 to 2014. A total of 30 medium and large sized mammals species were identified, with 27 of those species found in unlogged forests and 22 species in logged forests. Carnivores encompassed 11 species from 67 observations representing 15% of the total number of observations. The family Felidae had the highest number of species (six species), followed by Hylobatidae, Cercopithecidae and Suidae with three species each. A total of 17 species contributed to more than 90% of the mammal community in the unlogged and logged forests, while six species were uncommon and only observed once during the entire survey. Species abundance in the unlogged forest was significantly greater than the logged forests, but the difference was not significant for species richness. This study provides critical baseline information on the impact of unlogged and logged forests and the identification of threatened species warrant the establishment of conservation measures such as anti-poaching patrol and ranger stations in the study area.     

Translocation - A key factor limiting the efficiency of nitrogen fixation in legume nodules

A hypothesis is presented that the availability of water for export of nitrogenous products from legume nodules is a major factor limiting the efficiency of symbiotic nitrogen fixation. Water for export of solutes in the xylem probably depends largely on the import of water and reduced carbon in the phloeum, and one function of respiration may be to dispose of reduced carbon in order to increase the supply of water. A second hypothesis presented is that control of gas diffusion in soybean nodules is largely restricted to the cortex nearby the vascular bundles, thus making possible the linkage of solute balances in xylem and phloem with resistance to diffusion. These concepts are used in a re-examination of literature on manipulations of nodules and nodulated plants such as lowering of light levels, water stress, defoliation, stem girdling, and alteration of oxygen supply. The concept of translocation as a major factor limiting efficiency of symbiotic fixation is consistent with the failure of superior rhizobial isolates to improve N input significantly, and this limitation could also prevent exploitation of superior bacterial symbionts in the future     

Evolutionary change in seed size among some legume species: The effects of phylogeny

The importance of phylogenetic effects in controlling seed size variation at the macroevolutionary levels was examined using species of a well-defined, monophyletic family, the Leguminosae. A nested ANOVA was used to separate variance components at the various taxonomic levels such as subfamily, genus, and subgenus. Statistical significance was found at most of the taxonomic levels examined, which suggests that phylogeny as shown by the accepted taxonomy of the family, exerted a substantial influence over seed size variation. Thus, there appears to be a characteristic mean seed size for each genus and subgenus. The overall positive correlation between plant height and seed size was interpreted as a scaling of seed size to plant height. When the effect of plant height was controlled, the amount of variance changed to some extent across taxonomic levels, though resulting in no change in statistical significance at various taxonomic levels. This results indicate that phylogenetic effects in seed size variation among congeneric or consubgeneric groupings were largely independent of allometric effects. The patterns of variance components and intraclass correlation coefficients for seed size differed to some extent among subfamilies. The difference in those patterns among taxa will reflect evolutionary change more closely with larger sample sizes. A simple inverse relationship between seed size and number per fruit among related legume species was difficult to generalize. This was perhaps due to phylogenetic constraints on seed size and/or seed number (or ovule number). These results demonstrate that phylogeny and plant height affect seed size variation among related species.     

Morpho-colorimetric characterization by image analysis to identify diaspores of wild plant species

Digital images of ex situ germplasm stored in the Sardinian Germplasm Bank (BG-SAR) were used for the application of image analysis techniques at the Stazione Sperimentale di Granicoltura per la Sicilia. The analysed accessions refer to 148 taxonomic units belonging to 102 genera and 47 families, typical of the Sardinian flora, and of the Mediterranean basin in general.The images of diaspores were acquired by a flatbed scanner and elaborated with a macro specially developed for the morphometric and colorimetric measurements. This method allowed carrying out a database for the characterization of autochthonous germplasm in entry to the bank and the realization of statistic classifiers for the discrimination of genera and species within the following families: Apiaceae, Boraginaceae, Caryophyllaceae, Cistaceae, Fabaceae and Scrophulariaceae. Such classifiers, based on the linear discriminant analysis (LDA) technique and checked by cross-validation, showed a performance included between 74.3% and 96.4%.In addition, for the genus Astragalus, it was possible to elaborate a classifier able to identify very similar taxa of a species complex, obtaining a performance between 83.7% and 100%. Such analysis proved the validity of the methodology also from the taxonomic point of view.Suggestions for subsequent methodological progress, which could offer applications in other research issues, such as ecological analysis, soil seed bank and archaeological botany are proposed.     

A comparison of the wood anatomy of 11 species from two cerrado habitats (cerrado s.s. and adjacent gallery forest)

A comparative study of the secondary xylem (wood) anatomy of 11 species (38 specimens) occurring in cerrado s.s. and the adjacent gallery forest (both cerrado s.l. habitat) was made with the aim of identifying the anatomical characteristics of ecological value and correlating them with the environmental conditions. The anatomical features that vary, in general, between the two habitats are: growth ring distinctness (well or poorly defined); tyloses and deposits (more abundant in cerrado specimens); gelatinous fibres (more evident in cerrado specimens and in different patterns between habitats); variation in paratracheal and banded parenchyma (more abundant in cerrado); and more cells per parenchyma strand in cerrado. In general, gallery forest specimens have wider vessels, fewer vessels per square millimetre and larger intervessel pits, indicating more efficient water conduction, whereas cerrado s.s. specimens are the opposite, with low vulnerability and mesomorphy indices, demonstrating greater safety under conditions of water stress. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ?? , ??–??.     

Tobacco embryogenesis: Storage-protein-accumulating cells of embryo, suspensor, and endosperm are able to undergo cytokinesis

Summary It is widely accepted that seed storage proteins accumulate only in cells which have entered the cell expansion phase and do not continue to divide. Here we present data indicating that the accumulation of storage globulins in tobacco begins already during early embryogenesis in a period of sustained mitotic activity. Western blot analysis revealed that polypeptides of the legumin-like 12S globulins (M_r 60000, 40000, 20000) appear at mid/late globular stage, whereas the vicilin-like 7S globulin (M_r 50000) follows during the transition from heart to torpedo stage. The accumulation of legumin-like polypeptides begins first in the endosperm during the mid globular stage followed in the embryo-suspensor complex during the heart-shaped stage. The vicilin-related fraction appears first in the endosperm and three days later in the embryo. Examination of individual cells from squash preparations revealed that protein bodies are not confined to intermitotic cells, but are also present in cells undergoing mitosis. Protein bodies of dividing cells situated outside the mitotic apparatus are not metabolized during cytokinesis. The only cell type which loses its protein bodies completely prior to the first mitotic division is the primary hypophysis cell. Our finding that storage proteins can occur in dividing cells independent of their origin and developmental capacity indicates that the cell expansion hypothesis of storage protein accumulation has to be revised.     

Screening of rice cultivars for Cr-stress response by using the parameters of seed germination,morpho-physiological and antioxidant analysis

Rice is the most important crop for the majority of population across the world with sensitive behavior toward heavy metals such as chromium (Cr) in polluted regions. Although, there is no information on the Cr resistance phenotyping in rice. Herein, two different groups of rice cultivars (normal, and hybrid) were used, each group with 14 different rice cultivars. Firstly, seed germination analysis was conducted by evaluating various seed germination indices to identify the rice cultivars with greatest seed germination vigor. Furthermore, exposure of chromium (Cr) toxicity to 28 different rice varieties (NV1-NV14, HV1-HV14) caused noticeable plant biomass reduction. Subsequently, NV2, NV6, NV10, NV12, NV13 (normal type), HV1, HV4, HV8, and HV9 (hybrid types) were pragmatic as moderately sensitive varieties, while NV3, NV4, NV9, and NV14 (normal type), HV3, HV6, HV7, and HV13 were observed as moderately tolerant. Although, NV7, and HV10 were ranked most sensitive cultivars, and NV11, and HV14 were considered as most tolerant varieties as compared to the other rice (both groups) genotypes. Afterward, Cr induced reduction in chlorophyll pigments were significantly lesser in HV14 relative to NV11, NV7, and especially HV10, and as a result HV14 modulated the total soluble sugar level as well as reduced ROS accumulation, and MDA contents production by stimulating the antioxidant defense mechanism conspicuously which further reduced the electrolyte leakage as well. Our outcomes provide support to explore the Cr tolerance mechanism in cereal crops as well as knowledge about rice breeding with increased tolerance against Cr stress.     

Künstliche Luzerneheubereitungsverfahren in Ungarn

Abstract

An experiment was performed with Rumen Simulation Technique (Rusitec) in which the fermentation of mixed ration of hay (12.8 g/d) and wheat bran (3.2 g/d) was compared with the fermentation of the same diet supplemented with 2.5 and 10 mg monensin. The duration of the experiment was 12 days. During the first six days the fermentation conditions in Rusitec were stabilised. The end products of fermentation and indices of protein synthesis were determined. The energy efficiency of volatile fatty acids (VFA), proportion of fermented hexose energy on VFA energy and on energy of bacterial matter were increased in the presence of monensin. The proportion of fermented hexose energy in methane energy was decreased. Utilization of glucose and production of adenosintriphosphate were not affected. The balance of metabolic H₂ was reduced and this was manifested in decreasing production, utilization and recovery of metabolic H₂. Microbial efficiency expressed per mol ATP (g/mol) was increased by monensin from 7.8 to 12.6. The indices of protein synthesis — protein conversion ratio, degradability of protein and microbial protein synthesis efficiency were increased and non protein utilization ratio decreased in the presence of monensin.

Es wurde ein Versuch nach der Pansensimulationsmethode durchge-führt, in dem die Fermentierung einer gemischten Ration aus Heu (12,8 g/d) und Weizenkleie (3,2 g/d) mit der Fermentierung der gleichen Ration unter Zusatz von 2, 5 und 10 mg Monensin/d verglichen wurde. Die Dauer des Versuchs betrug 12 Tage, wovon die ersten sechs Tage der Stabilisierung der Fermentierungsbedingungen im Rusitec-System dienten.

Es wurden die Endprodukte der Fermentierung und die Kennziffern der Proteinsynthese bestimmt. Die Energieausbeute an Flüchtigen Fettsäuren (FFS), der Energieanteil fermentierter Hexose an der FFS-Energie und der Energie an Bakterienmasse erhöhten sich bei Zusatz von Monensin. Der Energieanteil fermentierter Hexose an der Methanenergie verringerte sich. Die Ausnutzung von Glukose und die Produktion von Adenosintriphosphat waren unbeeinflußt. Die Bilanz von metabolischem H₂ war verringert, was sich im Absinken der Production, der Nutzung und der Wiederauffindung von metabolischem H₂ zeigte. Die mikrobielle Wirksamkeit pro mol ATP (g/mol) erhöhte sich durch Monensin von 7,8 auf 12,6. Die Kennziffern der Proteinsynthese, die Proteinkonversionsrate, die Abbaubarkeit von Protein und die mikrobielle Proteinsynthesewirksamkeit erhöhten sich und die NPN-Nutzungsrate verringerte sich in Gegenwart von Monensin.