Plant functional traits differ in adaptability and are predicted to be differentially affected by climate change

1. Climate change is testing the resilience of forests worldwide pushing physiological tolerance to climatic extremes. Plant functional traits have been shown to be adapted to climate and have evolved patterns of trait correlations (similar patterns of distribution) and coordinations (mechanistic trade‐off). We predicted that traits would differentiate between populations associated with climatic gradients, suggestive of adaptive variation, and correlated traits would adapt to future climate scenarios in similar ways.
2. We measured genetically determined trait variation and described patterns of correlation for seven traits: photochemical reflectance index (PRI), normalized difference vegetation index (NDVI), leaf size (LS), specific leaf area (SLA), δ¹³C (integrated water‐use efficiency, WUE), nitrogen concentration (N_CONC), and wood density (WD). All measures were conducted in an experimental plantation on 960 trees sourced from 12 populations of a key forest canopy species in southwestern Australia.
3. Significant differences were found between populations for all traits. Narrow‐sense heritability was significant for five traits (0.15–0.21), indicating that natural selection can drive differentiation; however, SLA (0.08) and PRI (0.11) were not significantly heritable. Generalized additive models predicted trait values across the landscape for current and future climatic conditions (>90% variance). The percent change differed markedly among traits between current and future predictions (differing as little as 1.5% (δ¹³C) or as much as 30% (PRI)). Some trait correlations were predicted to break down in the future (SLA:N_CONC, δ¹³C:PRI, and N_CONC:WD).
4. Synthesis: Our results suggest that traits have contrasting genotypic patterns and will be subjected to different climate selection pressures, which may lower the working optimum for functional traits. Further, traits are independently associated with different climate factors, indicating that some trait correlations may be disrupted in the future. Genetic constraints and trait correlations may limit the ability for functional traits to adapt to climate change.

     

Structure of vaccinia virus thymidine kinase in complex with dTTP: insights for drug design

Background  

Development of countermeasures to bioterrorist threats such as those posed by the smallpox virus (variola), include vaccination and drug development. Selective activation of nucleoside analogues by virus-encoded thymidine (dThd) kinases (TK) represents one of the most successful strategies for antiviral chemotherapy as demonstrated for anti-herpes drugs. Vaccinia virus TK is a close orthologue of variola TK but also shares a relatively high sequence identity to human type 2 TK (hTK), thus achieving drug selectivity relative to the host enzyme is challenging.     

The majority of G0 transgenic mice are derived from mosaic embryos

Most transgenic mice are generated by the direct microinjection of DNA fragments into the pronuclei of fertilized eggs. It has been generally assumed that the majority of integration events occur prior to the first round of chromosomal DNA replication (Palmiter and Brinster, 1986). In this study we have determined by comparison of PCR, Southern blot and transmission frequencies that at least 62% of integration events generate a mosaic (somatic and/or germline) G₀ transgenic mouse. Furthermore, the statistical probability of transgene-containing cells segregating to the various early embryo lineages implies that this is probably an underestimate of the true mosaic frequency. Thus, the majority of DNA injected into fertilized mouse eggs integrates after the first round of chromosomal DNA replication, therefore most G₀ transgenic mice are derived from a mosaic embryo.     

The dynamic instability of microtubules is not modulated by alpha-tubulin tyrosinylation.

The tyrosinylation of chick brain alpha-tubulin and the effects of the tyrosinylation status on the assembly and dynamic instability of chick brain MAP2:tubulin microtubule protein have been examined. Each of the eight major alpha-isotypes can be tyrosinylated in vitro, irrespective of whether a C-terminal tyrosine is genetically encoded. The extent of tyrosinylation is however limited to congruent to 0.3 mol.mol-1. The tyrosinylation status (0 vs. 0.3 mol.mol-1) has no effect on either the assembly kinetics of chick brain microtubule protein or on the rate of length redistribution following assembly and shearing. It is therefore unlikely that the tyrosinylation status directly affects the intrinsic stability of assembled microtubules since the rate of length redistribution is both a sensitive assay and a function of the kinetic parameters governing dynamic instability.     

Capuchin (Cebus apella) Tool Use in a Captive Naturalistic Environment

Captive tufted capuchins are proficient at both tool use and manufacture. However, their capacity to comprehend cause-effect relationships as they relate to tool use is a subject of debate. An ability to conceptualize task requirements in assessing the appropriateness of potential tools would be essential to efficient tool use in the wild. Observations of tool use among free-ranging populations of Cebus are extremely limited, and the importance of this behavior to capuchin feeding ecology is unclear. I tested tufted capuchins' ability to conceive solutions to a probing task in a naturalistic captive setting. Three out of 5 participants demonstrated an ability to consistently make and use tools selected from a wide variety of natural materials within a forest exhibit. Over 98% (N = 140) of the tools that they modified enabled them to successfully acquire food rewards. It is likely that wild Cebus apella shares this ability, and that tool use occurs under a highly specific set of natural conditions.