Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Tail”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources
PubMed2002

The many tales of a tail: carboxyl-terminal tail heterogeneity specializes histone H2A variants for defined chromatin function.

For many years, histones were considered to be passive structural components of eukaryotic chromatin. Experimental evidence that has accumulated during the past few years indicates that in addition to their structural role, histones play a very important functional role and that they can operate as epigenetic markers. This notion has rekindled the interest in histone variants and their participation in the processes of chromatin activation and inactivation. Recent papers have focused their attention on histone H2A variants. The variants of this overlooked histone participate in many biological processes ranging from transcriptional activation to DNA repair, meiosis, and apoptosis. A nucleosome containing at least one of these variants has been crystallized and biophysically characterized in solution. From all these results, a new concept has started to emerge, which supports the notion that the functional roles of H2A variants are exerted through alterations in chromatin stability and folding that result from the structural variation at the carboxyl-terminal end of this histone.

Amino Acid Sequence↗
PubMed1999

Cig30 and Pitx3 genes are arranged in a partially overlapping tail-to-tail array resulting in complementary transcripts.

The mouse Cig30 gene codes for a 30-kDa membrane glycoprotein, which appears to have a role in the recruitment of brown adipose tissue. To elucidate the structure of the Cig30 gene, we have isolated a lambda phage genomic DNA clone containing the entire mouse gene and found that Cig30 consists of four exons that are spread over 4 kilobase pairs of genomic sequence. Using a fluorescence in situ hybridization assay and interspecific backcross panel mapping, we have localized the Cig30 locus to the distal region of mouse chromosome 19, between the Tlx1 and Ins1 loci. Sequencing of the corresponding lambda clone to completion revealed that the insert contained yet another gene in the opposite orientation. It turned out to be the newly identified homeobox gene Pitx3. Interestingly, the genes are very tightly linked, so that the 3' ends of their transcripts are complementary. Thus, our results provide evidence for bidirectional transcription of a several hundred base pair-long DNA region as a result of the extremely tight linkage between Cig30 and Pitx3.

Acetyltransferases↗
PubMed2006

Distinct requirements for translocation of the N-tail and C-tail of the Escherichia coli inner membrane protein CyoA.

Inner membrane proteins (IMPs) of Escherichia coli use different pathways for membrane targeting and integration. YidC plays an essential but poorly defined role in the integration and folding of IMPs both in conjunction with the Sec translocon and as a Sec-independent insertase. Depletion of YidC only marginally affects the insertion of Sec-dependent IMPs, whereas it blocks the insertion of a subset of Sec-independent IMPs. Substrates of this latter "YidC-only" pathway include the relatively small IMPs M13 procoat, Pf3 coat protein, and subunit c of the F(1)F(0) ATPase. Recently, it has been shown that the steady state level of the larger and more complex CyoA subunit of the cytochrome o oxidase is also severely affected upon depletion of YidC. In the present study we have analyzed the biogenesis of the integral lipoprotein CyoA. Collectively, our data suggest that the first transmembrane segment of CyoA rather than the signal sequence recruits the signal recognition particle for membrane targeting. Membrane integration and assembly appear to occur in two distinct sequential steps. YidC is sufficient to catalyze insertion of the N-terminal domain consisting of the signal sequence, transmembrane segment 1, and the small periplasmic domain in between. Translocation of the large C-terminal periplasmic domain requires the Sec translocon and SecA, suggesting that for this particular IMP the Sec translocon might operate downstream of YidC.

Blotting, Western↗
PubMed2000

Two-tailed versus one-tailed base rates of discrepancy scores in the WAIS-III.

Tables included in the WAIS-III report the frequency of discrepancies between IQ and index scores independent of the directionality of the score. If an examiner does not have any a priori hypothesis about which skill may be more developed and which skills may be weaknesses, it is appropriate to use these tables as they are. In this case the examiner would be looking for unusually large discrepancies between scores irrespective of direction. When an examiner has a hypothesis about which skills may be weaknesses and strengths for an individual, the frequencies that are based upon an absolute value of the discrepancy will cause examiners to overestimate the frequency of the occurrence of the discrepancy score in question. Sattler and Ryan (1998) and Tulsky, Zhu, and Vasquez (1998) suggested dividing the frequencies reported in the WAIS-III tables in half to obtain the correct base rate. This suggestion is tested in this paper. New observed frequency tables were derived from the WAIS-III and WMS-III standardization samples and these frequencies were compared against the estimated frequencies using the method described by Sattler and Ryan (1998) and Tulsky et al. (1998). The differences between these two methods were calculated and are, for the most part, insignificant. In light of the similarity between the methods, the implications of using observed frequencies versus estimated frequencies is discussed.

Adolescent↗
PubMedDate not supplied

Factors affecting tailing in ethylene oxide sterilization part 1: When tailing is an artifact... and scientific deficiencies in ISO 11135 and EN 550.

Current approaches for validation of EtO sterilization cycles identified in ISO 11135 and EN 550 are scientifically deficient and result in full cycle times that are too short. This review article identifies the scientific flaws promulgated in the standards that lead to overestimation of process lethality. The reasons for these deficiencies are design-of-experiment errors that either fail to mathematically account for lag factors or that treat dissimilar samples as a single statistical sample set. Industry's movement toward parametric release, based on erroneous assumptions where exposure time rather than equivalent time is used, may create serious problems. The authors discuss these errors in detail, as well as reasonable methods for correcting them based on formulae for integrated lethality. Application of these methods will allow more accurate calculations of process lethality that are supported by biological data and appropriate mathematical analyses.

Colony Count, Microbial↗
PubMed1985

[Arterial vascularization of the tail of the pancreas with special reference to the relation of the tail and body vessels].

The cauda pancreatis has a characteristic pattern of vascularization. Among the big arterial stems surrounding it, up to 4 arteries, 'caudal arteries', nourish the arterial system of the cauda. These stems originate especially in the Arteria gastroepiploica sinistra and in the lower main splenic branch of the Arteria lienalis. The vascular relations between corpus and cauda can be of different kinds. Five basic types of relations can be identified: type I: the cauda is supplied exclusively by caudal arteries; type II: at least one caudal artery anastomoses with the vessels of the corpus; type III: the cauda is supplied both by the caudal arteries and by vessels of the corpus (non-anastomosing); type IV: combined forms of blood supply by caudal arteries and corpus arteries by way of anastomoses and non-anastomosing vessels are found; type V: the cauda is supplied exclusively be vessels stemming from the corpus. In each of these five types, individual vessels supplying the cauda can assume the function of a terminal vessel.

Aged↗
PubMed1998

Tailed bacteriophages: the order caudovirales.

Tailed bacteriophages have a common origin and constitute an order with three families, named Caudovirales. Their structured tail is unique. Tailed phages share a series of high-level taxonomic properties and show many facultative features that are unique or rare in viruses, for example, tail appendages and unusual bases. They share with other viruses, especially herpesviruses, elements of morphogenesis and life-style that are attributed to convergent evolution. Tailed phages present three types of lysogeny, exemplified by phages lambda, Mu, and P1. Lysogeny appears as a secondary property acquired by horizontal gene transfer. Amino acid sequence alignments (notably of DNA polymerases, integrases, and peptidoglycan hydrolases) indicate frequent events of horizontal gene transfer in tailed phages. Common capsid and tail proteins have not been detected. Tailed phages possibly evolved from small protein shells with a few genes sufficient for some basal level of productive infection. This early stage can no longer be traced. At one point, this precursor phage became perfected. Some of its features were perfect enough to be transmitted until today. It is tempting to list major present-day properties of tailed phages in the past tense to construct a tentative history of these viruses: 1. Tailed phages originated in the early Precambrian, long before eukaryotes and their viruses. 2. The ur-tailed phage, already a quite evolved virus, had an icosahedral head of about 60 nm in diameter and a long non-contractile tail with sixfold symmetry. The capsid contained a single molecule of dsDNA of about 50 kb, and the tail was probably provided with a fixation apparatus. Head and tail were held together by a connector. a. The particle contained no lipids, was heavier than most viruses to come, and had a high DNA content proportional to its capsid size (about 50%). b. Most of its DNA coded for structural proteins. Morphopoietic genes clustered at one end of the genome, with head genes preceding tail genes. Lytic enzymes were probably coded for. A part of the phage genome was nonessential and possibly bacterial. Were tailed phages general transductants since the beginning? 3. The virus infected its host from the outside, injecting its DNA. Replication involved transcription in several waves and formation of DNA concatemers. Novel phages were released by burst of the infected cell after lysis of host membranes by a peptidoglycan hydrolase (and a holin?). a. Capsids were assembled from a starting point, the connector, and around a scaffold. They underwent an elaborate maturation process involving protein cleavage and capsid expansion. Heads and tails were assembled separately and joined later. b. The DNA was cut to size and entered preformed capsids by a headful mechanism. 4. Subsequently, tailed phages diversified by: a. Evolving contractile or short tails and elongated heads. b. Exchanging genes or gene fragments with other phages. c. Becoming temperate by acquiring an integrase-excisionase complex, plasmid parts, or transposons. d. Acquiring DNA and RNA polymerases and other replication enzymes. e. Exchanging lysin genes with their hosts. f. Losing the ability to form concatemers as a consequence of acquiring transposons (Mu) or proteinprimed DNA polymerases (phi 29). Present-day tailed phages appear as chimeras, but their monophyletic origin is still inscribed in their morphology, genome structure, and replication strategy. It may also be evident in the three-dimensional structure of capsid and tail proteins. It is unlikely to be found in amino acid sequences because constitutive proteins must be so old that relationships were obliterated and most or all replication-, lysogeny-, and lysis-related proteins appear to have been borrowed. However, the sum of tailed phage properties and behavior is so characteristic that tailed phages cannot be confused with other viruses.

Caudovirales↗
PubMed1983

Mechanoafferent neurons innervating tail of Aplysia. II. Modulation by sensitizing stimulation.

The tail-withdrawal reflex of Aplysia can be sensitized by weak stimulation of a site outside the site used to test the reflex or by repeatedly stimulating the test site itself. The sensitization of tail-withdrawal responses is associated with enhanced activation of the tail motor neurons and heterosynaptic facilitation of the monosynaptic connections between the tail sensory neurons and tail motor neurons. This synaptic facilitation can occur under conditions in which neither posttetanic potentiation nor generalized changes in postsynaptic input resistance contribute to the facilitation. In addition to producing monosynaptic excitatory postsynaptic potentials (EPSPs), action potentials in tail sensory neurons often recruit longer latency polysynaptic input to the tail motor neurons during sensitization. Strong, noxious tail shock similar in intensity to that used previously for sensitization and aversive classical conditioning of other responses in Aplysia produces more heterosynaptic facilitation than does weak sensitizing stimulation. Heterosynaptic facilitation builds up progressively with multiple trials and lasts for hours. Very strong shocks to the tail can change the response characteristics of tail sensory neurons so that a prolonged, regenerative burst of spikes is elicited by a brief intracellular depolarizing pulse. This bursting response produced by sensitizing stimulation has not been described previously in Aplysia sensory neurons and can greatly amplify the synaptic input to tail motor neurons from the sensory neurons. In addition, strong shocks to the tail increase the duration and magnitude of individual sensory neuron action potentials. Sensitizing tail stimulation usually produces long-lasting depolarization of the tail motor neurons and often long-lasting hyperpolarization of the tail sensory neurons. The tail motor and sensory neurons show both increases and decreases of input resistance following sensitizing stimulation. However, the small, occasional increases in input resistance of the motor neuron are insufficient to explain the heterosynaptic facilitation produced by sensitizing stimulation. Serotonin (5-HT) application can mimic many of the effects of sensitizing tail shock, including facilitation of both tail withdrawal and the monosynaptic connections between tail sensory and motor neurons, hyperpolarizing and depolarizing responses in the tail sensory neurons, and an increase in the duration and magnitude of the sensory neuron action potential. In the nearly isolated sensory neuron soma, 5-HT usually produces a slow, decreased conductance depolarizing response, suggesting that the 5-HT-induced hyperpolarizing response see

Animals↗
PubMed1990

Mechanism of length determination in bacteriophage lambda tails.

The mechanism of length determination in bacteriophage lambda tails is discussed as a model for regulation in protein assembly systems. The lambda tail is a long flexible tube ending in a conical part and a single tail fiber. Its length is exactly determined in the sense that the number of major tail protein (gpV) molecules, which comprise more than 80% of the mass of the tail, is exactly the same in all tails. Assembly of gpV is regulated by the initiator complex, which contains the tail fiber and the conical part, and by the terminator protein gpU. There are two key points in the assembly of gpV with respect to length determination. (1) Assembly of gpV on the initiator pauses at the correct tail length. Binding of gpU to the tail only fixes the pause firmly. (2) When the tail length is too short, binding of gpU to tails is inhibited. Deletions and a duplication (both in frame) in gene H, which codes for one of the proteins in the initiator, result in production of phage particles with altered tail length. Moreover, the tail length is roughly proportional to the length of the mutated versions of gene H. This shows that the tail length is measured by the length of gene H protein (gpH), which seems to be approximately as long as the tail tube, if extended like a thread, according to secondary structure prediction (alpha-helices connected by other structures). Various pieces of evidence show that about six molecules of gpH are attached to the remaining portion of the initiator by the C-terminal part and folded into a somewhat compact form, while they are elongated as they are enclosed in the tail tube during assembly of gpV. Unlike interaction between the length-measuring genome RNA and the coat protein of tobacco mosaic virus, the major tail protein gpV does not bind specifically to the ruler protein gpH. Rather, gpH determines the tail length by inhibiting the binding of gpU to short tails and by signalling the pause when the correct tail length is attained.

Bacteriophage lambda↗
PubMed2001

Lift generation by the avian tail.

Variation with tail spread of the lift generated by a bird tail was measured on mounted, frozen European starlings (Sturnus vulgaris) in a wind tunnel at a typical air speed and body and tail angle of attack in order to test predictions of existing aerodynamic theories modelling tail lift. Measured lift at all but the lowest tail spread angles was significantly lower than the predictions of slender wing, leading edge vortex and lifting line models of lift production. Instead, the tail lift coefficient based on tail area was independent of tail spread, tail aspect ratio and maximum tail span. Theoretical models do not predict bird tail lift reliably and, when applied to tail morphology, may underestimate the aerodynamic optimum tail feather length. Flow visualization experiments reveal that an isolated tail generates leading edge vortices as expected for a low-aspect ratio delta wing, but that in the intact bird body-tail interactions are critical in determining tail aerodynamics: lifting vortices shed from the body interact with the tail and degrade tail lift compared with that of an isolated tail.

Animals↗
PubMed1983

Mechanoafferent neurons innervating tail of Aplysia. I. Response properties and synaptic connections.

Mechanical, chemical, or electrical stimulation of the tail elicits a short-latency (less than 1 s) tail-withdrawal reflex that is graded with the intensity of the stimulus. The tail-withdrawal reflex is not elicited by stimulation of parts of the body outside of the tail region. Mechanoafferent neurons innervating the tail are located in a small subcluster within a large, homogeneous group of medium-size (40-80 micron) cells on the ventrocaudal (VC) surface of each pleural ganglion. The tail sensory neurons within this large VC cluster are activated by tactile pressure or by electrical stimulation of discrete regions of the tail. They adapt slowly to maintained stimulation and sometimes respond to stimulus offset as well. Both mechanical and electrical stimuli produce responses that are graded with the intensity of the stimulus. Cells in the VC cluster appear to be primary mechanoreceptors because they have axons in peripheral nerves (including nerves innervating the tail), they exhibit action potentials lacking prepotentials in response to tactile stimulation, and these action potentials are still produced by cutaneous stimulation when peripheral and central chemical synaptic transmission is blocked. Stimulation of fields all over the body surface evokes synaptically mediated hyperpolarizing responses in individual mechanoafferent neurons that may represent afferent inhibition. Hyperpolarizing responses lasting many seconds can be produced by brief cutaneous stimuli. The mechanoafferent neurons innervating the tail region make strong monosynaptic connections to tail motor neurons in the ipsilateral pedal ganglion, and through these connections this subpopulation of the VC neurons appears to make a substantial contribution to the short-latency tail-withdrawal reflex. In addition, the combined excitatory receptive fields of these mechanoafferents match the excitatory receptive field of the tail-withdrawal reflex. Mechanoafferent neurons in the VC cluster that have receptive fields on other parts of the body (outside the excitatory receptive field of the tail-withdrawal reflex) have not been observed to make monosynaptic connections to the tail motor neurons. The neurons innervating the tail are reliably found in a discrete region within the larger VC cluster. In addition to this gross somatotopic organization, there is evidence of a finer level of somatotopic organization between the position of the excitatory receptive field on the tail and the position of the cell soma in the tail subcluster.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗