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Results for “Evolutionary adaptability”

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PubMed1984

Insulin and trauma: some thoughts.

Trauma and/or sepsis produce a net negative nitrogen balance due mainly to muscle protein breakdown. Lymphokines (interleukins) appear to be the hormonal signal which negates insulin's anabolic effect on muscle resulting in net catabolism. In contrast, their effects on immune and reparative cells appear additive to insulin's anabolic effect augmenting tissue repair and increasing immunologic defense, but at the expense of muscle nitrogen. This logical evolutionary adaptation did not anticipate that parenteral alimentation could provide both the needed glucose for tissue repair, thus obviating muscle protein catabolism to provide precursor amino acids for hepatic gluconeogenesis and the amino acids for tissue reconstruction.

Journal Article↗

PubMed1990

The geometry of evolution.

Some structures are more suitable for self-organization through the Darwin-Wallace mechanism of variation and selection than others. Such evolutionary adaptability (or evolvability) can itself evolve through variation and selection, either by virtue of being associated with reliability and stability or by hitchhiking along with the advantageous traits whose appearance it facilitates. In order for a structure to evolve there must be a reasonable probability that genetic variation carries it from one adaptive peak to another; at the same time the structure should not be overly unstable to phenotypic perturbations, as this is incompatible with occupying a peak. Organizations that are complex in terms of numbers of components and interactions are more likely to meet the peak-climbing condition, but less likely to meet the stability condition. Biological structures that are characterized by a high degree of component redundancy and multiple weak interactions satisfy these conflicting pressures.

Biological Evolution↗

PubMed1982

Partial purification and characterization of an alkaline phosphatase in Helix nemoralis and in Octopus vulgaris.

1. Alkaline phosphatase (AP) present in the liver of Helix nemoralis and of Octopus vulgaris; enzyme was purified by homogenization, ultracentrifugation, n-butanol treatment, acetone fractionation and Sephadex G-200 chromatography. 2. The two enzymes show a similar enzyme-substrate affinity, but differ in several properties (molecular weight, electrophoretic mobility, optimum pH, substrate inhibition); a possible correlation of them with different evolutionary adaptations is suggested. 3. Possible roles of AP in Mollusca are discussed.

Alkaline Phosphatase↗

PubMed1986

Comparative study of tyrosinases from different sources: relationship between halide inhibition and the enzyme active site.

The inhibition of tyrosinases from frog epidermis (Rana esculenta ridibunda), mushroom (Agaricus bisporus) and Harding-Passey mouse melanoma by halides is compared. In all cases, the inhibition is pH dependent, increasing when the pH decreases. The order of inhibition is I- greater than Br- greater than Cl- much greater than F- for frog epidermis tyrosinase, F- greater than I- greater than Cl- greater than Br- for mushroom tyrosinase and F- greater than Cl- much greater than Br- greater than I- for the mouse melanoma enzyme. These results are discussed in terms of the active site accessibility to exogenous ligands. The activation energies of the enzyme-catalysed L-dopa oxidation were also calculated, being the values 6.86, 17.01 and 20.25 kcal/mol for frog epidermis, mushroom and Harding-Passey mouse melanoma, respectively. A relationship between these values and the evolutionary adaptation of these enzymes is proposed.

Animals↗

PubMed2004

Oxidative stress in limpets exposed to different environmental conditions in the Beagle Channel.

The aim of this work was to study the oxidative profile of digestive glands of two limpets species (Nacella (Patinigera) magellanica and Nacella (Patinigera) deaurata) exposed to different environmental conditions. The intertidal population of N. (P.) magellanica is subjected to a wide variety of stresses not experienced by N. (P.) deaurata. Although a typical electron paramagnetic resonance (EPR) spectrum of ascorbyl radical in digestive gland from both limpets was observed, neither ascorbyl radical content nor the ascorbyl radical content/ascorbate content ratio was significantly different, suggesting that the difference in the environmental conditions did not appear to be responsible for developing alterations in the oxidative status of both organisms at the hydrophilic level (e.g. cytosol). Lipid peroxidation in the digestive glands was estimated, both as the content of thiobarbituric acid reactive substances (TBARS) and as the content of lipid radicals assessed by EPR, in both organisms. TBARS and lipid radical content were 34.8 and 36.5%, respectively, lower in N. (P.) magellanica as compared to N. (P.) deaurata. On the other hand, total iron content and the rate of generation of superoxide anion were 47.9 and 51.4%, respectively, lower in N. (P.) magellanica as compared to N. (P.) deaurata. The activity of catalase and superoxide dismutase (SOD) was 35.3 and 128.6% higher in N. (P.) magellanica as compared to N. (P.) deaurata, respectively. No significant differences were determined between the digestive glands of both molluscs regarding the content of total thiols. alpha-Tocopherol and beta-carotene content were significantly lower in N. (P.) magellanica as compared to N. (P.) deaurata. A distinctive EPR signal for the adduct Fe--MGD--NO (g = 2.03 and a(N) = 12.5 G) was detected in the homogenates of digestive glands of both limpets. A significant difference in the content of the Fe-MGD-NO adduct in digestive glands from N. (P.) magellanica and N. (P.) deaurata (491 +/- 137 and 839 +/- 63 pmol/g FW, respectively) was observed. Taken as a whole, the data presented here indicated that coping with environmental stressing conditions requires a complex adjustment of the physiological metabolic pathways to ensure survival by minimizing intracellular damage. It is likely that N. (P.) magellanica has a particular evolutionary adaptation to extreme environmental conditions by keeping iron content low and antioxidant activities high.

Analysis of Variance↗

PubMed2006

Scallop lens Omega-crystallin (ALDH1A9): a novel tetrameric aldehyde dehydrogenase.

Scallop eye lens Omega-crystallin is an inactive aldehyde dehydrogenase (ALDH1A9) related to cytoplasmic ALDH1A1 and mitochondrial ALDH2 that migrates by gel filtration chromatography as a homodimer. Because mammalian ALDH1A1 and ALDH2 are homotetramers, we investigated the native molecular mass of scallop Omega-crystallin by multi-angle laser light scattering. The results indicate that the scallop Omega-crystallin is a tetrameric, not a dimeric protein. Moreover, phylogenetic tree analysis shows that scallop Omega-crystallin clusters with the mitochondrial ALDH2 and ALDH1B1 rather than the cytoplasmic ALDH1A, yet it lacks the mitochondrial N-terminal leader sequence characteristic of the mitochondrial ALDHs. The mitochondrial grouping, enzymatic inactivity, and anomalous gel filtration behavior make scallop cytoplasmic Omega-crystallin an interesting protein for structural studies of evolutionary adaptations to become an enzyme-crystallin.

Amino Acid Sequence↗

PubMed2004

Carbonic anhydrase inhibitors. Inhibition of the newly isolated murine isozyme XIII with anions.

The inhibition of the newly discovered cytosolic carbonic anhydrase (CA, EC 4.2.1.1) isozyme XIII of murine origin (mCA XIII) has been investigated with a series of anions, such as the physiological ones (bicarbonate, chloride), or the metal complexing anions (cyanate, cyanide, azide, hydrogen sulfide, etc), nitrate, nitrite, sulfate, sulfamate, sulfamide as well as with phenylboronic and phenylarsonic acids. The best mCA XIII inhibitors were cyanate, thiocyanate, cyanide and sulfamide, with K(I)-s in the range of 0.25microM-0.74 mM, whereas fluoride, iodide, azide, carbonate and hydrogen sulfide were less effective (K(I)-s in the range of 3.0-5.5mM). The least effective inhibitors were sulfate, chloride and bicarbonate (K(I)-s in the range of 138-267 mM). The affinity of mCA XIII for anions is very different from that of the other cytosolic isozymes (hCA I and II) or the mitochondrial isozyme hCA V. This resistance to inhibition by the physiological anions bicarbonate and chloride suggests an evolutionary adaptation of CA XIII to the presence of high concentrations of such anions (e.g., in the reproductive tract of both female and male), and the possible participation of this isozyme (similarly to CA II, CA IV and CA V) in metabolons with proteins involved in the anion exchange and transport, such as the anion exchangers (AE1-3) or the sodium bicarbonate co-transporter (NBC1 and NBC3) proteins, which remain to be identified.

Animals↗

PubMed2004

Carbonic anhydrase inhibitors: inhibition of the membrane-bound human isozyme IV with anions.

The membrane-associated human isozyme of carbonic anhydrase, hCA IV, has been investigated for its interaction with anion inhibitors, for the CO(2) hydration reaction catalyzed by this enzyme. Surprisingly, halides were observed to act as potent hCA IV inhibitors, with inhibition constants in the range of 70-90 microM, although most of these ions, and especially fluoride, the best hCA IV inhibitor among the halides, are weak inhibitors of other isozymes, such as hCA I, II and V. The metal poisons cyanate, cyanide and hydrogen sulfide were weaker hCA IV inhibitors (K(i)'s in the range of 0.6-3.9 mM), whereas thiocyanate, azide, nitrate and nitrite showed even weaker inhibitory properties (K(i)'s in the range of 30.8-65.1 mM). Sulfate was a good hCA IV inhibitor (K(i) of 9 mM), although it is a much weaker inhibitor of isozymes I, II, V and IX. Excellent hCA IV inhibitory properties showed sulfamic acid, sulfamide, phenylboronic acid and phenylarsonic acid, with K(i)'s in the range of 0.87-0.93 microM, whereas their affinities for the other investigated isozymes were in the millimolar range. The interaction of some anions with the mitochondrial isozyme hCA V has also been investigated for the first time here. It has been observed that among all these isozymes, hCA V has the lowest affinity for bicarbonate and carbonate (K(i)'s in the range of 82-95 mM), which may represent an evolutionary adaptation of this isozyme to the rather alkaline environment (pH 8.5) within the mitochondria, where hCA V plays important functions in some biosynthetic reactions involving carboxylating enzymes (pyruvate carboxylase and acetyl coenzyme A carboxylase). There are important differences of affinity for anions between the two membrane-associated isozymes, hCA IV and hCA IX.

Anions↗

PubMed2004

Carbonic anhydrase inhibitors. Interaction of isozymes I, II, IV, V, and IX with phosphates, carbamoyl phosphate, and the phosphonate antiviral drug foscarnet.

A detailed inhibition study of five carbonic anhydrase (CA, EC 4.2.1.1) isozymes with inorganic phosphates, carbamoyl phosphate, the antiviral phosphonate foscarnet as well as formate is reported. The cytosolic isozyme hCA I was weakly inhibited by neutral phosphate, strongly inhibited by carbamoyl phosphate (K(I) of 9.4 microM), and activated by hydrogen- and dihydrogenphosphate, foscarnet and formate (best activator foscarnet, K(A)=12 microM). The cytosolic isozyme hCA II was weakly inhibited by all the investigated anions, with carbamoyl phosphate showing a K(I) of 0.31 mM. The membrane-associated isozyme hCA IV was the most sensitive to inhibition by phosphates/phosphonates, showing a K(I) of 84 nM for PO(4)(3-), of 9.8 microM for HPO(4)(2-), and of 9.9 microM for carbamoyl phosphate. Foscarnet was the best inhibitor of this isozyme (K(I) of 0.82 mM) highly abundant in the kidneys, which may explain some of the renal side effects of the drug. The mitochondrial isozyme hCA V was weakly inhibited by all phosphates/phosphonates, except carbamoyl phosphate, which showed a K(I) of 8.5 microM. Thus, CA V cannot be the isozyme involved in the carbamoyl phosphate synthetase I biosynthetic reaction, as hypothesized earlier. Furthermore, the relative resistance of CA V to inhibition by inorganic phosphates suggests an evolutionary adaptation of this mitochondrial isozyme to the presence of high concentrations of such anions in these energy-converting organelles, where high amounts of ATP are produced by ATP synthetase, from ADP and inorganic phosphates. The transmembrane, tumor-associated isozyme hCA IX was on the other hand slightly inhibited by all these anions.

Antiviral Agents↗

PubMed2005

Carbonic anhydrase inhibitors. Inhibition of isozymes I, II, IV, V, and IX with anions isosteric and isoelectronic with sulfate, nitrate, and carbonate.

The inhibition of five human carbonic anhydrase (hCA, EC 4.2.1.1) isozymes; the cytosolic hCA I and II, the membrane-bound hCA IV, the mitochondrial hCA V, and the tumor-associated, transmembrane hCA IX, with anions isosteric and isoelectronic with sulfate, nitrate, and carbonate; such as chlorate, perchlorate, bromate, iodate, periodate, silicate, bismuthate, vanadate, molybdate, and wolframate is reported. Apparently, the geometry of the inhibitor (tetrahedral or trigonal) does not influence its binding to the Zn(II) ion of the enzyme active site, but the nature of the central element is the most important factor influencing potency. Isozymes hCA I and II are best inhibited by chlorate, perchlorate, and silicate, together with the anions structurally related to sulfate, sulfamate, and sulfamidate, but sulfate itself is a weak inhibitor (inhibition constant of 74 mM against hCA I and 183 mM against hCA II). Molybdate is a very weak hCA I inhibitor (K(I) of 914 mM) but it interacts with hCA II (K(I) of 27.5mM). Isozyme IV is well inhibited by sulfate (K(I) of 9 mM), sulfamate, and sulfamidate (in the low micromolar range), but not by perchlorate (K(I) of 767 mM). The mitochondrial isozyme V has the lowest affinity for sulfate (K(I) of 680 mM) and carbonate (K(I) of 95 mM) among all the investigated isozymes, suggesting on one hand its possible participation in metabolon(s) with sulfate anion exchanger(s), and on the other hand an evolutionary adaptation to working at higher pH values (around 8.5 in mitochondria) where rather high amounts of carbonate in equilibrium with bicarbonate may be present. Metasilicate, isosteric to carbonate, is also about a 10 times weaker inhibitor of this isozyme as compared to other CAs investigated here (K(I) of 28.2 mM). Surprisingly, the tumor-associated isozyme IX is resistant to sulfate inhibition (K(I) of 154 mM) but has affinity in the low micromolar range for carbonate, sulfamate, and sulfamidate (K(I) in the range of 8.6-9.6 microM). This constitutes another proof that this isozyme best works at acidic pH values present in tumors, being inhibited substantially at higher pH values when more carbonate may be present. Bromate and chlorate are quite weak CA IX inhibitors (K(I) s of 147-274 mM).

Anions↗

PubMed2005

Carbonic anhydrase inhibitors. Interaction of isozymes I, II, IV, V, and IX with carboxylates.

A detailed inhibition study of five carbonic anhydrase (CA, EC 4.2.1.1) isozymes with carboxylates including aliphatic (formate, acetate), dicarboxylic (oxalate, malonate), hydroxy/keto acids (l-lactate, l-malate, pyruvate), tricarboxylic (citrate), or aromatic (benzoate, tetrafluorobenzoate) representatives, some of which are important intermediates in the Krebs cycle, is presented. The cytosolic isozyme hCA I was strongly activated by acetate, oxalate, pyruvate, l-lactate, and citrate (K(A) around 0.1 microM), whereas formate, malonate, malate, and benzoate were weaker activators (K(A) in the range 0.1-1mM). The cytosolic isozyme hCA II was weakly inhibited by all the investigated anions, with inhibition constants in the range of 0.03-24 mM. The membrane-associated isozyme hCA IV was the most sensitive to inhibition by carboxylates, showing a K(I) of 99 nM for citrate and oxalate, of 2.8 microM for malonate and of 14.5 microM for pyruvate among others. The mitochondrial isozyme hCA V was weakly inhibited by all these carboxylates (K(I)s in the range of 1.67-25.9 mM), with the best inhibitor being citrate (K(I) of 1.67 mM), whereas this is the most resistant CA isozyme to pyruvate inhibition (K(I) of 5.5mM), which may be another proof that CA V is the isozyme involved in the transfer of acetyl groups from the mitochondrion to the cytosol for the provision of substrate(s) for de novo lipogenesis. Furthermore, the relative resistance of CA V to inhibition by pyruvate may be an evolutionary adaptation of this mitochondrial isozyme to the presence of high concentrations of this anion within this organelle. The transmembrane, tumor-associated isozyme hCA IX was similar to isozyme II in its slight inhibition by all these anions (K(I) in the range of 1.12-7.42 mM), except acetate, lactate, and benzoate, which showed a K(I)>150 mM. The lactate insensitivity of CA IX also represents an interesting finding, since it is presumed that this isozyme evolved in such a way as to show a high catalytic activity in hypoxic tumors rich in lactate, and suggests a possible metabolon in which CA IX participates together with the monocarboxylate/H(+) co-transporter in dealing with the high amounts of lactate/H(+) present in tumors.

Antigens, Neoplasm↗

PubMed2004

The varying distribution of intra- and inter-vertebral height ratios determines the prevalence of vertebral fractures.

Credible inferences regarding the burden of vertebral fractures (VFs) cannot be made without a globally accepted quantitative definition of 'fracture'. Currently, differences in anterior, middle, or posterior vertebral heights (VHs) within a vertebra, or between adjacent vertebrae, are used to define 'fracture'. However, VH differences are essential for the construction of thoracolumbar curves, evolutionary adaptations that provide stability in bipedal stance and gait. As there is no reference standard to distinguish anatomical variation from fracture, approaches to defining a VF use a reference range of VH ratios derived in premenopausal women or derived by trimming, a method that iteratively removes the tails of a distribution of VH ratios to produce a normal distribution. From this, reference ranges of VH ratio means and standard deviations (SDs) are obtained and a nominal deviation of 15% or more, or 3 SD or more is regarded as a 'fracture'. We measured VHs by quantitative vertebral morphometry (QVM) and bone mineral density (BMD) by dual energy X-ray absorptiometry in 697 Lebanese women (age 20-89 years) to compare the prevalence of VF ascertained by published methods and a new method that uses the premenopausal range (without trimming) and requires two VH abnormalities. VF prevalence using published methods reached 60% to 70% in pre- and post-menopausal women, and in women with normal or high BMD because VH ratios were not normally distributed and cut-offs used to define VF fracture fell within the observed distribution of the data. The new method resulted in a VF prevalence of 3.3% in younger and 14% in older women, 7% (high), 10% (middle), and 20% (low) BMD tertiles consistent with the notion that the method detected VF due to bone fragility. We suggest that using a fixed trimming method to define reference range and cut-offs or applying fixed cut-offs to identify VFs in populations, where these ratios are not normally distributed, may result in the capture of anatomical variation, not structural failure. Thus, group differences in the VF prevalence may reflect differences in methodology, not bone fragility. Improved criteria to define VF are needed before credible inferences can be made regarding the burden of VFs in women and men, and between sexes, races, countries, decades, and placebo arms of clinical trials.

Absorptiometry, Photon↗

PubMed2006

Sleep quantitation in common marmoset, cotton top tamarin and squirrel monkey by non-invasive actigraphy.

Sleep quantitation data on the Neotropical primate species, apart from the squirrel monkey, are still sparse. As such, we have quantitated sleep in the common marmosets (Callithrix jacchus), cotton top tamarins (Saguinus oedipus) and squirrel monkeys (Saimiri sciureus) reared in one primate facility simultaneously, by non-invasive actigraphy. The range in total sleep time/24h measured for male adult common marmosets, cotton top tamarins and squirrel monkeys were 713-793 min (n=4), 707-889 min (n=4) and 459-475 min (n=2) respectively. The range in sleep episode length /12h dark phase for marmosets, tamarins and squirrel monkeys were 21-52 min (n=3), 10-28 min (n=4) and 9-15 min (n=2) respectively. Since vigilance is a critical evolutionary adaptive feature of predator avoidance among Callitrichid monkeys and squirrel monkeys, the shorter ranges in sleep episode length recorded, even under captivity, in this study could be interpreted as probable indicators of such vigilance behavior during the rest phase. We hypothesize that the vigilance behavior when it exists during a primate's active phase should also prevail when it is at rest (sleep). This hypothesis deserves additional testing in female Callitrichid monkeys.

Animals↗

PubMed2004

Locomotor performance and muscle metabolic capacities: impact of temperature and energetic status.

In aquatic ectotherms, muscle metabolic capacities are strongly influenced by exogenous factors, principally temperature and food availability. Seasonal changes in temperature lead many organisms to modify their metabolic machinery so as to maintain capacity even in "slower" cold habitats. Modifications of mitochondrial capacities are central in this response. The increases in protein-specific oxidative capacities of mitochondria during cold acclimation of temperate fishes do not occur during the evolutionary adaptation to cold in Antarctic species. Instead, Antarctic fishes tend to increase the proportion of fibre volume devoted to mitochondria, perhaps to facilitate intracellular distribution of oxygen and metabolites. Variation in energetic status can drastically modify muscle metabolic status, with glycolytic muscle changing more than oxidative muscle. This in turn impacts swimming performance. A decrease in the condition of cod leads endurance at speeds above Ucrit to drop by 70%. Sprint swimming is less affected, perhaps as it does not exhaust glycolytic muscle. We used interindividual variation in muscle metabolic capacities to identify correlates of swimming performance in stickleback and cod. Activities of cytochrome c oxidase in glycolytic muscle are a correlate of sprint swimming in stickleback (Gasterosteus aculeatus) and cod (Gadus morhua), whereas lactate dehydrogenase activities in glycolytic muscle are a correlate of cod endurance swimming. In scallops, gonadal maturation leads to virtually complete mobilisation of glycogen from muscle. This does not reduce the capacity of the scallops, Chlamys islandica and Euvola ziczac, to mount escape responses, but significantly slows their recuperation from exhaustive exercise. Muscle metabolic capacities fall in parallel with glycogen mobilisation. In the compromise between muscles' dual roles as a motor and a macromolecular reserve, a significant loss in locomotory ability occurs during gametogenesis and spawning. Reproductive fitness takes the upper hand over maintenance of performance.

Adaptation, Physiological↗

PubMed2005

Melatonin pathway: breaking the 'high-at-night' rule in trout retina.

Pineal melatonin synthesis increases at night in all vertebrates, due to an increase in the activity of arylalkylamine N-acetyltransferase (AANAT). Melatonin is also synthesized in the retina of some vertebrates and it is generally assumed that patterns of pineal and retinal AANAT activity and melatonin production are similar, i.e. they exhibit a high-at-night pattern. However, the situation in fish is atypical because in some cases retinal melatonin increases during the day, not the night. Consistent with this, we now report that light increases the activity and abundance of the AANAT expressed in trout retina, AANAT1, at a time when the activity and abundance of pineal AANAT, AANAT2, decreases. Likewise, exposure to darkness causes retinal AANAT protein and activity to decrease coincident with increases in the pineal gland. Rhythmic changes in retinal AANAT protein and activity are 180 degrees out of phase with those of retinal AANAT1 mRNA; all appear to be driven by environmental lighting, not by a circadian oscillator. The atypical high-during-the-day pattern of retinal AANAT1 activity may reflect an evolutionary adaptation that optimizes an autocrine/paracrine signaling role of melatonin in photoadaptation and phototransduction; alternatively, it might reflect an adaptation that broadens and enhances aromatic amine detoxification in the retina.

Acetylserotonin O-Methyltransferase↗

PubMed2004

Lifespan extension by dietary restriction in female Drosophila melanogaster is not caused by a reduction in vitellogenesis or ovarian activity.

Dietary restriction (DR) extends lifespan in a wide range of organisms. DR also reduces daily and lifetime fecundity. The latter may be an evolutionary adaptation to survive periods of food shortage. Reproductive rate is often negatively correlated with lifespan, and a reduced cost of reproduction could be the mechanism by which DR extends lifespan. We tested this hypothesis in Drosophila melanogaster females, by directly suppressing different aspects of reproduction and measuring the effect on the response of lifespan and age-specific mortality to DR. DR resulted in lifespan extension in females kept with males, in females kept without males, in females with vitellogenesis blocked by the mutant ovoD1 and in females with no germline as a result of X-irradiation. Moreover, rapid (48 h) changes in age-specific mortality, previously seen in fertile females switched between full feeding and DR, were also seen in ovoD1 females. Furthermore, these rapid changes in age-specific mortality in cohorts of fertile wild type females were not accompanied by concurrent changes in egg-production. These results indicate either that reduced reproduction is not necessary for lifespan extension by DR in Drosophila females, or that the relevant aspects of reproduction act upstream of our interventions and were therefore not blocked in our experiments.

Animals↗

PubMed2026

LitCTL1: A novel C-type lectin involved in the mucosal and cellular immunity of the common periwinkle Littorinalittorea.

C-type lectins (CTLs) are vital pattern-recognition receptors (PRRs) that mediate innate immune responses in mollusks, yet their characterization in Caenogastropoda, the largest gastropod group, remains limited. This study characterizes LitCTL1, a novel secreted single-domain C-type lectin from the common periwinkle, Littorina littorea. The 199-amino acid polypeptide contains a conserved carbohydrate recognition domain with canonical QPD and WND motifs and is predicted to form a homodimer. Uniquely, LitCTL1 was localized in both circulating hemocytes and mucus-secreting epithelial cells of the foot, mantle, and hypobranchial gland - the first report of such dual localization for a molluscan lectin, linking systemic and mucosal defense. Expression analysis revealed that LitCTL1 is constitutively expressed in hemocytes. Functional assays with recombinant LitCTL1 demonstrated its role as a potent opsonin with hemagglutinating activity, significantly enhancing hemocyte spreading and the phagocytosis of zymosan. Genomic analysis reveals that LitCTL1 belongs to a rapidly diversifying, genus-specific expansion distinct from conserved perlucin-like lineages. These results identify LitCTL1 as a key effector molecule in both systemic and mucosal innate immunity, likely reflecting an evolutionary adaptation to the microbial challenges of the intertidal environment.

Animals↗

PubMed2003

Identification and characterization of simple sequence repeats in the genomes of Shigella species.

A variety of simple sequence repeats (SSRs) have been identified in the genome of Shigella flexneri serotype 2a (strain Sf301), an enteric pathogen that causes bacillary dysentery in man. The distribution of SSRs, with unit length ranging from 1 to 9 nucleotides, was biased in different regions of the genome. The tri-, tetra- and hexanucleotide SSRs prevailed in the coding regions while the mono- and dinucleotide SSRs were more common in the noncoding regions. Many intergenic SSRs are less than 30 bp away from the downstream open reading frames (ORFs), suggesting a potential role in transcriptional regulation. To study polymorphism of SSRs, we compared 17 coding-region SSRs from strain Sf301 with the corresponding sequences from 23 other strains of four Shigella species. Five chromosomal loci were found to be polymorphic, of which those from S. flexneri strains were most variable. Particularly interesting is the C5-1 locus in the coding sequence of the hcaD gene encoding a subunit of ferredoxin reductase. Depending on the insertion of variable numbers of the unit sequence (CGCAG), the Shigella hcaD genes can encode truncated products due to premature stop codons or frame shifts, or products with extended core alpha helices that leads to radical alterations in the predicted tertiary structure. Hence, SSRs may serve as genotyping markers for epidemiological investigations, and may offer insights into evolutionary adaptation of the pathogens.

Amino Acid Sequence↗