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PubMed2006

[Prevalence and treatment of pharyngeal Chlamydia trachomatis infections].

In recent years, the number of the patients with pharyngeal infection caused by Chlamydia trachomatis is believed to be on the rise due to diversification in sexual behaviors. In addition, pharyngeal infection by C. trachomatis is often asymptomatic, and this is also believed to be a major factor for the increase of the disease. In this study, we conducted a survey among general females and commercial sex workers (CSWs) to study their sexual behavior and prevalence of chlamydial infections (in uterine cervix and pharynx). The results showed that orogenital contact has become a common act, even for general females. Chlamydial infections of uterine cervix were found in 33.3% and 7.9% of CSWs and general females, respectively. Chlamydial infections of pharynx were found in 22.5% and 5.2% of CSWs and general females, respectively. The evaluation of treatments of these infections with clarithromycin, levofloxacin, and azithromycin showed that 7, 10, and 14 days administrations of 400 mg clarithromycin, 7, 10, and 14 days administrations of 300 mg levofloxacin, and a single dose of 1000 mg of azithromycin, would eradicate 100% of C. trachomatis for infections of uterine cervix. For pharyngeal infections, 10 and 14 days administrations of clarithromycin and levofloxacin were shown to eradicate 100% of C. trachomatis. However, the eradication rates for 7 days administrations of clarithromycin and levofloxacin were 83.9% and 86.2%, respectively, and the rate for a single dose of azithromycin was 85.0%. From these results, it was thought that more than 10 days of administrations of clarithromycin or fluoroquinolone antibacterial agents such as levofloxacin are necessary to treat pharyngeal chlamydial infection. Clinical significance of pharyngeal chlamydial infection is still not clear; however, this study have shown the need for more detailed investigations using culture assay, in corporation with doctors in otolaryngology and internal medicine.

Adult↗
PubMed2005

Diverse spatial, temporal, and sexual expression of recently duplicated androgen-binding protein genes in Mus musculus.

BACKGROUND: The genes for salivary androgen-binding protein (ABP) subunits have been evolving rapidly in ancestors of the house mouse Mus musculus, as evidenced both by recent and extensive gene duplication and by high ratios of nonsynonymous to synonymous nucleotide substitution rates. This makes ABP an appropriate model system with which to investigate how recent adaptive evolution of paralogous genes results in functional innovation (neofunctionalization). RESULTS: It was our goal to find evidence for the expression of as many of the Abp paralogues in the mouse genome as possible. We observed expression of six Abpa paralogues and five Abpbg paralogues in ten glands and other organs located predominantly in the head and neck (olfactory lobe of the brain, three salivary glands, lacrimal gland, Harderian gland, vomeronasal organ, and major olfactory epithelium). These Abp paralogues differed dramatically in their specific expression in these different glands and in their sexual dimorphism of expression. We also studied the appearance of expression in both late-stage embryos and postnatal animals prior to puberty and found significantly different timing of the onset of expression among the various paralogues. CONCLUSION: The multiple changes in the spatial expression profile of these genes resulting in various combinations of expression in glands and other organs in the head and face of the mouse strongly suggest that neofunctionalization of these genes, driven by adaptive evolution, has occurred following duplication. The extensive diversification in expression of this family of proteins provides two lines of evidence for a pheromonal role for ABP: 1) different patterns of Abpa/Abpbg expression in different glands; and 2) sexual dimorphism in the expression of the paralogues in a subset of those glands. These expression patterns differ dramatically among various glands that are located almost exclusively in the head and neck, where the sensory organs are located. Since mice are nocturnal, it is expected that they will make extensive use of olfactory as opposed to visual cues. The glands expressing Abp paralogues produce secretions (lacrimal and salivary) or detect odors (MOE and VNO) and thus it appears highly likely that ABP proteins play a role in olfactory communication.

Amino Acid Sequence↗
PubMed2003

mtDNA perspective of chromosomal diversification and hybridization in Peters' tent-making bat (Uroderma bilobatum: Phyllostomidae).

We compared sequence variation in the complete mitochondrial cytochrome-b gene with chromosomal and geographical variation for specimens of Peters' tent-making bat (Uroderma bilobatum). Three different chromosomal races have been described in this species: a 2n = 42 race from South America east of the Andes, a 2n = 44 from NW Central America and 2n = 38 from the rest of Central America and NW South America. The deepest nodes in the tree were found within the South American race (42 race), which is consistent with a longer history of this race. Average distance among races ranged from 2.5 to 2.9%, with the highest amount of intraracial variation found within the 2n = 42 race (1.7%), intermediate values within the 2n = 38 race (0.9%) and lowest within the 2n = 44 race (0.5%). Variation among chromosomal races accounted for over 55% of molecular variance, whereas variation among populations within races accounted for 6%. The 2n = 38 and 2n = 44 races hybridize in the coastal lowlands of Honduras, near the Gulf of Fonseca. Introgression between these two races is low (two introgressed individuals in 45 examined). Clinal variation across the hybrid zone for the cytochrome-b of U. bilobatum, is similar to clinal variation reported for chromosomes and isozymes of this species. Mismatch distribution analyses suggests that geographical isolation and karyological changes have interplayed in a synergistic fashion. Fixation of the alternative chromosomal rearrangements in geographical isolation and secondary contact is the most likely mechanism accounting for the hybrid zone between the 2n = 38 and 2n = 44 races. If a molecular clock is assumed, with rates ranging from 2.3 to 5.0% per million years, then isolation between these races occurred within the last million years, implying a relatively recent origin of the extant diversity in Uroderma bilobatum. None the less, the three chromosomal races probably represent three different biological species.

Animals↗
PubMed2002

Canopy light transmittance in Douglas-fir--western hemlock stands.

We measured vertical and horizontal variation in canopy transmittance of photosynthetically active radiation in five Pseudotsuga menziesii (Mirb.) Franco-Tsuga heterophylla (Raf.) Sarg. (Douglas-fir-western hemlock) stands in the central Cascades of southern Washington to determine how stand structure and age affect the forest light environment. The shape of the mean transmittance profile was related to stand height, but height of mean maximum transmittance was progressively lower than maximum tree height in older stands. The vertical rate of attenuation declined with stand age in both the overstory and understory. A classification of vertical light zones based on the mean and variance of transmittance showed a progressive widening of the bright (low variance and high mean) and transition (high variance and rapid vertical change) zones in older stands, whereas the dim zone (low variance and mean) narrowed. The zone of maximum canopy surface area in height profiles, estimated by inversion of transmittance profiles, changed from relatively high in the canopy in most young stands ("top-heavy") to lower in the canopy in older stands ("bottom-heavy"). In the understory, all stands had similar mean transmittances, but the spatial scale of variation increased with stand age and increasing crown size. The angular distribution of openness was similar in all stands, though the older stands were less open at all angles than the younger stands. Understory openness was generally unrelated to transmittance in the canopy above. Whole-canopy leaf area indices, estimated using three methods of inverting light measurements, showed little correspondence across methods. The observed patterns in light environment are consistent with structural changes occurring during stand development, particularly the diversification of crowns, the creation of openings of various sizes and the elaboration of the outer canopy surface. The ensemble of measurements has potential use in distinguishing forests of differing ages that have similar stature.

Light↗
PubMed2005

Risk factors for child under-nutrition with a human rights edge in rural villages of North Wollo, Ethiopia.

OBJECTIVE: To identify the factors associated with childhood under-nutrition in North Wollo, Ethiopia. DESIGN: A cross-sectional study. SETTING: Four purposefully selected rural villages (kebeles) in North Wollo zone of the Amhara Region, Ethiopia. SUBJECTS: One hundred-forty four sampled households with under five year old children (n=200) comprising of 96 male-headed, 24 female-headed and 24 landless with children aged between six and 59 months. MAIN OUTCOME MEASURES: Determinations of anthropometric measurements and various socio-economic factors. RESULTS: The overall prevalence rate of under nutrition as determined by stunting, underweight and wasting was 44.5%, 25.0% and 9.0% respectively with more preponderance among the toddlers. The proportion of under nutrition was higher in female-headed households. Shortage of farmland, lack of irrigation, dispossession of livestock, shortage of non-farm employment options, parental illiteracy, high number of children, water inadequacy, food taboos and wrong eating habits of families, poor child feeding practices, deprivation of health nutrition education as well as maternal attributes such as young motherhood, low body mass index and short stature of mothers influenced the nutritional status of the children. The prominent risk factors for undernutrition among children were dispossession of livestock, child food taboos and wrong eating habits of families, deprivation of health/nutrition education, short stature and early marriage of mothers. CONCLUSION: This study led to the conclusion that improvement of household resources through promotion of irrigation and initiation of income generating livelihood options can reverse the nutrition situation for better. Health and nutrition education focusing on appropriate child feeding, eradication of harmful traditional practices such as early marriage and inequitable intra-household food distribution, encouragement of family planning and nutrition interventions including food diversification is recommended.

Child Nutrition Sciences↗
PubMed1991

Diversification of glial lineages: a novel method to clone brain cells in vitro on nitrocellulose substratum.

We have developed a novel in vitro method to analyze the diversification of glial cells during development. The primary advantage of the approach is that glial lineages are formed in discrete clones on a nitrocellulose substratum where the relationship of the progeny is strictly defined. This method facilitates the comparison of a large complement of astrocyte and oligodendrocyte lineages under controlled conditions. Clones were formed by plating a brain dissociate on nitrocellulose at very low density (5,000-40,000 cells/154 mm2). However, growth depended on diffusible factors produced by brain cells growing under the nitrocellulose support at high density (feeder layer). The cloning efficiency of cells from mouse forebrain (P0) was 1-3%. This means we can detect 100,000 to 300,000 clonal progenitors in the dissociate (10(7) cells per forebrain) using the clonal culture technique. Cell phenotypes were determined by immunocytochemical staining with anti-glial fibrillary acidic protein (GFAP) to label astrocytes and anti-galactocerebroside (GC) and anti-myelin basic protein (MBP) to label oligodendrocytes. There was a remarkable diversity of glia represented in different lineages. The number of astrocyte clones was greater than the number of oligodendrocyte clones but combined their total was 90%. Clone sizes were distributed over a wide range, which indicated that growth rates varied. Clones appeared compact or dispersed but astrocyte clones exhibited three different morphologies-fibroblast-like, stellate, and elongated. Oligodendrocytes had different morphologies distinct from astrocytes. Although there were different glial lineages the cells in most clones were homogeneous, indicating the progeny had the same fate. However, a small number of the clones, approximately 2%, were heterogeneous and contained both astrocytes and oligodendrocytes. The application of this technique to glial lineages demonstrates that intrinsic factors have a role in determining cell fate since different clones formed under the same external conditions. Finally, these results are consistent with the existence of multiple glial progenitors or the continued presence of multipotential progenitors at the time of birth.

Animals↗
PubMed2000

A phylogenetic perspective on habitat shifts and diversity in the North American Enallagma damselflies.

Community ecologists are increasingly aware that the regional history of taxon diversification can have an important influence on community structure. Likewise, systematists recognize that ecological context can have an important influence on the processes of speciation and extinction that create patterns of descent. We present a phylogenetic analysis of 33 species of a North American radiation of damselflies (Zygoptera: Coenagrionidae: Enallagma Selys), which have been well studied ecologically, to elucidate the evolutionary mechanisms that have contributed to differences in diversity between larval habitats (lakes with and without fish predators). Analysis of molecular variation in 842 bp of the mitochondrial cytochrome oxidase I and II subunit and of the intervening Leu-tRNA and 37 morphological characters resulted in three well-defined clades that are only partially congruent with previous phylogenetic hypotheses. Molecular and morphological data partitions were significantly incongruent (p < .01). Lack of haplotype monophyly within species and small amounts of sequence divergence (< 1%) between related species in three of the four clades suggest that recent, and parallel, speciation has been an important source of community diversity. Reconstruction of habitat preference over the phylogeny suggests that the greater species diversity in fish-containing lake habitats reflects the recency of shifts into the fishless lake habit, although a difference in speciation or extinction rates between the two habitats is difficult to exclude as an additional mechanism.

Animals↗
PubMed1979

Evolutionary diversification of structure and function in the family of intracellular calcium-binding proteins.

The maximum parsimony method was used to reconstruct the genealogical history of the family of intracellular calcium-binding proteins represented by six major present-day lineages, three of which--calcium dependent modulator protein, heart and skeletal muscle troponin Cs, and alkali light chains of myosin--were found to share a closer kinship with one another than with the other lineages. Similarly, parvalbumins and regulatory light chains of myosin were depicted as more closely related, whereas the branch of intestinal calcium-binding protein proved to have the most distant separation. The computer-generated amino acid sequence for the common ancestor of these six lineages described a four domain protein in which each domain of approximately 40 amino acid residues had a mid-region. 12 residue segment that bound calcium and had properties most resembling those of the calcium dependent modulator protein. It could then be deduced that parvalbumins evolved by deletion of domain I, inactivation of calcium-binding properties in domain II, and acquisition of increased affinity for Ca++ and Mg++ in domains III and IV. Regulatory light chains of myosin lost the cation binding property from three domains, retaining it in I, whereas alkali light chains of myosin lost this ability from each of the four domains. In skeletal muscle troponin C all domains retained their calcium-binding activity; however, like parvalbumins, domains III and IV acquired high affinity properties. Cardiac troponin C lost its binding activity from domain I but otherwise resembled the skeletal muscle form. Finally, intestinal calcium-binding protein evolved by deletion of domains III and IV. Positive selection could be implicated in these evolutionary changes in that the rate of fixation of mutations substantially increased in the mid portions of those domains which were loosing calcium-binding activity. Likewise, when the cation binding sites were changing from low to high affinity, an accelerated rate of fixed mutations was observed. Once this new functional parameter was selected these regions showed a remarkable conservatism, as did those binding sites which were maintaining the lower affinity. Moreover even in sequence regions not directly involved in cation binding, the lineage of troponin C because very conservative over the past 300 million years, perhaps becuase of the necessity for maintaining specific interfaces in order for the molecule to interact with troponin I and T in a functional thin myofilament. A similar phenomenon was observed in domain II of the regulatory light chains of the myosin lineage suggesting a possible binding site with the heavy chain of myosin.

Amino Acid Sequence↗
PubMed2006

The production and release of living root cap border cells is a function of root apical meristem type in dicotyledonous angiosperm plants.

BACKGROUND AND AIMS: The root apical meristems (RAM) of flowering plant roots are organized into recognizable pattern types. At present, there are no known ecological or physiological benefits to having one RAM organization type over another. Although there are phylogenetic distribution patterns in plant groups, the possible evolutionary advantages of different RAM organization patterns are not understood. Root caps of many flowering plant roots are known to release living border cells into the rhizosphere, where the cells are believed to have the capacity to alter conditions in the soil and to interact with soil micro-organisms. Consequently, high rates of border cell production may have the potential to benefit plant growth and development greatly, and to provide a selective advantage in certain soil environments. This study reports the use of several approaches to elucidate the anatomical and developmental relationships between RAM organization and border cell production. METHODS: RAM types from many species were compared with numbers of border cells released in those species. In addition, other species were grown, fixed and sectioned to verify their organization type and capacity to produce border cells. Root tips were examined microscopically to characterize their pattern and some were stained to determine the viability of root cap cells. KEY RESULTS: The first report of a correlation between RAM organization type and the production and release of border cells is provided: species exhibiting open RAM organization produce significantly more border cells than species exhibiting closed apical organization. Roots with closed apical organization release peripheral root cap cells in sheets or large groups of dead cells, whereas root caps with open organization release individual living border cells. CONCLUSIONS: This study, the first to document a relationship between RAM organization, root cap behaviour and a possible ecological benefit to the plant, may yield a framework to examine the evolutionary causes for the diversification of RAM organization types across taxa.

Cucurbitaceae↗
PubMed2001

Take percentage and conditions of cultured epithelium were improved when basement membrane of the graft was maintained and anchoring mesh was added.

To achieve a higher take rate for epithelial grafts, this study investigated grafting techniques. Seventy-seven nude mice received flap grafting in which cultured human epithelium was grafted inside the flap, and 55 nude rats received transplantation of epithelium to a full-thickness skin defect. In each group, four models were studied, including model 1, in which epithelium was cultured with the conventional method; model 2, in which epithelium was cultured with fibrin gel to avoid sheet damage, then absorptive mesh was incorporated into the epithelium for anchoring to the graft bed; model 3, in which epithelium was cultured with fibrin gel and combined with absorptive mesh and artificial dermis containing fibroblasts; and model 4, in which the model 2 epithelium was grafted after artificial dermis was transplanted. The take for these models was evaluated grossly and histologically. The results show that the take percentage of models 2 and 3 was significantly higher than that of model 1 (conventional epithelium) and that there was no significant difference between model 3 (simultaneous grafting) and model 4 (two-step grafting). The difference in the take percentages of the grafts to the flap and to the full-thickness skin defect was also insignificant. In immunohistochemistry, human keratin appeared in all epidermis layers and diversification of the layer was observed in models 2, 3, and 4. In these three models, type IV collagen appeared in the basal layer and the formation of basal membrane was confirmed. These findings suggest that epithelia cultured on fibrin gel and combined with absorptive mesh could be used in a new technique for better, more stable take.

Absorbable Implants↗
PubMed1996

Required allosteric effector site for N-acetylglutamate on carbamoyl-phosphate synthetase I.

Carbamoyl-phosphate synthetase I (CPSase I) catalyzes the entry and rate-limiting step in the urea cycle, the pathway by which mammals detoxify ammonia. One facet of CPSase I regulation is a requirement for N-acetylglutamate (AGA), which induces an active enzyme conformation and does not participate directly in the chemical reaction. We have utilized labeling with carbodiimide-activated [14C]AGA to identify peptides 120-127, 234-237, 625-630, and 1351-1356 as potentially being near the binding site for AGA. Identification of peptide 1351-1356 confirms the previous demonstration (Rodriquez-Aparicio, L. B., Guadalajara, A. M., and Rubio, V.(1989) Biochemistry 28, 3070-3074) that the C-terminal region is involved in binding AGA. Identification of peptides 120-127 and 234-237 constitutes the first evidence that the N-terminal region of the synthetase is involved in ligand binding. Since peptides 631-638 and 1327-1348 have been identified near the ATP site of CPSase I (Potter, M. D., and Powers-Lee, S. G.(1992) J. Biol. Chem. 267, 2023-2031), the present finding of involvement of peptides 625-630 and 1351-1356 at an "allosteric" activator site was unexpected. The idea that portions of the AGA effector site might be derived from an ancestral glutamine substrate site via a gene duplication and diversification event was considered.

Allosteric Regulation↗
PubMed2003

The Sahara as a vicariant agent, and the role of Miocene climatic events, in the diversification of the mammalian order Macroscelidea (elephant shrews).

Although the Sahara is a major geographical feature of the African continent, its role in the diversification of animal species is not well understood. We present here a molecular phylogeny for members of the endemic African mammalian order Macroscelidea (elephant shrews) with molecular-clock calculations; this molecular phylogeny provides convincing evidence that the genus Elephantulus is diphyletic. Elephantulus rozeti, the only elephant shrew species that resides north of the Sahara, is the sister group of a species from a different genus (Petrodromus tetradactylus), which resides just south of the Sahara. The split between these taxa coincided with major Miocene climatic events, which triggered the cooling and aridification of midlatitude continental regions, and a shift in the Sahara from a tropical to an arid environment. Thus, the North African distribution of E. rozeti is not the result of dispersion from an eastern species of the genus, but instead the result of a vicariant event involving the formation of the Sahara. The splitting events involved with most Elephantulus species in our analysis appear to coincide with these climatic events. This coincidence suggests that the environmental consequences associated with this period played an important role in the radiation of this order of mammals. The strongly supported phylogeny provides compelling evidence for a complex history of mosaic evolution, including pronounced bradytelic morphological evolution in some lineages, accelerated morphological evolution in others, and a remarkably slow rate of evolution of the male reproductive structure.

Adaptation, Physiological↗
PubMed2004

Analysis of IgV gene mutations in B cell chronic lymphocytic leukaemia according to antigen-driven selection identifies subgroups with different prognosis and usage of the canonical somatic hypermutation machinery.

Cases of B-cell chronic lymphocytic leukaemia (B-CLL) with mutated (M) IgV(H) genes have a better prognosis than unmutated (UM) cases. We analysed the IgV(H) mutational status of B-CLL according to the features of a canonical somatic hypermutation (SHM) process, correlating this data with survival. In a series of 141 B-CLLs, 124 cases were examined for IgV(H) gene per cent mutations and skewing of replacement/silent mutations in the framework/complementarity-determining regions as evidence of antigen-driven selection; this identified three B-CLL subsets: significantly mutated (sM), with evidence of antigen-driven selection, not significantly mutated (nsM) and UM, without such evidence and IgV(H) gene per cent mutations above or below the 2% cut-off. sM B-CLL patients had longer survival within the good prognosis subgroup that had more than 2% mutations of IgV(H) genes. sM, nsM and UM B-CLL were also characterized for the biased usage of IgV(H) families, intraclonal IgV(H) gene diversification, preference of mutations to target-specific nucleotides or hotspots, and for the expression of enzymes involved in SHM (translesion DNA polymerase zeta and eta and activation-induced cytidine deaminase). These findings indicate the activation of a canonical SHM process in nsM and sM B-CLLs and underscore the role of the antigen in defining the specific clinical and biological features of B-CLL.

Adult↗
PubMed2006

Larval habits, host-plant associations, and speciation in nematine sawflies (Hymenoptera: Tenthredinidae).

Adaptive radiations consist of two intertwined processes, diversification of species and diversification of their ecological niches, but it is unclear whether there is a causal link between the processes. In phytophagous insects, ecological diversification mainly involves shifts in host-plant associations and in larval feeding habits (internal or external) on different plant parts, and several observations indicate that speciation is facilitated by host shifts. Data on host use in individual species suggest that internal feeders are less likely to colonize new hosts than external-feeding taxa and, consequently, increases in collective host ranges and species numbers should be slowed down in endophagous lineages. We tested these related hypotheses by using phylogenetic information to reconstruct the evolutionary history of larval resource use in the sawfly subfamily Nematinae, a group of 1000 plus species with a broad range of niches: the subfamily's combined host range includes over 20 plant families, and larvae may feed externally on leaves or needles, or internally, for example, in buds, fruits, leaves, or galls. The results show that: (1) Most internally feeding groups have evolved independently from external-feeding ancestors, but several distinct internal habits have appeared convergently multiple times; (2) Shifts among host taxa are clearly more common than changes in larval habits; (3) The majority of host switches have occurred among phylogenetically close plant groups, but many shifts are manifest among distantly related, ecologically proximate hosts; (4) Although external feeding characteristic of the common ancestor of Nematinae is associated with relatively high rates of host-shifting, internal feeders are very conservative in their host use; (5) In contrast, the effect of endophagy on speciation probabilities is more variable: net speciation rates are lowered in most internal-feeding groups, but a striking exception is found in species that induce galls on Salicaceae. The loose connection between collective host ranges and species diversity provides empirical support for theoretical models suggesting that speciation rates are a function of a complex interplay between "intrinsic" niche width and resource heterogeneity.

Animals↗
PubMed1996

Molecular evolution of ependymin and the phylogenetic resolution of early divergences among euteleost fishes.

The rate and pattern of DNA evolution of ependymin, a single-copy gene coding for a highly expressed glycoprotein in the brain matrix of teleost fishes, is characterized and its phylogenetic utility for fish systematics is assessed. DNA sequences were determined from catfish, electric fish, and characiforms and compared with published ependymin sequences from cyprinids, salmon, pike, and herring. Among these groups, ependymin amino acid sequences were highly divergent (up to 60% sequence difference), but had surprisingly similar hydropathy profiles and invariant glycosylation sites, suggesting that functional properties of the proteins are conserved. Comparison of base composition at third codon positions and introns revealed AT-rich introns and GC-rich third codon positions, suggesting that the biased codon usage observed might not be due to mutational bias. Phylogenetic information content of third codon positions was surprisingly high and sufficient to recover the most basal nodes of the tree, in spite of the observation that pairwise distances (at third codon positions) were well above the presumed saturation level. This finding can be explained by the high proportion of phylogenetically informative nonsynonymous changes at third codon positions among these highly divergent proteins. Ependymin DNA sequences have established the first molecular evidence for the monophyly of a group containing salmonids and esociforms. In addition, ependymin suggests a sister group relationship of electric fish (Gymnotiformes) and Characiformes, constituting a significant departure from currently accepted classifications. However, relationships among characiform lineages were not completely resolved by ependymin sequences in spite of seemingly appropriate levels of variation among taxa and considerably low levels of homoplasy in the data (consistency index = 0.7). If the diversification of Characiformes took place in an "explosive" manner, over a relatively short period of time this pattern should also be observed using other phylogenetic markers. Poor conservation of ependymin's primary structure hinders the design of efficient primers for PCR that could be used in wide-ranging fish systematic studies. However, alternative methods like PCR amplification from cDNA used here should provide promising comparative sequence data for the resolution of phylogenetic relationships among other basal lineages of teleost fishes.

Amino Acid Sequence↗
PubMed1982

Behavior during hippocampal microinfusions. I. Norepinephrine and diversive exploration.

Adult male Sprague-Dawley rats were surgically implanted with guide cannulas in the anterodorsal hippocampal formation. After recovery from surgery they were administered bilateral infusions into the dentate gyrus of D,L-norepinephrone (NE) at the rate of 0.025 microliter/min throughout a 40-min session in a holeboard/activity apparatus. The computerized holeboard system measured the animals' locomotor activity, stimulus responsivity, and response to novelty, and permitted the reconstruction and analysis of their sequential patterns of movement. The NE infusions failed to affect overall locomotion or holepoking, although group means were slightly elevated. Rearing frequency and duration were significantly increased, as were the number of different holes poked per 5-min epoch and the amount of time in and number of entries into the center region of the holeboard. The novel object reaction of NE-infused rats, measured as the increase in poke duration into holes with novel stimuli, was indistinguishable from that of saline-infused rats. The NE-infused rats exhibited more varied, widespread spatial distributions of sequential patterns of locomotor activity. A dose of the beta-adrenergic antagonist propranolol that was minimally effective when infused by itself blocked all of NE's affects when co-infused in the same solution. Infusions of the noradrenergic releasing agent tyramine mimicked NE's actions, whereas infusions of NE's relatively inactive stereoisomer D-NE or infusions into the overlying lateral ventrical failed to do so. Histological examination of dye-infused brains and microspectrofluorimetry of NE-infused brains treated using the Falck-Hillarp technique for the formaldehyde-induced fluorescence of monoamines indicated that spread of the infusate was confined to the dentate gyrus of the anterodorsal hippocampal formation. The behavioral profile of the NE-infused rats suggests a role for the noradrenergic input to the hippocampal formation in spontaneous environmental reconnaissance and the diversification of stimulus sampling-'diversive' exploration, as opposed to the inspection or 'specific' exploration of unfamiliar stimuli.

Animals↗
PubMed2007

Molecular phylogeny, evolution, and functional divergence of the LSD1-like gene family: inference from the rice genome.

The identification of LSD1-like genes in parasite, green algae, moss, pine, and monocot and dicot species allowed us to trace the phylogenetic history of this gene family. Computational analysis showed that the diversification of members of this family could be dated back to the early stage of plant evolution. The evolution of plant LSD1-like genes was possibly shaped by two duplication events. These proteins, which contain three copies of the LSD1 zinc finger (zf-LSD1) domain within their entire polypeptides and play crucial roles in modulating disease defense and cell death, resulted from the second duplication. A gain of zf-LSD1 domain model was reasonable for explaining the origination of three-zf-LSD1 domain-containing proteins. The zf-LSD1 domain phylogeny showed that the middle (M) and C-terminal (C) domains originated from a common ancestor; the N-terminal (N) domain might be more ancient than the former two. The divergence of the N, M, and C domains was well before the monocot-dicot split. Coevolution analysis revealed that four intramolecular domain pairs, including the N domain and the interregion between the M and the C domains (INTER2), the M and C domain, the N- and C-terminus, and the M domain and C-terminus, possibly coevolved during the evolution of three-zf-LSD1 domain-containing proteins. The three zf-LSD1 domains are evolutionary conserved. Thus, the differences at the N- and C-terminus would be crucial for functional specificity of LSD1 genes. Strong functional constraints should work on the zf-LSD1 domains, whereas reduced functional constraint was found in the INTER2 region. Functional divergence analysis showed that three-zf-LSD1 domain-containing proteins were significantly functionally divergent from those proteins containing only one zf-LSD1 domain, a result demonstrating that shifted evolutionary rates between the two clusters were significantly different from each other.

Amino Acid Sequence↗
PubMed1995

Mutation analyses of molecularly cloned satellite tobacco mosaic virus during serial passage in plants: evidence for hotspots of genetic change.

The high level of genetic diversity and rapid evolution of viral RNA genomes are well documented, but few studies have characterized the rate and nature of ongoing genetic change over time under controlled experimental conditions, especially in plant hosts. The RNA genome of satellite tobacco mosaic virus (STMV) was used as an effective model for such studies because of advantageous features of its genome structure and because the extant genetic heterogeneity of STMV has been characterized previously. In the present study, the process of genetic change over time was studied by monitoring multiple serial passage lines of STMV populations for changes in their consensus sequences. A total of 42 passage lines were initiated by inoculation of tobacco plants with a helper tobamovirus and one of four STMV RNA inocula that were transcribed from full-length infectious STMV clones or extracted from purified STMV type strain virions. Ten serial passages were carried out for each line and the consensus genotypes of progeny STMV populations were assessed for genetic change by RNase protection analyses of the entire 1,059-nt STMV genome. Three different types of genetic change were observed, including the fixation of novel mutations in 9 of 42 lines, mutation at the major heterogeneity site near nt 751 in 5 of the 19 lines inoculated with a single genotype, and selection of a single major genotype in 6 of the 23 lines inoculated with mixed genotypes. Sequence analyses showed that the majority of mutations were single base substitutions. The distribution of mutation sites included three clusters in which mutations occurred at or very near the same site, suggesting hot spots of genetic change in the STMV genome. The diversity of genetic changes in sibling lines is clear evidence for the important role of chance and random sampling events in the process of genetic diversification of STMV virus populations.

Biological Evolution↗