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Results for “functional traits”

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PubMed2004

Coordinated changes in photosynthesis, water relations and leaf nutritional traits of canopy trees along a precipitation gradient in lowland tropical forest.

We investigated leaf physiological traits of dominant canopy trees in four lowland Panamanian forests with contrasting mean annual precipitation (1,800, 2,300, 3,100 and 3,500 mm). There was near complete turn-over of dominant canopy tree species among sites, resulting in greater dominance of evergreen species with long-lived leaves as precipitation increased. Mean structural and physiological traits changed along this gradient as predicted by cost-benefit theories of leaf life span. Nitrogen content per unit mass (Nmass) and light- and CO2-saturated photosynthetic rates per unit mass (Pmass) of upper canopy leaves decreased with annual precipitation, and these changes were partially explained by increasing leaf thickness and decreasing specific leaf area (SLA). Comparison of 1,800 mm and 3,100 mm sites, where canopy access was available through the use of construction cranes, revealed an association among extended leaf longevity, greater structural defense, higher midday leaf water potential, and lower Pmass, Nmass, and SLA at wetter sites. Shorter leaf life spans and more enriched foliar delta15N values in drier sites suggest greater resorption and re-metabolism of leaf N in drier forest. Greater dominance of short-lived leaves with relatively high Pmass in drier sites reflects a strategy to maximize photosynthesis when water is available and to minimize water loss and respiration costs during rainless periods. Overall, our study links coordinated change in leaf functional traits that affect productivity and nutrient cycling to seasonality in lowland tropical forests.

Analysis of Variance↗

PubMed1999

Anatomical and functional reconstruction of the nigrostriatal system in vitro: selective innervation of the striatum by dopaminergic neurons.

To study development of the nigrostriatal pathway in an in vitro model system, organotypic slices obtained from rat pups (P4) and containing the striatum and the cortex were grown together with apposed embryonic (E13.5) mesencephalic blocks according to the static slice culture method of Stoppini et al. (1991; J. Neurosci. Methods 37:173-182). Under these conditions, mesencephalic dopaminergic (DA) fibers rapidly grow through the slice, preferentially its striatal portion. This innervation provides a true synaptic innervation to the striatum, as shown by the presence of DA terminals on striatal neurons. DA fibers are able to exert a functional influence, as seen by their ability to modulate c-Fos expression in striatal neurons in the same way as in vivo. Thus, blockade, under basal conditions, of the effect of spontaneously released dopamine by the D2 receptor antagonist haloperidol leads to the activation of c-Fos expression in the striatum. Furthermore, stimulation of DA release by amphetamine induces striatal c-Fos expression in a D1 receptor-dependent manner. Next, the mechanisms of the selective striatal innervation were examined. Indeed, DA fibers innervated specifically the striatum, avoiding the cortical portion of the slice. This selectivity seems to be specific for DA neurons; no selectivity could be observed when noradrenergic neurons were substituted for DA neurons. Short-term cocultures in a collagen gel of mesencephalic blocks with striatal blocks failed to reveal any oriented outgrowth of DA fibers from the mesencephalon, suggesting that the selective innervation observed in the organotypic slices results from some contact-dependent, presumably adhesive interactions rather than from the presence of some diffusible substance orienting the growth of DA fibers towards the striatum. On the other hand, DA neurons seeded onto striatal slices did not attach selectively onto the striatal portion of the slice, indicating that the putative specific adhesive interactions governing the selective striatal innervation are not the same as those determining the adhesion of the DA neurons. These results show that cocultures of cortex-striatum and mesencephalic slices result in a system that displays a number of the morphological and functional traits of the normal nigrostriatal system and that can be relied on as a good in vitro model of in vivo development.

Animals↗

PubMed2025

Escape from TGF-β-induced senescence promotes aggressive hallmarks in epithelial hepatocellular carcinoma cells.

Transforming growth factor-β (TGF-β) signaling and cellular senescence are key hallmarks of hepatocellular carcinoma (HCC) pathogenesis. Despite provoking senescence-associated growth arrest in epithelial HCC cells, elevated TGF-β activity paradoxically correlates with increased aggressiveness and poor prognosis in advanced tumors. Whether the transition between these dichotomous functions involves modulation of the senescence phenotype during disease progression remains elusive. Exploiting the epithelial HCC cell line Huh7 as a robust model, we demonstrate that chronic exposure to TGF-β prompts escape from Smad3-mediated senescence, leading to the development of TGF-β resistance. This altered state is characterized by an optimal proliferation rate and the acquisition of molecular and functional traits of less-differentiated mesenchymal cells, coinciding with differential growth capacity in 2D and 3D culture conditions, epithelial-to-mesenchymal transition (EMT), and increased invasiveness in vitro, and metastasis in vivo. Mechanistically, resistant cells exhibit defective activation and nuclear trafficking of Smad molecules, particularly Smad3, as ectopic activation of the TGF-β/Smad3 axis is able to reinstate TGF-β sensitivity. An integrated transcriptomic landscape reveals both shared and distinct gene signatures associated with senescent and TGF-β resistant states. Importantly, genetic ablation and molecular studies identify microtubule affinity regulating kinase 1 (MARK1) and glutamate metabotropic receptor 8 (GRM8) as critical modulators of the resistance phenomenon, potentially by impairing spatiotemporal signaling dynamics of Smad activity. Our findings unveil a novel phenomenon wherein epithelial HCC cells may exploit senescence plasticity as a mechanism to oppose TGF-β anti-tumor responses and progress towards more aggressive HCC phenotypes.

Humans↗

PubMed1984

The dynamics of quantifiable homeostasis. III: a linear model of certain metrical diseases.

A generalization of the linear, lagged, homeostatic process shows that whether a displacement of the trait function dies out with time, continues indefinitely, or shows a steadily amplifying (wild) oscillation depends on the value assumed by the product of the lag time and the restoration constant. Moreover, it is shown that if a steady displacing force is used rather than an instantaneous displacement, a new homing value results which is given by the ratio of the displacing force to the restoration coefficient. Combining these two developments furnishes grounds for determining whether or not an overshoot will occur when administration of a drug is stopped (for instance, the rebound thrombosis on discontinuing heparin). Further developments of these ideas show how the diabetes that begins in mature patients can be wholly accounted for by the well-known prolongation of the lag in insulin response that occurs in that disorder. If wild oscillation is to be avoided as the lag time increases, the restoration constant must be weakened (evidently by a systematic reduction in insulin receptors) and this weakening means that the homing value is displaced. Thus the hyperglycemia in this diabetes is to be seen as the price paid for avoiding wild oscillation. Provided that the therapeutic use of exogenous insulin is systematic and regular, rather than cybernetic, its success where endogenous (cybernetic) insulin secretion has failed is readily understood. The point is illustrated by a familiar analogy of a car driver with slow responses. The genetic and evolutionary implications of these ideas are outlined.

Cybernetics↗

PubMed2002

Information content of female copulation calls in yellow baboons.

In a wide variety of animal species, females produce vocalizations just before, during, or immediately after copulation. Observational and experimental evidence indicates that these copulation calls are sexually selected traits, functioning to promote competition between males for access to the calling female. In this paper, we present an acoustic analysis of variation in the form of copulation calls of female yellow baboons, Papio cynocephalus cynocephalus. In particular, we examine whether information about three factors-the calling female's reproductive state, the occurrence or absence of ejaculation, and the dominance rank of the mating male-is encoded in call structure and hence is potentially available to male receivers attending to the signal. Although several features of copulation calls were correlated with each of these factors, when all three were included in multiple regressions only reproductive state and rank of the mating male had independent effects on call form. These findings indicate that female copulation calls in this species signal information about the proximity to ovulation of the calling female and also the relative competitive strength of her mating partner.

Animals↗

PubMed1999

Biological functions of carotenoids--diversity and evolution.

Carotenoids first emerged in archaebacteria as lipids reinforcing cell membranes. To serve this function their long molecules have extremely rigid backbone due to the linear chain of usually 10 to 11 conjugated C=C bonds in transconfiguration--the length corresponding the thickness of hydrophobic zone of membrane which they penetrate as "molecular rivets". Carotenoids retain their membrane-reinforcing function in some fungi and animals. The general structure of carotenoid molecule, originally having evolved for mechanical functions in membranes, possess a number of other properties that were later used for independent functions. The most striking fact is that these properties proved to fit some new functions to perfection. The polyene chain of 9-11 double bonds absorbs light precisely in the gap of chlorophyll absorption--function as accessory light-harvesting pigments in all plants; Unique arrangement of electronic levels owing to the by polyene chain structure makes carotenoids the only natural compounds capable of excitation energy transfer both (i) from carotenoid excited state to chlorophyll in the light-harvesting complex and (ii) from triplet chlorophyll or singlet oxygen to carotenoid in photosynthetic reaction centers--protection of RC from photodamage. The linear system of conjugated C=C bonds provides high reducing potential of carotenoid molecules making them potent antioxidants in lipid formations. Still, there is a lack of evidence of the chemical antioxidant function of carotenoids, especially in higher organisms; most data demonstrate an antioxidant ability rather than a function. Carotenoids have many other independent biological functions, including: specific coloration patterns in plants and animals, screening from excessive light and spectral filtering, defense of egg proteins from proteases in some invertebrates; the direct carotenoid derivative--retinal--acts as visual pigment in all animals and as chromophore in bacteriorhodopsin photosynthesis, retinoic acid in animals and abscisic acid in plants serve as hormones. All these functions utilize various properties (mechanical, electronic, stereospecific) of a single structure evolved in bacteria for a single membrane-reinforcing function, thus demonstrating an example of pure evolutionary preadaptation. One of the practical conclusions that can be reached by reviewing uniquely diverse properties and functions of carotenoids is that, when considering possible mechanisms of their effects in organisms (e.g., anticarcinogenic action), all their functional traits should be taken into account.

Animals↗

PubMed2001

Identification of an initiator-like element within the HTLV-I promoter.

Using the 5' long terminal repeat (LTR) as its only promoter, the HTLV-1 provirus generates a single RNA transcript that undergoes differential splicing to express the various viral proteins. Examination of sequence near the transcription start site revealed an element resembling a transcriptional initiator (Inr) at position -8 to -15 in addition to the canonical TATA box at -25. To elucidate basal control of HTLV-I gene expression, functional traits of this element were examined. It specifically bound a protein complex, the mobility of which was altered by antibody to serum response factor, and independently mediated reporter gene expression. Mutating the Inr in a minimal construct reduced basal transcription, whereas mutation of the element within the context of the complete LTR left basal transcription unaffected. Presence of the element influenced transcription start site choices. Exhibiting many characteristics of an Inr, this element may play an important role in regulating HTLV-I gene expression in vivo, particularly during the long clinical latency period prior to development of HTLV-I-induced disease.

Base Sequence↗

PubMed1980

Identity of molecules bearing murine Ia alloantigenic specificities Ia.7 and Ia.22: evidence for a single type of I-E molecule in homozygotes.

In homozygous mice bearing I regions derived from haplotype k, only a single type of Ia molecule bearing the alloantigenic specificities Ia.7 and Ia.22 was found using techniques of sequential immune precipitation and tryptic peptide analysis. As suggested at the fourth Ir Gene Workshop (Sachs 1978), Ia.7 is considered here to be an antigenic determinant associated with I-E-subregion-encoded molecules, i.e., it is excluded from the I-C subregion. The I-C subregion is currently defined mainly by functional traits. It is now known that the I-E molecules are composed of an alpha chain encoded in the I-E subregion, and a beta chain encoded in the I-A subregion. Since the I-C subregion is not involved with the determination of these Ia molecules, and since in homozygotes there is apparently only a single type of molecule bearing both specificities Ia.7 and Ia.22, the term "I-E/C" molecule should probably be dropped in favor of the simpler designation I-E.

Animals↗

PubMed2006

A novel strategy for defining haplotypes by selective depletion using restriction enzymes.

Various single nucleotide polymorphisms (SNPs) have been investigated regarding association with gene expression levels or human diseases. Although different SNPs within one gene are frequently analyzed individually, it is highly probable that in the majority of the cases, a precise combination of SNP alleles, i.e., haplotype, determines a functional trait. Methods commonly used for haplotype determination, involving studies in families, cloning, or somatic cell hybrids, are expensive and time-consuming. We herein suggest a novel and simple strategy for haplotype determination, involving selective haplotype depletion with a restriction enzyme, followed by sequencing. We studied 11 LTA gene polymorphisms in 102 Brazilian individuals, and we applied this novel methodology for haplotyping 67 out of 70 LTA heterozygous individuals. We concluded that the method is rapid and efficient, and, as it includes only simple and widespread-used techniques, it could be used in most of the laboratories without further investment in equipments. The wider usage of haplotyping could be important to clarify contradictory results frequently observed among studies that focus on a single SNP.

Alleles↗

PubMed2006

Novel frequenin-modulated Ca2+-signaling membrane guanylate cyclase (ROS-GC) transduction pathway in bovine hippocampus.

Frequenin is a member of the neuronal Ca(2+) sensor protein family, implicated in being the modulator of the neurotransmitter release, potassium channels, phosphatidylinositol signaling pathway and the Ca(2+)-dependent exocytosis of dense-core granules in the PC12 cells. Frequenin exhibits these biological activities through its Ca(2+) myristoyl switch, yet the switch is functionally inactive. These structural and functional traits of frequenin have been derived through the use of recombinant frequenin. In the present study, frequenin (BovFrq) native to the bovine hippocampus has been purified, sequenced for its 9 internal fragments, cloned, and studied. The findings show that structure of the BovFrq is identical to its form present in chicken, rat, mouse and human, indicating its evolutionary conservation. Its Ca(2+) myristoyl switch is active in the hippocampus. And, BovFrq physically interacts and turns on yet undisclosed ONE-GC-like ROS-GC membrane guanylate cyclase transduction machinery in the hippocampal neurons. This makes BovFrq a new Ca(2+)-sensor modulator of a novel ROS-GC transduction machinery. The study demonstrates the presence and mechanistic features of this cyclic GMP signaling pathway in the hippocampal neurons, and also provides one more support for the evolving concept where the Ca(2+)-modulated membrane guanylate cyclase transduction machinery in its variant forms is a central operational component of all neurons.

Amino Acid Sequence↗

PubMed2006

Effects of snacks on energy intake: an evolutionary perspective.

The question addressed in this paper is whether the consumption of snacks contributes to higher energy intake and body weight in humans. Currently available snacks have a higher energy density than most of the foods that were available in Paleolithic diets. Humans have a weak defense against overeating, which is a functional trait from an evolutionary perspective. Various studies found that people do not compensate their energy intake after the consumption of snacks. This is particularly true for energy-containing drinks, which provide calories in liquid form. It is concluded that snack consumption may contribute to a positive energy balance.

Appetite↗

PubMed2006

Prefrontal dysfunction in schizophrenia controlling for COMT Val158Met genotype and working memory performance.

Earlier studies with functional imaging in schizophrenia have demonstrated dysfunction of the dorsolateral prefrontal cortex during working memory. Controlling for behavioral performance and for catechol-O-methyltransferase (COMT) Val158Met genotype, we here demonstrate in a functional magnetic resonance imaging paradigm that patients recruit greater neuronal resources in prefrontal cortex during working memory, suggesting that this phenotype is a core functional trait of the disease. We also replicated earlier findings that the Val allele of the COMT polymorphism is associated with greater engagement of the prefrontal cortex.

Adult↗

PubMed2006

Effect of different number of frozen spermatozoa inseminated on the reproductive performance of rabbit does.

The relationship between the number of frozen spermatozoa inseminated and fertility rate and litter size at birth in rabbit does was investigated. Six hundred artificial inseminations (AI) were performed on multiparous lactating does with three spermatozoa concentrations: 10, 25, 50x10(6)spermatozoa/AI. All the does were synchronized with 20 UI of eCG 2 days before AI. The estimated sexual receptivity was 87%. The freezing-thawing procedure strongly reduced kinetic and functional traits (acrosome integrity, capacitation) of the spermatozoa. The number of spermatozoa inseminated did not affect the reproductive performance: the mean fertility rate and litter size values were 51.5% and 7.6%, respectively. Sexually receptive does (n=522) inseminated with frozen spermatozoa showed a 58.0% fertility rate whereas, non-receptive does (n=78), had a very poor fertility rate (7.8%).

Acrosome↗

PubMed2005

Genetical genomics in humans and model organisms.

Genetical genomics has been proposed to map loci controlling gene-expression differences (eQTLs) that might underlie functional trait variation. We briefly review the studies in model species and conclude that, although they successfully demonstrate the utility of genetical genomics, they are too limited to unlock the full potential of this approach and some results should be interpreted with caution. We subsequently elaborate on two recent studies that use this approach in humans. The many differences between these studies complicate meaningful comparisons between them. A joint analysis of the two experiments offers some scope for more powerful genetical genomics.

Animals↗

PubMed2003

Functional fingerprints of folds: evidence for correlated structure-function evolution.

Using structural similarity clustering of protein domains: protein domain universe graph (PDUG), and a hierarchical functional annotation: gene ontology (GO) as two evolutionary lenses, we find that each structural cluster (domain fold) exhibits a distribution of functions that is unique to it. These functional distributions are functional fingerprints that are specific to characteristic structural clusters and vary from cluster to cluster. Furthermore, as structural similarity threshold for domain clustering in the PDUG is relaxed we observe an influx of earlier-diverged domains into clusters. These domains join clusters without destroying the functional fingerprint. These results can be understood in light of a divergent evolution scenario that posits correlated divergence of structural and functional traits in protein domains from one or few progenitors.

Adenosine Triphosphate↗

PubMed2002

Molecular and functional profiling of memory CD8 T cell differentiation.

How and when memory T cells form during an immune response are long-standing questions. To better understand memory CD8 T cell development, a time course of gene expression and functional changes in antigen-specific T cells during viral infection was evaluated. The expression of many genes continued to change after viral clearance in accordance with changes in CD8 T cell functional properties. Even though memory cell precursors were present at the peak of the immune response, these cells did not display hallmark functional traits of memory T cells. However, these cells gradually acquired the memory cell qualities of self-renewal and rapid recall to antigen suggesting the model that antigen-specific CD8 T cells progressively differentiate into memory cells following viral infection.

Animals↗

PubMed2001

Behavioural differences between three breed groups of hunting dogs confronted with domestic sheep.

When running free in open fields, domestic dogs occasionally display predatory behaviour towards domestic sheep. This has not yet been studied scientifically. The aim of the present study was to investigate the inclination to chase sheep in three breed groups of hunting dogs that are most frequently used in areas with grazing sheep. We studied 41 elkhounds, 29 hare hunting dogs and 68 English setters. Behaviours indicative of motivation for chasing or attacking sheep were examined in three different ways. A path test examined functional traits such as hunting ability, contact willingness, reactivity to sudden noise, and response towards a lone sheep. In a sheep confrontation test, loose-leashed dogs were observed in a fenced enclosure with sheep and given electric shocks through an electronic dog collar if within 1-2m from the sheep. A questionnaire to the dog owners supplied information on their dog's previous experience with sheep and behavioural responses to various types of novel stimuli. No significant sex differences were found. The elkhounds showed the highest interest in a lone sheep in the path test, and displayed the highest initial hunting motivation, the highest percentage of dogs starting a sheep attack, the highest attack severity, and were most frequently given el. shocks. The hare hunting dogs were intermediate, while setters showed the lowest values for these variables. Dogs reported as showing low fearfulness more frequently acted as potential sheep chasers in the tests. Dogs up to 3 years of age showed a more pronounced initial hunting motivation and more frequent attacks than older dogs, although there were no age differences in the number of el. shocks given in the test. The latter may be related to the more frequent abruption of attacks among younger dogs. The main factors predicting a high hunting motivation and attack severity were lack of previous opportunity to chase sheep, low fearfulness towards gunshots and unfamiliar people, and general interest in sheep shown when encountering them. Probability of sheep chasing differed between dog breeds and age groups. Previous experience and certain character traits were indicative of a high predatory motivation towards sheep.

Journal Article↗

PubMedDate not supplied

Spatial memory and hippocampal pallium through vertebrate evolution: insights from reptiles and teleost fish.

The forebrain of vertebrates shows great morphological variation and specialized adaptations. However, an increasing amount of neuroanatomical and functional data reveal that the evolution of the vertebrate forebrain could have been more conservative than previously realized. For example, the pallial region of the teleost telencephalon contains subdivisions presumably homologous with various pallial areas in amniotes, including possibly a homologue of the medial pallium or hippocampus. In mammals and birds, the hippocampus is critical for encoding complex spatial information to form map-like cognitive representations of the environment. Here, we present data showing that the pallial areas of reptiles and fish, previously proposed as homologous to the hippocampus of mammals and birds on an anatomical basis, are similarly involved in spatial memory and navigation by map-like or relational representations of the allocentric space. These data suggest that early in vertebrate evolution, the medial pallium of an ancestral fish group that gave rise to the extant vertebrates became specialized for processing and encoding complex spatial information, and that this functional trait has been retained through the evolution of each independent vertebrate lineage.

Animals↗