Selection on plasticity of seasonal life-history traits using random regression mixed model analysis

Theory considers the covariation of seasonal life-history traits as an optimal reaction norm, implying that deviating from this reaction norm reduces fitness. However, the estimation of reaction-norm properties (i.e., elevation, linear slope, and higher order slope terms) and the selection on these is statistically challenging. We here advocate the use of random regression mixed models to estimate reaction-norm properties and the use of bivariate random regression to estimate selection on these properties within a single model. We illustrate the approach by random regression mixed models on 1115 observations of clutch sizes and laying dates of 361 female Ural owl Strix uralensis collected over 31 years to show that (1) there is variation across individuals in the slope of their clutch size-laying date relationship, and that (2) there is selection on the slope of the reaction norm between these two traits. Hence, natural selection potentially drives the negative covariance in clutch size and laying date in this species. The random-regression approach is hampered by inability to estimate nonlinear selection, but avoids a number of disadvantages (stats-on-stats, connecting reaction-norm properties to fitness). The approach is of value in describing and studying selection on behavioral reaction norms (behavioral syndromes) or life-history reaction norms. The approach can also be extended to consider the genetic underpinning of reaction-norm properties.     

Plant- and stimulus-specific variations in remote-controlled sieve-tube occlusion

Phloem injury triggers local sieve-plate occlusion including callose-mediated constriction and protein plugging of sieve pores. In intact plants, reversible sieve-plate occlusion is induced by electric potential waves (EPWs)—accompanied by Ca²⁺-influx—as result of distant burning. Here, we present additional results which pertain to (a) the variability of EPW-profiles in relation to forisome conformation in intact Vicia faba plants and (b) the differential occlusion reactions to burning and cutting in various plant species. A correlation between stimulus perception and mode of phloem loading is discussed.Key words: callose, electrical potential waves, forisome, membrane potential, phloem transport, sieve-element occlusion, wound potentials     

Influence of Ileo-Caecal Cannulation and Oxytetracycline on Ileo-Caecal and Rectal Coliform Populations in Pigs

The effect of surgery (insertion of an ileo-caecal cannula) and a subsequent parenteral treatment with oxytetracycline on the ileo-caecal and rectal coliform populations in 7 Swedish Yorkshire castrates were studied. Samples were collected during surgery as well as 3, 7, 14 and 20 days post surgery. The diversity of the enteric coliform flora was initially high both in the ileo-caecal ostium and in rectum. No alteration in the diversity of the enteric coliform flora was observed following surgery and treatment with oxytetracycline. As the insertion of ileo-caecal cannulas did not affect the intestinal coliform flora this study gives support to the use of this technique to mirror processes in the small intestine of pigs. Further, the diversity of the enteric coliform flora was unaffected by the parenteral treatment with oxytetracycline.     

Lack of effector cell function and altered tetramer binding of tumor-infiltrating lymphocytes

Tumor-specific CD8 T cell responses to MCA102 fibrosarcoma cells expressing the cytotoxic T cell epitope gp33 from lymphocytic choriomeningitis virus were studied. MCA102(gp33) tumors grew progressively in C57BL/6 mice, despite induction of peripheral gp33-tetramer(+) T cells that were capable of mediating antiviral protection, specific cell rejection, and concomitant tumor immunity. MCA102(gp33) tumors were infiltrated with a high number ( approximately 20%) of CD11b(+)CD11c(-) macrophage-phenotype cells that were able to cross-present the gp33 epitope to T cells. Tumor-infiltrating CD8 T cells exhibited a highly activated phenotype but lacked effector cell function. Strikingly, a significant portion of tumor-infiltrating lymphocytes expressed TCRs specific for gp33 but bound MHC tetramers only after cell purification and a 24-h resting period in vitro. The phenomenon of "tetramer-negative T cells" was not restricted to tumor-infiltrating lymphocytes from MCA102(gp33) tumors, but was also observed when Ag-specific T cells derived from an environment with high Ag load were analyzed ex vivo. Thus, using a novel tumor model, allowing us to trace tumor-specific T cells at the single cell level in vivo, we demonstrate that the tumor microenvironment is able to alter the functional activity of T cells infiltrating the tumor mass.     

Structural maintenance of chromosomes (SMC) proteins, a family of conserved ATPases

The structural maintenance of chromosomes (SMC) proteins are essential for successful chromosome transmission during replication and segregation of the genome in all organisms. SMCs are generally present as single proteins in bacteria, and as at least six distinct proteins in eukaryotes. The proteins range in size from approximately 110 to 170 kDa, and each has five distinct domains: amino- and carboxy-terminal globular domains, which contain sequences characteristic of ATPases, two coiled-coil regions separating the terminal domains and a central flexible hinge. SMC proteins function together with other proteins in a range of chromosomal transactions, including chromosome condensation, sister-chromatid cohesion, recombination, DNA repair and epigenetic silencing of gene expression. Recent studies are beginning to decipher molecular details of how these processes are carried out.     

Nestling immune response to phytohaemagglutinin is not heritable in collared flycatchers

The response to intradermally injected phytohaemagglutinin (PHA-response) is a commonly used quantification of avian immunocompetence (the ability to resist pathogens). Parasite-mediated sexual selection requires heritable immunocompetence, but evidence for heritability of PHA-response in birds largely stems from full-sib comparisons. Using an animal model approach, we quantified the narrow-sense heritability of PHA-response in 1626 collared flycatcher (Ficedula albicollis) nestlings from 332 families, most of which were cross-fostered. Nestling PHA-response was not significantly heritable (h2=0.06+/-0.10), but was subject to non-heritable nest-of-origin effects (10% of variation). Our findings illustrate that full-sib comparisons of immunological measures may lead to an inflated estimate of heritability and also reveal a limited role of nestling PHA-response for sexual selection in this population.     

A strong genetic correlation underlying a behavioural syndrome disappears during development because of genotype–age interactions

In animal populations, as in humans, behavioural differences between individuals that are consistent over time and across contexts are considered to reflect personality, and suites of correlated behaviours expressed by individuals are known as behavioural syndromes. Lifelong stability of behavioural syndromes is often assumed, either implicitly or explicitly. Here, we use a quantitative genetic approach to study the developmental stability of a behavioural syndrome in a wild population of blue tits. We find that a behavioural syndrome formed by a strong genetic correlation of two personality traits in nestlings disappears in adults, and we demonstrate that genotype–age interaction is the likely mechanism underlying this change during development. A behavioural syndrome may hence change during organismal development, even when personality traits seem to be strongly physiologically or functionally linked in one age group. We outline how such developmental plasticity has important ramifications for understanding the mechanistic basis as well as the evolutionary consequences of behavioural syndromes.     

Hormonally regulated programmed cell death in barley aleurone cells

Cell death was studied in barley (cv Himalaya) aleurone cells treated with abscisic acid and gibberellin. Aleurone protoplasts incubated in abscisic acid remained viable in culture for at least 3 weeks, but exposure to gibberellin initiated a series of events that resulted in death. Between 4 and 8 days after incubation in gibberellin, >70% of all protoplasts died. Death, which occurred after cells became highly vacuolated, was manifest by an abrupt loss of plasma membrane integrity followed by rapid shrinkage of the cell corpse. Hydrolysis of DNA began before death and occurred as protoplasts ceased production of alpha-amylase. DNA degradation did not result in the accumulation of discrete low molecular weight fragments. DNA degradation and cell death were prevented by LY83583, an inhibitor of gibberellin signaling in barley aleurone. We conclude that cell death in aleurone cells is hormonally regulated and is the final step of a developmental program that promotes successful seedling establishment.     

Concentrations and ecological risks of metals in surface sediments of some coastal creeks in the Niger Delta,Nigeria

The concentrations of nine metals were measured by atomic absorption spectrophotometry in surface sediments of three coastal creeks, namely, the Ifie, Egbokodo and Ubeji creeks, in the Niger Delta of Nigeria, from August 2012 to January 2013. The aim of the study was to provide information on the spatial and seasonal distribution patterns, degree of contamination, and ecological risks of metals in these sediments. The mean concentrations of the nine metals in these creek sediments ranged from 0.30 to 3.20?mg kg^?1 Cd; 10.7 to 24.7?mg kg^?1 Pb, 125 to 466?mg kg^?1 Cr; 3.1.10 to 14.9?mg kg^?1 Cu; 4.7 to 14.3?mg kg^?1 Co; 61.1 to 115?mg kg^?1 Ni; 106 to 183?mg kg^?1 Mn; 52.0 to 170?mg kg^?1 Zn and 5 469 to 20 639?mg kg^?1 Fe. In general, the metal concentrations were higher in the dry season than the wet season, except for Cr. The concentrations of Cd, Cr, Ni and Zn were above their regulatory control limits in sediment as specified by the Nigerian Regulatory Authority and Cd was identified as the main ecological risk factor. The enrichment factors for the studied metals followed the order: Cd > Cr > Ni > Zn > Pb > Co > Mn > Cu. The average multiple pollution index values indicated that these sediments were severely polluted with significant inputs from Cd, Ni and Cr.