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At least 73 records · Page 4Linked to original sources
PubMed1989

Reproduction of Angola free-tailed bats (Tadarida condylura) and little free-tailed bats (Tadarida pumila) in Malawi (Central Africa) and elsewhere in Africa.

Angola free-tailed bats and little free-tailed bats occur in diverse habitats throughout most of Africa south of the Sahara. This study investigated the reproductive strategies and related biology of these species in Malawi where they were sympatric, and analysed data from elsewhere in Africa to show how the strategies varied along a gradient of habitats from approximately 12 degrees N to 25 degrees S. Both the Angola free-tailed bat and the little free-tailed bat were normally monotocous. Angola free-tailed bats invariably had 2 births/year, and the interval between consecutive births decreased with increasing latitude. When the interval was shortest (approximately 90 days) a post-partum oestrus occurred. Little free-tailed bats differed by having a shorter gestation (approximately 60 days), and the ability to have up to 5 births/year with a postpartum oestrus after each birth. The extent to which this potential is achieved varies with latitude and rainfall, mainly so that lactation can coincide with peaks in the abundance of food. The interaction between rainfall and reproductive characteristics results in the two species having patterns of reproduction which are sometimes similar, but more often different. Competition between the species is unlikely to be affected by differences in their reproduction.

Africa↗
PubMed1998

Expression of an ascidian gene in the tip of the tail of tail-bud-stage embryos.

The occurrence of tadpole-type larvae is one of the key events used to understand the origin and evolution of chordates, and the tail bud of chordate embryos is thought to be associated with formation of the tip of the tail. Although some transcriptional factor genes including Brachyury are expressed in the tail bud, no structural genes have been reported to be expressed there. We report here that an ascidian gene HrTT-1 is expressed exclusively in the tip of elongating tail of the tail-bud embryo. This gene encodes a possible secreted protein of 415 amino acids with the SCP/TPX family consensus sequences.

Amino Acid Sequence↗
PubMed1980

Ontogeny of oral behavior induced by tail pinch and electrical stimulation of the tail in rats.

In sated adult rats, a mild tail pinch induces stimulation-bound eating. Experiment 1 showed that during preweaning development the response to tail pinch changes in (a) type, from mouth opening to licking, gnawing, and eating; (b) duration, from intermittent to stimulation-bound; (c) direction, from indiscriminate licking to focused on food pellets; and (3) intensity of stimulation required to elicit it, from high to low. These changes were also observed with electrical stimulation of the tail (Experiment 2). In Experiment 3, tail stimulation did not induced suckling, which suggests that it does not activate all the behavioral patterns available to the pup or potentiate its responsiveness to all environmental stimuli. Furthermore, in contrast to food deprivation, it did not induce licking of milk in 5-day-old pups. It seems, therefore, that tail stimulation reveals a mode of control over ingestive response patterns that is different from the one exerted by food deprivation.

Animals↗
PubMed1990

The ventilatory movements of the avian pelvis and tail: function of the muscles of the tail region of the pigeon (Columba livia).

We have observed that birds of several different taxa move their tails in conjunction with sound production. These observations suggested to use that tail movements might also be associated with ventilation. Since we hypothesized that rhythmic movements of the tail and pelvis will ventilate the lungs, the activities of tail, epaxial and cloacal muscles of the pigeon were examined. Electromyograms (EMGs) were recorded from these muscles while ventilation was monitored. A muscle was considered to have ventilatory activity when the EMG activity had an obvious correlation to either inspiration or expiration. To obtain further information about the correlation between muscular activity and ventilation, we induced hyperpnea by administering 5% CO2. We report that the tail muscles that function as expiratory muscles are the M. caudofemoralis, the M. pubocaudalis internus and the M. pubocaudalis externus. We refer to these as the suprapubic abdominal muscles to distinguish them from the infrapubic (ventral) abdominal muscles. These muscles depress the pelvis and the uropygium and compress the thoracoabdominal cavity. M. transversus cloacae functions as an expiratory muscle by protracting the cloaca or by reducing its compliance. Of the suprapubic muscles we studied, the only inspiratory muscle is the axial muscle, M. longissimus dorsi. M. longissimus dorsi acts at the notarial-synsacral junction to elevate the pelvis. The rocking movements of the notarial-synsacral joint appear to be important for ventilation during conditions in which the sternum is 'fixed', such as when the bird is resting on its breast. We suggest that a division of labor may exist between the infra- and suprapubic abdominal muscles during ventilation such as panting or vocalization.

Abdominal Muscles↗
PubMed1997

Discharge of cutaneous afferent fibers innervating tail during passive tail movements in cats.

The discharge of cutaneous afferents innervating the tail were recorded from 145 single afferent fibers in 11 spinalized cats (conduction velocity: 32-58 m/s) during sinusoidal tail movements. Cutaneous afferent fibers were roughly classified into two groups, slowly-adapting (SA) and rapidly-adapting fibers (RA). The discharge patterns of afferent fibers during passive tail movements depended on the receptive field on tail skin. The results of the present experiments show that peripheral inputs from cutaneous afferent fibers sent various information regarding tail movement and position to central nervous systems.

Animals↗
PubMed2002

Matrix metalloproteinases mediate the dismantling of mesenchymal structures in the tadpole tail during thyroid hormone-induced tail resorption.

It has been suggested that a family of tissue remodelling enzymes called matrix metalloproteinases (MMPs) play a causal role in the process of tail resorption during thyroid hormone-induced metamorphosis of the anuran tadpole; however, this hypothesis has never been directly substantiated. We cloned two new Xenopus MMPs, gelatinase A (MMP-2) and MT3-MMP (MMP-16), and the MMP inhibitor TIMP-2. These clones were used along with several others to perform a comprehensive expression study. We show that all MMPs and TIMP-2 are dramatically induced in the resorbing tail during spontaneous metamorphosis and are spatially coexpressed, primarily in the remodelling mesenchymal tissues. By Northern blotting, we show that all the examined MMPs/TIMP-2 are also induced by treatment of organ-cultured tails with thyroid hormone (T(3)). Using the organ culture model, we provide the first direct evidence that MMPs are required for T(3)-induced tail resorption by showing that a synthetic inhibitor of MMP activity/expression can specifically retard the resorption process. By gelatin zymography, we also show T(3) induction of a fifth MMP, preliminarily identified as gelatinase B (GelB; MMP-9). Moreover, T(3) not only induces MMP/TIMP expression but also MMP activation, and we provide evidence that TIMP-2 participates in the latter process. These findings suggest that MMPs and TIMPs act in concert to effect the dismantling of mesenchymal structures during T(3)-induced metamorphic tadpole tail resorption.

Amino Acid Sequence↗
PubMed1995

Kidney structure and function of obligate and facultative hibernators: the white-tailed prairie dog (Cynomys leucurus) and the black-tailed prairie dog (Cynomys ludovicianus).

The white-tailed prairie dog is an obligate hibernator that enters a heterothermic phase when maintained in the cold with low intensity light and ad libitum food and water. The black-tailed prairie dog (a facultative hibernator) will not hibernate under similar conditions. It has been suggested that the black tailed prairie dog remains active during the winter because it can conserve water more effectively due to a more efficient kidney. The present study revealed no significant differences between the species in renal morphology: relative medullary thickness, nephron heterogeneity, renal vasculature, or fornix dimensions, all of which are structures associated with the urinary concentrating mechanism. In addition, there was no difference in number of nephrons between the two species. The black-tailed prairie dog does produce a more concentrated urine when food and water deprived. However, this difference was not observed when the animals were salt loaded. The water-deprivation and salt-loading experiments suggest that the higher urine osmolality produced by the back-tailed prairie dog during fasting is a result of a higher urea load due to a greater protein catabolism and not because of a differential capacity to concentrate urine.

Adaptation, Physiological↗
PubMed2001

Probing the donor-acceptor proximity on the physicochemical properties of porphyrin-fullerene dyads: "tail-on" and "tail-off" binding approach.

A new approach of probing proximity effects in porphyrin-fullerene dyads by using an axial ligand coordination controlled "tail-on" and "tail-off" binding mechanism is reported. In the newly synthesized porphyrin-fullerene dyads for this purpose, the donor-acceptor proximity is controlled either by temperature variation or by an axial ligand replacement method. In o-dichlorobenzene, 0.1 M (TBA)ClO(4), the synthesized zincporphyrin-fullerene dyads exhibit seven one-electron reversible redox reactions within the accessible potential window of the solvent and the measured electrochemical redox potentials and UV-visible absorption spectra reveal little or no ground-state interactions between the C(60) spheroid and porphyrin pi-system. The proximity effects on the photoinduced charge separation and charge recombination are probed by both steady-state and time-resolved fluorescence techniques. It is observed that in the "tail-off" form the charge-separation efficiency changes to some extent in comparison with the results obtained for the "tail-on" form, suggesting the presence of some through-space interactions between the singlet excited zinc porphyrin and the C(60) moiety in the "tail-off" form. The charge separation rates and efficiencies are evaluated from the fluorescence lifetime studies. The charge separation via the singlet excited states of zinc porphyrin in the studied dyads is also confirmed by the quick rise-decay of the anion radical of the C(60) moiety within 20 ns. Furthermore, a long-lived ion pair with lifetime of about 1000 ns is also observed in the investigated zinc porphyrin-C(60) dyads.

Journal Article↗
PubMed1981

Dual functions of bacteriophage T4D gene 28 product: structural component of the viral tail baseplate central plug and cleavage enzyme for folyl polyglutamates. I. Identification of T4D gene 28 product in the tail plug.

The T4D bacteriophage gene 28 product is a component of the central plug of the tail baseplate, as shown by the following two independent lines of evidence. (i) A highly sensitive method for radioactive labeling of only tail baseplate plug components was developed. These labeled plug components were incorporated by a complementation procedure into new phage particles and were analyzed by radioautography after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Three new structural proteins were found in addition to the three known tail plug proteins (i.e., gP29, gP27, and gP5). One of the three newly identified components had a molecular weight of 24,000 to 25,000 and appeared to be a product of T4D gene 28. (ii) Characterization of mutants of Escherichia coli bacteriophage T4D which produced altered gene 28 products also indicated that the gene 28 product was a viral tail component. T4D 28(ts) phage particles produced at the permissive temperature had altered heat labilities compared with parent T4D particles. We isolated a single-step temperature revertant of T4D 28(ts) and found that it produced phage particles which phenotypically resembled the original T4D particles. Since the properties of the phage baseplate components usually determine heat lability, these two changes in physical stability after two sequential single mutations in gene 28 supported the other evidence that the gene 28 product was a viral baseplate component. Also, compared with parent T4D particles, T4D 28(ts) and T4D 28am viral particles adsorbed at different rates to various types of host cells. In addition, T4D 28(ts) particles exhibited a different host range than parent T4D particles. This T4D mutant formed plaques with an extremely low efficiency on all E. coli K-12 strains tested. We found that although T4D 28(ts) particles adsorbed rapidly and irreversibly to the E. coli K-12 strains, as judged by gene rescue experiments, these particles were not able to inject their DNA into the E. coli K-12 strains. On the other hand, the T4D 28(ts) revertant had a plating efficiency on E. coli K-12 strains that was quite similar to the plating efficiency of the original parent, T4D. These properties of phage particles containing an altered gene 28 product supported the analytical finding that the gene 28 product is a structural component of the central plug of the T4D tail baseplate. They also indicated that this component plays a role in both host cell recognition and viral DNA injection.

Adsorption↗
PubMed1998

Trypanosoma cruzi infection of free-ranging lion-tailed macaques (Macaca silenus) and ring-tailed lemurs (Lemur catta) on St. Catherine's Island, Georgia, USA.

Free-ranging Old World primates released on St. Catherine's Island, Georgia (USA), were tested for infection with Trypanosoma cruzi as part of a study of the epizootiology of sylvatic T. cruzi in the southeastern USA. The parasite was observed in liver infusion tryptose medium cultures of blood from seven of 11 lion-tailed macaques (Macaca silenus) and one of 19 ring-tailed lemurs (Lemur catta). Cultures of blood from 10 black and white ruffed lemurs (Varecia variegata) were all negative. Analysis of small subunit ribosomal RNA gene polymorphisms detected using polymerase chain reaction techniques indicates that the parasites isolated from both the lion-tailed macaques and the ring-tailed lemur are probably the same as T. cruzi parasites isolated from raccoons (Procyon lotor) trapped on St. Catherine's Island and other locations in the southeastern USA. Foraging lion-tailed macaques were observed to handle and partially consume specimens of Triatoma sanguisuga, the triatomine bug thought to be a vector of T. cruzi in the southeastern USA. Oral transmission of the parasite may have occurred as a result of this behavior.

Animals↗
PubMed1990

Structural studies of the contractile tail sheath protein of bacteriophage T4. 1. Conformational change of the tail sheath upon contraction as probed by differential chemical modification.

Differential chemical modifications of tyrosine residues of the tail sheath protein, gp18, were performed to elucidate the structural change of the tail sheath upon contraction. Tyrosine residues of monomeric gp18, extended tail sheath, and contracted tail sheath were nitrated by tetranitromethane, and the modified tyrosine residues in each state of the sheath protein were identified by peptide mapping and amino acid sequence analyses of the isolated peptides. Of 31 tyrosine residues in gp18 monomer or in the extended sheath, 12 or 13 residues (Tyr63 and/or -73, -225, -254, -270, -304, -455, -460, -493, -532, -535, -569, and -590) were modified. When photo-CIDNP difference spectra were measured with monomeric gp18, two peaks, which are due to highly exposed tyrosine residues on the molecular surface of gp18, were observed. These two peaks disappeared when the monomeric gp18 was nitrated. With contracted sheath, however, only eight tyrosine residues (Tyr225, -254, -270, -455, -460, -493, -532, and -535) were nitrated on the contracted sheath. Chemical modification of cysteine residues by sulfhydryl group specific reagent ABD-F [(4-aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole] revealed that, among five cysteine residues, Cys377, Cys477, and Cys607 have a sulfhydryl group. Cys402 and Cys406 were modified only under reducing conditions, which strongly suggested the presence of a disulfide bond between these two residues.

Chemical Phenomena↗
PubMed1997

Mapping in the region of Danforth's short tail and the localization of tail length modifiers.

We have used an interspecific backcross to generate a detailed genetic map around the mouse tail and kidney developmental mutation Danforth's short tail (Sd). The map includes 14 simple sequence repeat (SSR) markers and four genes in a 5-cM region encompassing Sd. In addition we have used a DNA pooling approach to carry out a genome scan to localize quantitative trait loci (QTL) that modify the tail length of Sd progeny of the backcross. This has allowed us to identify a major QTL on chromosome 10 in the region of nodal and three other putative tail length QTL on chromosomes 1, 9, and 18.

Alleles↗
PubMed1994

Lamb tail docking: a controlled field study of the effects of tail amputation on health and productivity.

A detailed study of the effects of tail docking on lamb health and productivity was prompted by current concern about the welfare aspects of lamb tail amputation. Using a controlled field trial, comparing over 3000 docked and undocked lambs on seven farms, the effects of tail docking on mortality, blowfly strike and production variables were examined. The incidence of blowfly strike was strongly and consistently higher in undocked than docked lambs (rate ratio 6.03, 95 per cent confidence interval (CI) 2.99 to 12.19 for male lambs and 4.25, 95 per cent CI 2.25 to 8.01 for female lambs). The incidence of faecal soiling of the breech was slightly higher in undocked lambs and was identified as an important independent risk factor for blowfly strike. Both the mortality and production parameters were similar for docked and undocked lambs. It was concluded that tail docking protected against blowfly strike, with little evidence of any detrimental effect on lamb mortality and production.

Amputation, Surgical↗
PubMed1995

Analysis of FGF function in normal and no tail zebrafish embryos reveals separate mechanisms for formation of the trunk and the tail.

To analyse the roles of FGF activity and brachyury during gastrulation we have directly compared the consequences of inhibition of FGF-receptor signalling with the phenotype of the zebrafish brachyury mutant, no tail (ntl). We show that expression of ntl is regulated by FGF and that inhibition of FGF receptor-signalling leads to complete loss of the trunk and tail. Since the ntl mutant lacks the tail and notochord but has an otherwise normal trunk, this demonstrates that trunk development is dependent upon an unidentified gene, or set of genes, referred to as no trunk (ntk) which is regulated by FGF. We propose a model to explain the FGF-dependent regulation of ntl and ntk that accounts for the above phenotypes. Consistent with this model, over-expression of eFGF led to suppression of anterior fates and development of trunk and tail derivatives only. In addition, widespread activation of convergence and extension movements resulted in the formation of multiple axis-like structures. Expression of eve1 and cad1 was also regulated by FGF activity, suggesting that during gastrulation FGF activity is normally restricted to the germ ring where these genes, and ntl, are expressed. Taken together these data suggest that the germ ring acts as a posteriorising centre during AP patterning, mediated by FGF activity in this tissue.

Animals↗
PubMed1991

Primary structure of a collagenic tail peptide of Torpedo acetylcholinesterase: co-expression with catalytic subunit induces the production of collagen-tailed forms in transfected cells.

The asymmetric forms of cholinesterases are synthesized only in differentiated muscular and neural cells of vertebrates. These complex oligomers are characterized by the presence of a collagen-like tail, associated with one, two or three tetramers of catalytic subunits. The collagenic tail is responsible for ionic interactions, explaining the insertion of these molecules in extracellular basal lamina, e.g. at neuromuscular endplates. We report the cloning of a collagenic subunit from Torpedo marmorata acetylcholinesterase (AChE). The predicted primary structure contains a putative signal peptide, a proline-rich domain, a collagenic domain, and a C-terminal domain composed of proline-rich and cysteine-rich regions. Several variants are generated by alternative splicing. Apart from the collagenic domain, the AChE tail subunit does not present any homology with previously known proteins. We show that co-expression of catalytic AChE subunits and collagenic subunits results in the production of asymmetric, collagen-tailed AChE forms in transfected COS cells. Thus, the assembly of these complex forms does not depend on a specific cellular processing, but rather on the expression of the collagenic subunits.

Acetylcholinesterase↗
PubMed1995

Effect of protamine on the solubilization of collagen-tailed acetylcholinesterase: potential heparin-binding consensus sequences in the tail of the enzyme.

Asymmetric acetylcholinesterase (AChE) contains three tetrameric sets of catalytic subunits disulfide-linked to structural subunits of a collagenic tail. This form is localized in the basement membrane zone of the neuromuscular junction, where it interacts with proteoglycans. It has been described that heparin-binding domains of many proteins contains clusters of basic residues. Here we show that protamine--a highly basic protein--specifically solubilizes asymmetric AChE from the rat neuromuscular junction, starting at 25 micrograms/ml and reaching a plateau at 250 micrograms/ml protamine. We also show that protamine was able to displace AChE bound to heparin-agarose. Two synthetic peptides corresponding to the sequence of the collagenic tail polypeptide also release the enzyme. Finally, we propose that two heparin-binding consensus sequences (-B-B-X-B-) are present in the tail of AChE. Our results indicate that clusters of basic residues are responsible for the interaction of the collagen-tailed AChE with proteoglycans.

Acetylcholinesterase↗
PubMed1983

Attachment of tail fibers in bacteriophage T4 assembly. Identification of the baseplate protein to which tail fibers attach.

A phage-neutralizing rabbit antiserum collected after immunization with tail-fiberless bacteriophage T4 particles was adsorbed with complete T4 phage. The resulting adsorbed serum inhibited tail fiber attachment in vitro. To identify the antigens against which this inhibitory activity was directed, blocking experiments were carried out with the adsorbed serum. Isolated complete baseplates and mutant-infected-cell extracts lacking known baseplate gene products but containing gene 9 product showed similar high levels of blocking activity. By contrast, both tail-fiberless particles lacking gene 9 product and infected-cell extracts made with gene 9 mutants showed 30-fold to 100-fold lower blocking activity. These results strongly support the conclusion that gene 9 product is the baseplate protein to which tail fibers attach.

Antigens, Viral↗
PubMed2005

Effect of VEGF on tail artery interpositional loop (TAIL) flap: a rodent model for flap prefabrication.

The authors introduce an experimental model of flap prefabrication, the tail artery interpositional loop (TAIL) flap. In this model, an arterial segment from a rat tail is used to create an arteriovenous (A-V) fistula. This fistula is positioned beneath the abdominal skin flap to vascularize the overlying tissue, and a barrier of Silastic sheeting is placed below the fistula to prevent vascular ingrowth from the underlying bed. The efficacy of this new model was tested by investigating the effect of a single topical application of recombinant human VEGF (165). Treatment and control groups each contained 20 animals. In the control group, mean survival skin areas at 1, 2, 3, and 4 weeks were 12.5 percent, 27 percent, 35 percent, and 50 percent, respectively. In the VEGF (165)-treated group, survival rates were 14.8 percent, 37 percent, 48 percent, and 74.3 percent, respectively. Statistically significant differences were noted between the two groups at the 2-week ( p = 0.047), 3-week ( p = 0.048), and 4-week ( p = 0.023) time intervals. The authors conclude that the TAIL flap is a novel and useful animal model to study flap prefabrication.

Animals↗