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Results for “Evolutionary adaptability”

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PubMed1996

The fine structure of large dense-core organelles in human locus coeruleus neurons.

Protein bodies, the characteristic spherical organelles present in human monoamine neurons, have been shown in previous electron microscope studies to originate as dense bodies in mitochondria. This study was designed to investigate the presence of catecholamine reaction products in the dense bodies of locus coeruleus neurons, in frozen fresh post-mortem brain tissue with the use of potassium permanganate (KMnO4) fixation. This fixation procedure forms a dense KMnO4/catecholamine reaction product, visible in the electron microscope, in the large dense-core vesicles of experimental animals. Our results demonstrate the localization of KMnO4 dense product in the cores of double membrane-bound spherical organelles, as well as in spherical structures in the matrix of typical mitochondria. No typical large dense-core vesicles were observed in these catecholamine neurons of the tissues studied. Our findings are consistent with the notion that altered mitochondria may contribute to the formation of a new type of large dense-core vesicle in the locus coeruleus neurons of man, which is probably an evolutionary adaptation of amine-storing organelles.

Adult↗

PubMedDate not supplied

Composition of fuel stores and digestive limitations to fuel deposition rate in the long-distance migratory thrush nightingale, Luscinia luscinia.

During their autumn migratory phase, thrush nightingales (Luscinia luscinia) previously starved for 2 d were allowed to refuel under three different ambient temperature conditions (-7 degrees, 7 degrees, and 22 degrees C). During the refueling period, as well as during the preceding control and starvation periods, food intake, body mass, and feces production were monitored. In addition, daily energy expenditure was measured during the refueling period. The compilation of the energy balance during the refueling period revealed an energy density of the deposited tissue of 33.6 kJ g-1. Assuming that the deposited tissue consists of fat and protein exclusively, with energy densities of 39.6 and 5.5 kJ g-1 wet mass, respectively, we estimated the deposited tissue to consist of 82% fat and 18% wet protein (6% dry protein and 12% water). Nitrogen balances during control, starvation, and refueling phases and during a period of prolonged and complete starvation indicated that 5% of the nutrient stores consisted of dry protein. Our results support recent findings that nutrient stores for migration often contain protein in addition to fat and consequently are 15%-25% less energy rich than pure fat stores. These proteins might be stored as muscle or other functional tissue and may be required to support the extra mass of the stores and/or reflect an incapacity of the metabolic machinery to catabolize far exclusively. Fuel deposition rate was positively related with ambient temperature, whereas food intake rate was unaffected by temperature. These results indicate that the rate of fuel deposition is limited by a ceiling in food intake rate; when this ceiling is reached, fuel deposition rate is negatively affected by daily energy expenditure rate. To a certain extent, the ceiling in food intake rate varies depending on feeding conditions over the previous days. These variations in food intake capacity probably reflect the building and breakdown of gut tissues and/or gut enzyme systems and might be insensible and not evolutionary adaptive. Significant energetic costs, however, are probably associated with the maintenance of gut tissues. It is therefore feasible that changes in digestive capacity are regulated and are directed at energy economization.

Analysis of Variance↗

PubMed2005

Evidence for multiple calcium response mechanisms in mammalian olfactory receptor neurons.

Olfactory receptor neurons employ a diversity of signaling mechanisms for transducing and encoding odorant information. The simultaneous activation of subsets of receptor neurons provides a complex pattern of activation in the olfactory bulb that allows for the rapid discrimination of odorant mixtures. While some transduction elements are conserved among many species, some species-specificity occurs in certain features that may relate to their particular physiology and ecological niche. However, studies of olfactory transduction have been limited to a relatively small number of vertebrate and invertebrate species. To better understand the diversity and evolution of olfactory transduction mechanisms, we studied stimulus-elicited calcium fluxes in olfactory neurons from a previously unstudied mammalian species, the domestic cat. Isolated cells from cat olfactory epithelium were stimulated with odorant mixtures and biochemical agents, and cell responses were measured with calcium imaging techniques. Odorants elicited either increases or decreases in intracellular calcium; odorant-induced calcium increases were mediated either by calcium fluxes through the cell membrane or by mobilization of intracellular stores. Individual cells could employ multiple signaling mechanisms to mediate responses to different odorants. The physiological features of these olfactory neurons suggest greater complexity than previously recognized in the role of peripheral neurons in encoding complex odor stimuli. The investigation of novel and unstudied species is important for understanding the mechanisms of odorant signaling that apply to the olfactory system in general and suggests both broadly conserved and species-specific evolutionary adaptations.

Animals↗

PubMed1997

Increases in rates of resistance to trimethoprim.

Trimethoprim alone or in combination with a sulfonamide is an effective and relatively inexpensive antibacterial medication. However, a dramatic increase in the rate of resistance to trimethoprim along with high-level resistance to sulfonamides has been seen during the past two decades. The mechanisms of resistance show a remarkable evolutionary adaptation.

Anti-Infective Agents, Urinary↗

PubMed2025

The genetic basis of chloride exclusion in grapevines.

Mediterranean regions are among the most important areas for global grape production, characterized by dry climates and frequent challenges associated with soil salinity. In these environments, chloride toxicity is a major factor limiting vine growth and fruit quality. Despite the critical role of chloride exclusion in salinity tolerance, the genetic mechanisms underlying this trait remain poorly understood. In this study, we analyzed natural variation in chloride exclusion using a diverse panel of 335 accessions representing 18 wild and cultivated Vitis species. This panel, comprising accessions from the southwestern United States and Mexico, captures a broad range of evolutionary adaptations to abiotic stress and provides a valuable genetic resource for breeding efforts aimed at introducing novel traits. Using genome-wide association and quantitative trait loci (QTL) mapping, we identified a major QTL on chromosome 8, now designated qClEx8.1, containing candidate genes encoding cation/H⁺ exchangers (CHXs), which are involved in ion transport and homeostasis. To validate these findings, we analyzed a mapping population derived from Vitis acerifolia longii 9018 and the commercial rootstock GRN3, confirming the chromosome 8 locus as a major determinant of chloride exclusion. Structural variant analysis revealed nonsynonymous substitutions within CHX genes that may influence protein function and salinity tolerance. Additionally, we discovered a novel QTL on chromosome 19 enriched with G-type lectin S-receptor-like serine/threonine-protein kinases, known regulators of stress signaling. By integrating phenotypic and genomic data across a diverse Vitis collection, this study advances our understanding of the genetic architecture underlying chloride exclusion and highlights candidate genes for breeding salt-tolerant rootstocks.

Vitis↗

PubMed2000

Expression of histo-blood group antigens by lipopolysaccharides of Helicobacter pylori strains from asian hosts: the propensity to express type 1 blood-group antigens.

Past studies have shown that the cell surface lipopolysaccharides (LPSs) of the ubiquitous human gastric pathogen Helicobacter pylori (a type 1 carcinogen) isolated from people residing in Europe and North America express predominantly type 2 Lewis x (Le(x)) and Le(y) epitopes and, infrequently, type 1 Le(a), Le(b), and Le(d) antigens. This production of Lewis blood-group structures by H. pylori LPSs, similar to those found in the surfaces of human gastric cells, allows the bacterium to mimic its human niche. In this study, LPSs of H.pylori strains extracted from patients living in China, Japan, and Singapore were chemically and serologically analyzed. When compared with Western H.pylori LPSs, these Asian strains showed a stronger tendency to produce type 1 blood groups. Of particular interest, and novel observations in H.pylori, the O-chain regions of strains F-58C and R-58A carried type 1 Le(a) without the presence of type 2 Le(x), strains R-7A and H607 were shown to have the capability of producing the type 1 blood group A antigen, and strains CA2, H507, and H428 expressed simultaneously the difucosyl isomeric antigens, type 1 Le(b) and type 2 Le(y). The apparent proclivity for the production of type 1 histo-blood group antigens in Asian H.pylori LPSs, as compared with Western strains, may be an adaptive evolutionary effect in that differences in the gastric cell surfaces of the respective hosts might be significantly dissimilar to select for the formation of different LPS structures on the resident H.pylori strain.

ABO Blood-Group System↗

PubMed2000

Sequence conservation and variability of imprinting in the Beckwith-Wiedemann syndrome gene cluster in human and mouse.

In human and mouse most imprinted genes are arranged in chromosomal clusters. This linked organization suggests coordinated mechanisms controlling imprinted expression. We have sequenced 250 kb in the centre of the mouse imprinting cluster on distal chromosome 7 and compared it with the orthologous Beckwith-Wiedemann gene cluster on human chromosome 11p15.5. This first comparative imprinting cluster analysis revealed a high structural and functional conservation of the six orthologous genes identified. However, several striking differences were also discovered. First, compared with the mouse the human sequence is approximately 40% longer, mostly due to insertions of two large repetitive clusters. One of these clusters encompasses an additional gene coding for a homologue of the ribosomal protein L26. Second, pronounced blocks of unique direct repeats characteristic of imprinted genes were only found in the human sequence. Third, two of the orthologous gene pairs Tssc4/TSSC4 and Ltrpc5/LTRPC5 showed apparent differences in imprinting between human and mouse, whereas others like Tssc6/TSSC6 were not imprinted in either organism. Together these results suggest a significant functional and structural variability in the centre of the imprinting cluster. Some genes escape imprinting in both organisms whereas others exhibit tissue- and species-specific imprinting. Hence the control of imprinting in the cluster appears to be a highly dynamic process under fast evolutionary adaptation. Intriguingly, whereas imprinted genes within the cluster contain CpG islands the non-imprinted Ltrpc5 and Tssc6/TSSC6 do not. This and additional comparisons with other imprinted and non-imprinted regions suggest that CpG islands are key features of imprinted domains.

Amino Acid Sequence↗

PubMed2005

Deletions on mouse Yq lead to upregulation of multiple X- and Y-linked transcripts in spermatids.

Deletions on the mouse Y-chromosome long arm (MSYq) lead to teratozoospermia and in severe cases to infertility. We find that the downstream transcriptional changes in the testis resulting from the loss of MSYq-encoded transcripts involve upregulation of multiple X- and Y-linked spermatid-expressed genes, but not related autosomal genes. Therefore, this indicates that in normal males, there is a specific repression of X and Y (gonosomal) transcription in post-meiotic cells, which depends on MSYq-encoded transcripts. Together with the known sex ratio skew in favour of females in the offspring of fertile MSYqdel males, this strongly suggests the existence of an intragenomic conflict between X- and Y-linked genes. Two potential antagonists in this conflict are the X-linked multicopy gene Xmr and its multicopy MSYq-linked relative Sly, which are upregulated and downregulated, respectively, in the testes of MSYqdel males. Xmr is also expressed during meiotic sex chromosome inactivation (MSCI), indicating a link between the MSCI and the MSYq-dependent gonosomal repression in spermatids. We therefore propose that this repression and MSCI itself are evolutionary adaptations to maintain a normal sex ratio in the face of X/Y antagonism.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Breast cancer and the brain: a neurodevelopmental hypothesis to explain the opposing effects of caloric deprivation during the Dutch famine of 1944-1945 on breast cancer and its risk factors.

Most studies on calorie deprivation and cancer risk in rodents show reductions in tumor occurrence. However, the few human studies on calorie restriction are conflicting. An overview is given of results in the DOM (diagnostic onderzoek mammacarcinoom) cohorts among women exposed to the Dutch Famine of 1944-1945. Opposing effects were found on risk factors (shortening of leg length, later menarche, and earlier menopause), whereas urinary estrogens and plasma insulin-like growth factor (IGF)-1 and IGF binding protein-3 were increased, as was breast cancer itself. Exposure between 2 and 10 y old was an unexpected window of susceptibility to the effects of calorie deprivation. The effects of famine exposure were most clearly seen in women who never gave birth. These opposing observations can be explained by a neurodevelopmental hypothesis on set-point shifts at the level of the diencephalons/hypothalamus, either directly or from rebound effects. Such a mechanism reflects old evolutionary adaptation systems in lower and higher organisms to cope with periods of stress and famine by adjusting, for example, reproductive functions. These effects in exposed women may later also affect their unexposed offspring. This hypothesis provides several testable, hormone-mediated corollaries on the relationships between the role of calories in a Westernized lifestyle and human cancer risk. The underlying developmental perspective, as opposed to a risk factor approach, can explain why certain ages, even before breast development, are especially sensitive to effects of large fluctuations in calories. The observations presented may have implications for preventive strategies such as promoting moderation of calorie intake to curb cancer risks.

Adult↗

PubMed2025

Evolutionary and Functional Analysis of Caspase-8 and ASC Interactions to Drive Lytic Cell Death, PANoptosis.

Caspases are evolutionarily conserved proteins essential for driving cell death in development and host defense. Caspase-8, a key member of the caspase family, is implicated in nonlytic apoptosis, as well as lytic forms of cell death. Recently, caspase-8 has been identified as an integral component of PANoptosomes, multiprotein complexes formed in response to innate immune sensor activation. Several innate immune sensors can nucleate caspase-8-containing PANoptosome complexes to drive inflammatory lytic cell death, PANoptosis. However, how the evolutionarily conserved and diverse functions of caspase-8 drive PANoptosis remains unclear. To address this, we performed evolutionary, sequence, structural, and functional analyses to decode caspase-8's complex-forming abilities and its interaction with the PANoptosome adaptor ASC. Our study distinguished distinct subgroups within the death domain superfamily based on their evolutionary and functional relationships, identified homotypic traits among subfamily members, and captured key events in caspase evolution. We also identified critical residues defining the heterotypic interaction between caspase-8's death effector domain and ASC's pyrin domain, validated through cross-species analyses, dynamic simulations, and in vitro experiments. Overall, our study elucidated recent evolutionary adaptations of caspase-8 that allowed it to interact with ASC, improving our understanding of critical molecular associations in PANoptosome complex formation and the underlying PANoptotic responses in host defense and inflammation. These findings have implications for understanding mammalian immune responses and developing new therapeutic strategies for inflammatory diseases.

Caspase 8↗

PubMed1994

Molecular cloning of a human small intestinal apolipoprotein B mRNA editing protein.

Mammalian small intestinal apolipoprotein B (apo B) mRNA undergoes posttranscriptional cytidine deamination with the production of an in frame stop codon and the translation of apo B48. We have isolated a cDNA from human jejunum which mediates in vitro editing of a synthetic apo B RNA template upon complementation with chicken intestinal S100 extracts. The cDNA specifies a 236 residue protein which is 69% identical to the apo B mRNA editing protein (REPR) cloned from rat small intestine [Teng, B., Burant, C. F. and Davidson, N. O. (1993) Science 260, 1816-1819] and which, by analogy, is referred to as HEPR. HEPR does not contain the carboxyl-terminus leucine zipper motif identified in REPR but contains consensus phosphorylation sites as well as the conserved histidine and both cysteine residues identified as a Zn2+ binding motif in other cytidine deaminases. The distribution of HEPR mRNA was predominantly confined to the adult small intestine with lower levels detectable by reverse-transcription polymerase chain reaction amplification in the stomach, colon and testis. These differences in the structure and distribution of the human as compared to the rat apo B mRNA editing protein suggest an important evolutionary adaptation in the mechanisms restricting apo B48 production to the small intestine.

APOBEC-1 Deaminase↗

PubMed1998

Long-range translational coupling in single-stranded RNA bacteriophages: an evolutionary analysis.

In coliphage MS2 RNA a long-distance interaction (LDI) between an internal segment of the upstream coat gene and the start region of the replicase gene prevents initiation of replicase synthesis in the absence of coat gene translation. Elongating ribosomes break up the repressor LDI and thus activate the hidden initiation site. Expression studies on partial MS2 cDNA clones identified base pairing between 1427-1433 and 1738-1744, the so-called Min Jou (MJ) interaction, as the molecular basis for the long-range coupling mechanism. Here, we examine the biological significance of this interaction for the control of replicase gene translation. The LDI was disrupted by mutations in the 3'-side and the evolutionary adaptation was monitored upon phage passaging. Two categories of pseudorevertants emerged. The first type had restored the MJ interaction but not necessarily the native sequence. The pseudorevertants of the second type acquired a compensatory substitution some 80 nt downstream of the MJ interaction that stabilizes an adjacent LDI. In one examined case we confirmed that the second site mutations had restored coat-replicase translational coupling. Our results show the importance of translational control for fitness of the phage. They also reveal that the structure that buries the replicase start extends to structure elements bordering the MJ interaction.

Base Sequence↗

PubMed2004

Plasmodium interspersed repeats: the major multigene superfamily of malaria parasites.

Functionally related homologues of known genes can be difficult to identify in divergent species. In this paper, we show how multi-character analysis can be used to elucidate the relationships among divergent members of gene superfamilies. We used probabilistic modelling in conjunction with protein structural predictions and gene-structure analyses on a whole-genome scale to find gene homologies that are missed by conventional similarity-search strategies and identified a variant gene superfamily in six species of malaria (Plasmodium interspersed repeats, pir). The superfamily includes rif in P.falciparum, vir in P.vivax, a novel family kir in P.knowlesi and the cir/bir/yir family in three rodent malarias. Our data indicate that this is the major multi-gene family in malaria parasites. Protein localization of products from pir members to the infected erythrocyte membrane in the rodent malaria parasite P.chabaudi, demonstrates phenotypic similarity to the products of pir in other malaria species. The results give critical insight into the evolutionary adaptation of malaria parasites to their host and provide important data for comparative immunology between malaria parasites obtained from laboratory models and their human counterparts.

Amino Acid Motifs↗

PubMed2006

SECIS elements in the coding regions of selenoprotein transcripts are functional in higher eukaryotes.

Expression of selenocysteine (Sec)-containing proteins requires the presence of a cis-acting mRNA structure, called selenocysteine insertion sequence (SECIS) element. In bacteria, this structure is located in the coding region immediately downstream of the Sec-encoding UGA codon, whereas in eukaryotes a completely different SECIS element has evolved in the 3'-untranslated region. Here, we report that SECIS elements in the coding regions of selenoprotein mRNAs support Sec insertion in higher eukaryotes. Comprehensive computational analysis of all available viral genomes revealed a SECIS element within the ORF of a naturally occurring selenoprotein homolog of glutathione peroxidase 4 in fowlpox virus. The fowlpox SECIS element supported Sec insertion when expressed in mammalian cells as part of the coding region of viral or mammalian selenoproteins. In addition, readthrough at UGA was observed when the viral SECIS element was located upstream of the Sec codon. We also demonstrate successful de novo design of a functional SECIS element in the coding region of a mammalian selenoprotein. Our data provide evidence that the location of the SECIS element in the untranslated region is not a functional necessity but rather is an evolutionary adaptation to enable a more efficient synthesis of selenoproteins.

Amino Acid Sequence↗

PubMed2002

Immune system evolution among anthropoid primates: parasites, injuries and predators.

In this study we investigate whether present-day variation in a key component of the immune system (baseline leucocyte concentrations) represents evolutionary adaptation to ecological factors. In particular, we test three hypotheses, namely that leucocyte concentrations will be positively related to one of the following: risk of disease transmission between hosts, which is related to host abundance (hypothesis 1), risk of disease infection from the environment due to parasite viability and abundance (hypothesis 2), and risk of injury and subsequent infection, for example following attacks by predators (hypothesis 3). No support was found for hypothesis 1: neither population density nor group size were associated with variation in leucocyte concentrations. Hypothesis 2 was supported: for both sexes, lymphocyte and phagocyte concentrations were positively correlated with annual rainfall, as predicted if interspecific variation in the immune system is related to parasite prevalence (primates suffer higher rates of parasitism in wetter habitats). Support was also provided for hypothesis 3: for both males and females, platelet concentrations were negatively related to body mass, as predicted if injury risk affects immune system evolution, because animals with larger body mass have a relatively lower surface area available to injury. Additional support was provided for hypothesis 3 by the finding that for males, the sex which plays the active role in troop defence and retaliation against predators, concentration of platelets was positively correlated with rate of predation. In conclusion, our analysis suggests that the risk of disease infection from the environment and the risk of injury have played a key role in immune system evolution among anthropoid primates.

Animals↗

PubMed2003

Causal belief and the origins of technology.

The primary function of the brain is to control movement. Human interactions with the environment, unlike those of other primates, are based on a belief in cause and effect, and this led to technology. Experiments requiring simple manipulations of the environment show that chimpanzees do not have concepts of causes or forces. Children, by contrast, have causal beliefs as a developmental primitive, and these can be demonstrated even in infants. It is proposed that the evolution of causal thinking was essential for the development of tool use, as it is not possible to make a complex tool without understanding cause and effect. This was a great evolutionary adaptive advantage. The evolution of language may have been linked to the same process. It has been technology that resulted from causal beliefs, not social interaction, that has driven human evolution.

Adaptation, Physiological↗

PubMed1997

Signal transduction in the carnivorous plant Sarracenia purpurea. Regulation of secretory hydrolase expression during development and in response to resources.

Carnivory in plants has developed as an evolutionary adaptation to nutrient-poor environments. A significant investment of the resources of a carnivorous plant is committed to producing the traps, attractants, and digestive enzymes needed for the carnivory. The cost:benefit ratio of carnivory can be improved by either maximizing the prey capture rate or by reducing the metabolic commitment toward carnivory. Using the pitcher plant Sarracenia purpurea, we have investigated whether the expression of the hydrolytic enzymes needed for digestion is regulated in response to the presence of prey. Expression of protease, RNase, nuclease, and phosphatase activities could be induced in the fluid of nonactive traps by the addition of nucleic acids, protein, or reduced nitrogen, suggesting that hydrolase expression is induced upon perception of the appropriate chemical signal. Hydrolase expression was also developmentally controlled since expression commenced upon opening of a trap, increased for several days, and in the absence of prey largely ceased within 2 weeks. Nevertheless, the traps remained competent to induce expression in response to the appropriate signals. These data suggest that in young traps hydrolase expression is developmentally regulated, which is later replaced by a signal transduction mechanism, and they demonstrate the ability of a carnivorous species to respond to the availability of resources.

Adaptation, Physiological↗

PubMed2006

Overexpression of INFLORESCENCE DEFICIENT IN ABSCISSION activates cell separation in vestigial abscission zones in Arabidopsis.

Plants may shed organs when they have been injured or served their purpose. The differential pattern of organ abscission in different species is most likely the result of evolutionary adaptation to a variety of life styles and environments. The final step of abscission-related cell separation in floral organs of wild-type Arabidopsis thaliana, which only abscises sepals, petals, and stamens, is controlled by INFLORESCENCE DEFICIENT IN ABSCISSION (IDA). Here, we demonstrate that Arabidopsis 35S:IDA lines constitutively overexpressing IDA exhibit earlier abscission of floral organs, showing that the abscission zones are responsive to IDA soon after the opening of the flowers. In addition, ectopic abscission was observed at the bases of the pedicel, branches of the inflorescence, and cauline leaves. The silique valves also dehisced prematurely. Scanning electron microscopy indicated a spread of middle lamella degradation from preformed abscission zone cells to neighboring cells. A transcript encoding an arabinogalactan protein (AGP) was upregulated in the 35S:IDA lines, and large amounts of AGP were secreted at the sites of abscission. AGP was shown to be a constituent of wild-type floral abscission zones during and soon after cell separation had been completed. We suggest that the restricted expression pattern of IDA precludes abscission of nonfloral organs in Arabidopsis.

Arabidopsis↗