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PubMedDate not supplied

The splitting of sperm heads from tails in eight mammalian species and the measurement of their sizes.

Ejaculated spermatozoa from man, the Euopean wild boar and the bull, and spermatozoa from the cauda epididymes of the rabbit, rat, mouse, hamster and Guinea pig were treated with a sonic bath, a sonic probe, trypsin with and without prior treatment with a sulphhydryl reagent, pronase and alkalis. The fragments produced were counted and sized in an accurately calibrated Coulter Counter, Model ZB Industrial, before and after Zaponin treatment to lyse accompanying debris and the peripheral cytoplasm. Head and tail fractions were separated on sucrose gradients. Each species required different conditions for cleavage or fragmentation. Rabbit and bull spermatozoa were cleaved by the ultrasonic bath exactly into heads and tails, producing twice the number of particles with two peaks in the size distribution curves butith some 60% loss of total sperm volume which became the soluble fraction. The ultrasonic probe, and for the bull, pronase, produced the same cleavage but these more drastic treatments dissolved a considerable portion of the tail fraction. Rodent spermatozoa, especially the rat, were cleaved perfectly into heads and tails by mild trypsin treatment. All the nonrodent spermatozoa were resistent to trypsin cleavage, although prior treatment with a sulphhydryl reagent caused swelling and subsequent trypsin action caused digestion into miscellaneous pieces. Spermatozoa from the boar and from man could not be cleaved by any of the procedures. The sonic probe produced fragmentation with progressive dissolution of the tail fragments and a single peak in the size distribution curve corresponding to small stripped heads. The soluble fraction always constituted a large proportion of the original whole spermatozoa.

Animals↗
PubMed1996

Oximetry for amniotic fluid embolism detection in mini-pigs: tail or snout?

The continuous, non-invasive real-time monitoring of arterial oxygenation (pulse oximetry) has become a standard of care in both human and veterinary medicine. It allows reliable, simple and inexpensive assessment of the arterial oxygenation status. In pigs, commonly used sites for oximetry-probe placement are the ear, snout or tongue, while more recently the 'pig-tail oximetry' has been suggested. In a study regarding the coagulation system during amniotic fluid embolism (AFE) in mini-pigs, we compared tail and snout for oximetry-probe placement and compared them with the 'gold standard': blood-gas analysis (BGA). In both the AFE group and the control group, the tail measurements were slightly lower and the snout measurements were slightly higher than the BGA results. In the experimental model used, both tail and snout measurements were able to detect a temporary desaturation immediately after amniotic fluid embolism (AFE). Blood-gas analysis (BGA) performed on blood drawn from a large artery missed the event. Clinically, there is no significant difference between snout and tail as oximetry-probe placement sites: both are reliable oximetry sites in mini-pigs.

Animals↗
PubMed1992

Effects of systemic non-steroidal anti-inflammatory drugs on nociception during tail ischaemia and on reperfusion hyperalgesia in rats.

1. We have investigated the effects of five non-steroidal anti-inflammatory drugs (NSAIDs) on nociception during ischaemia and on reperfusion hyperalgesia in rats. 2. We induced tail ischaemia in conscious rats by applying a tourniquet at the base of the tail until the rats exhibited co-ordinated escape behaviour when we released the tourniquet. 3. We assessed hyperalgesia by measuring the tail flick latency following tail immersion in water at 49 degrees C, before applying and immediately after releasing the tourniquet, and then at 30 min intervals for 2 h. 4. Intraperitoneal injection of NSAIDs prior to applying the tourniquet had no effect on the co-ordinated escape behaviour during ischaemia, nor on tail flick latency in the absence of prior ischaemia. However all the drugs attenuated reperfusion hyperalgesia in a log dose-dependent manner. Doses required to abolish hyperalgesia, were indomethacin 5 mg kg-1, diclofenac sodium 42 mg kg-1, ibuprofen 54 mg kg-1, dipyrone 168 mg kg-1 and paracetamol 170 mg kg-1. 5. We conclude that the mechanisms underlying nociception during ischaemia are not the same as those underlying reperfusion hyperalgesia. Moreover our procedure provides a rapid and more humane method for measuring the antinociceptive potency of NSAIDs.

Animals↗
PubMed1989

Preliminary evidence for pineal-mediated extraretinal photoreception in relation to tail regeneration in the Gekkonid lizard, Hemidactylus flaviviridis.

The tail of the Gekkonid lizard Hemidactylus flaviviridis was autotomized and the animals were subjected to eight different photoperiodic schedules during the process of tail regeneration. Our previous observation had shown that long-day photoperiods stimulate the regeneration process, whereas short-day photoperiods depress it. Furthermore, it has also been demonstrated that the lateral eyes, or retinae, do not participate in photoperiodically significant photoreception in H. flaviviridis, as blinded Hemidactylus regenerated their autotomized tails like their sighted counterparts exposed to similar experimental photoregimes. In a further attempt to localize the site(s) of photoreception in these animals, one group of lizards had their heads painted with a mixture of Indian ink and Nile blue sulphate (II-NBS) [NL (HP)] in order to prevent light from penetrating to the pineal gland, and another group had their pineal glands surgically removed (pinealectomy, Px); the regenerative potentials were compared with their normal (NL) counterparts. Our results showed that the initiation and onset of regeneration, the daily growth rate, the total new growth (regenerate) produced at the end of regeneration and the total percentage replacement of the lost (autotomized) tails were significantly retarded in Px and NL (HP) animals, compared with the NL (unoperated and nonpainted) ones. Since pinealectomy as well as light deprivation to the pineal abolished the stimulatory influence of long-length photoperiods, the pineal gland is discussed here as a major transmitter of photic stimulus in lacertilian tail regeneration. It is presumed that in the lizard, as in mammals and some birds, the pineal gland acts by way of the neuroendocrine complex and/or the hypothalamohypophyseal axis.

Animals↗
PubMed1982

Are isolated femoral resistance vessels or tail arteries good models for the hindquarter vasculature of spontaneously hypertensive rats?

We have investigated the extent to which the properties of small arteries from the hindquarters of spontaneously hypertensive rats (SHRs) are consistent with the characteristics of perfused SHR hindquarter preparations (for which the relaxed vascular resistance, the reactivity and the sensitivity are reported to be increased). We have therefore compared the in vitro morphological and pharmacological properties of a femoral resistance vessel (i.d. ca 200 microns) and of the tail artery (i.d. ca 600 microns) from SHRs with those from control Wistar-Kyoto rats (WKYs). When relaxed, for any given wall tension, the internal circumference of the SHR resistance vessels was reduced, but that of the SHR tail artery was normal. When activated with 10 microM noradrenaline, the SHR resistance vessels had an increased calcium sensitivity, but the calcium sensitivity of the SHR tail arteries was normal. However, the maximum response of both types of SHR vessels was such that the vessels would have been able to contract against increased transmural pressure. The noradrenaline sensitivity of the SHR resistance vessels was normal but the SHR tail arteries had a decreased sensitivity. The results suggest that the femoral resistance vessel is in general a better model for the hindquarter vasculature than the tail artery.

Animals↗
PubMed1977

The effects of diarrhoea, tail length and sex on the incidence of breech strike in modified mulesed Merino sheep.

Merino sheep were treated with purgative to induce scouring and the effects of tail length and sex on the incidence and origin of breech strike were examined. In sheep treated with the modified Mules operation, those with tails docked very short were strongly predisposed to tail strike, and to a lesser extent, crutch strike. Tails docked level with, or just below, the tip of the vulva in ewes, and at the equivalent length in wethers, were struck far less frequently. Within each tail length group, wethers tended to be more susceptible than ewes. L. cuprina was the principal species of fly involved in strikes, although the presence of L. sericata and C. augur was conspicuous.

Animals↗
PubMed1996

Tail docking in dogs: a sample of attitudes of veterinarians and dog breeders in Queensland.

One hundred veterinarians and 100 breeders of traditionally docked dogs from Queensland were surveyed by telephone to determine their attitudes towards tail docking. Eighty-four percent of the breeders surveyed were in favour of docking, whereas 83% of veterinarians were opposed to the practice. Most pups were docked between 1 and 3 days of age. All veterinarians surgically amputated the tail, whereas 16% of breeders applied rubber bands to the tail. Seventy-six percent of the veterinarians, but only 18% of the breeders believed that docking caused significant to severe pain. No veterinarians, but 25% of the dog breeders believed that docking was painless. Although recent changes to the Queensland Canine Control Council's rulings allow dogs with intact tails to be shown in traditionally docked classes, the requirement of breed standard was cited as the major reason for tail docking by both breeders and veterinarians.

Animals↗
PubMed1983

Roles of extrajunctional receptors in the response of guinea-pig mesenteric and rat tail arteries to adrenergic nerves.

Studies of the electrical response of isolated guinea-pig mesenteric and rat tail arteries to perivascular nerve stimulation were made by micro-electrodes inserted from the outer surface of the vessels. Membrane potential of both arteries was -68 to -69 mV and usually stable, though with occasional miniature excitatory junction potentials (m.e.j.p.s). Perivascular nerve stimulation produced excitatory junction potentials (e.j.p.s) which usually increased in size with repetitive stimulation, particularly in the mesenteric artery, but rarely triggered a spike or other regenerative response. Phentolamine and yohimbine in low concentrations increased the size of the e.j.p.s in both arteries, and increased the mechanical response of the mesenteric artery, probably by blocking prejunctional alpha 2 receptors which depress release of noradrenaline by the nerves; they reduced the mechanical response of the tail artery, probably by blocking alpha 2 receptors of the smooth muscle. Prazosin in low concentration had no effect on the e.j.p.s but inhibited contraction in both arteries, probably by blocking alpha 1 receptors of the smooth muscle. In the tail artery, but not the mesenteric artery, e.j.p.s produced by repetitive perivascular nerve stimulation were followed by a slow depolarization reaching a maximum at about 20 s and then decaying over 1-3 min; it did not reach the threshold for contraction, assessed by K depolarization. Yohimbine reduced the size and duration of the slow depolarization. High concentrations of noradrenaline (10(-5) M) caused depolarization and contraction of the mesenteric artery, both of which were blocked by prazosin and little affected by yohimbine. In the tail artery, yohimbine did but prazosin did not block the depolarization produced by any concentration of noradrenaline, although yohimbine was almost as effective as prazosin in blocking the contraction produced by low concentrations of noradrenaline. Extrajunctional adrenoceptors in the mesenteric artery therefore included high sensitivity types of alpha 1 receptor, and in the tail artery high sensitivity types of alpha 1 and alpha 2 receptor. Some of the extrajunctional receptors, as well as the junctional receptors responsible for e.j.p.s in both arteries, produced depolarization. Most of the contraction induced by either nerves or exogenous noradrenaline was produced by the extrajunctional receptors, and was not dependent on the depolarization which some of these receptors induced.

Action Potentials↗
PubMed2005

Dependence of mechanical behavior of the murine tail disc on regional material properties: a parametric finite element study.

In vivo rodent tail models are becoming more widely used for exploring the role of mechanical loading on the initiation and progression of intervertebral disc degeneration. Historically, finite element models (FEMs) have been useful for predicting disc mechanics in humans. However, differences in geometry and tissue properties may limit the predictive utility of these models for rodent discs. Clearly, models that are specific for rodent tail discs and accurately simulate the disc's transient mechanical behavior would serve as important tools for clarifying disc mechanics in these animal models. An FEM was developed based on the structure, geometry, and scale of the mouse tail disc. Importantly, two sources of time-dependent mechanical behavior were incorporated: viscoelasticity of the matrix, and fluid permeation. In addition, a novel strain-dependent swelling pressure was implemented through the introduction of a dilatational stress in nuclear elements. The model was then validated against data from quasi-static tension-compression and compressive creep experiments performed previously using mouse tail discs. Finally, sensitivity analyses were performed in which material parameters of each disc subregion were individually varied. During disc compression, matrix consolidation was observed to occur preferentially at the periphery of the nucleus pulposus. Sensitivity analyses revealed that disc mechanics was greatly influenced by changes in nucleus pulposus material properties, but rather insensitive to variations in any of the endplate properties. Moreover, three key features of the model-nuclear swelling pressure, lamellar collagen viscoelasticity, and interstitial fluid permeation-were found to be critical for accurate simulation of disc mechanics. In particular, collagen viscoelasticity dominated the transient behavior of the disc during the initial 2200 s of creep loading, while fluid permeation governed disc deformation thereafter. The FEM developed in this study exhibited excellent agreement with transient creep behavior of intact mouse tail motion segments. Notably, the model was able to produce spatial variations in nucleus pulposus matrix consolidation that are consistent with previous observations in nuclear cell morphology made in mouse discs using confocal microscopy. Results of this study emphasize the need for including nucleus swelling pressure, collagen viscoelasticity, and fluid permeation when simulating transient changes in matrix and fluid stress/strain. Sensitivity analyses suggest that further characterization of nucleus pulposus material properties should be pursued, due to its significance in steady-state and transient disc mechanical response.

Animals↗
PubMed1981

Different command neurons select different outputs from a shared premotor interneuron of crayfish tail-flip circuitry.

In the crayfish a bilateral pair of interneurons (the 13's) are involved in the generation of two types of tail-flip escape responses, one mediated by giant neurons and the other by nongiant circuitry. The 13's make a variety of output connections with the motoneurons and with other interneurons involved in tail flipping. The motoneuronal outputs include strong synapses on telson flexor motoneurons, whose activity during tail flips mediated by lateral giant fibers would be maladaptive. The lateral giants always drive the 13's, but also drive inhibitory neurons that prevent the undesirable outputs of the 13's while permitting their adaptive outputs to be expressed. It is often adaptive for tail flips initiated by nongiant circuitry to utilize the telson flexor muscles that 13 strongly excites. During such tail flips 13 is often fired, and this firing is important in driving the telson flexors.

Action Potentials↗
PubMed1996

Characterization of the helper proteins for the assembly of tail fibers of coliphages T4 and lambda.

Assembly of tail fibers of coliphage T4 requires the action of helper proteins. In the absence of one of these, protein 38 (p38), p37, constituting the distal part of the long tail fiber, fails to oligomerize. In the absence of the other, p57, p34 (another component of the long tail fiber), p37, and p12 (the subunit of the short tail fiber) remain unassembled. p38 can be replaced by the Tfa (tail fiber assembly) protein (pTfa) of phage lambda, which has the advantage of remaining soluble even when produced in massive amounts. The mechanisms of action of the helpers are unknown. As a first step towards elucidation of these mechanisms, p57 and pTfa have been purified to homogeneity and have been crystallized. The identity of gene 57 (g57), not known with certainty previously, has been established. The 79-residue protein p57 represents a very exotic polypeptide. It is oligomeric and acidic (an excess of nine negative charges). It does not contain Phe, Trp, Tyr, His, Pro, and Cys. Only 25 N-terminal residues were still able to complement a g57 amber mutant, although with a reduced efficiency. In cells overproducing the protein, it assumed a quasi-crystalline structure in the form of highly ordered fibers. They traversed the cells longitudinally (and thus blocked cell division) with a diameter approaching that of the cell and with a hexagonal appearance. The 194-residue pTfa is also acidic (an excess of 13 negative charges) and is likely to be dimeric.

Bacteriophage T4↗
PubMed2002

Bacteriophage SP6 is closely related to phages K1-5, K5, and K1E but encodes a tail protein very similar to that of the distantly related P22.

The lytic salmonella phage SP6 encodes a tail protein with a high degree of sequence similarity to the tail protein of the biologically unrelated lysogenic salmonella phage P22. The SP6 tail gene is flanked by an upstream region that contains a promoter and a downstream region that contains a putative Rho-independent transcription terminator, giving it a cassette or modular structure almost identical to the structure of the tail genes of coliphages K1E, K5, and K1-5. It now appears that SP6, K1-5, K5, and K1E are very closely related but have different tail fiber proteins, giving them different host specificities.

Amino Acid Sequence↗
PubMed2001

Bacteriophage K1-5 encodes two different tail fiber proteins, allowing it to infect and replicate on both K1 and K5 strains of Escherichia coli.

A virulent double-stranded DNA bacteriophage, Phi K1-5, has been isolated and found to be capable of infecting Escherichia coli strains that possess either the K1 or the K5 polysaccharide capsule. Electron micrographs show that the virion consists of a small icosohedral head with short tail spikes, similar to members of the Podoviridae family. DNA sequence analysis of the region encoding the tail fiber protein showed two open reading frames encoding previously characterized hydrolytic phage tail fiber proteins. The first is the K5 lyase protein gene of Phi K5, which allows this phage to specifically infect K5 E. coli strains. A second open reading frame encodes a protein almost identical in amino acid sequence to the N-acetylneuraminidase (endosialidase) protein of Phi K1E, which allows this phage to specifically infect K1 strains of E. coli. We provide experimental evidence that mature phage particles contain both tail fiber proteins, and mutational analysis indicates that each protein can be independently inactivated. A comparison of the tail gene regions of Phi K5, Phi K1E, and Phi K1-5 shows that the genes are arranged in a modular or cassette configuration and suggests that this family of phages can broaden host range by horizontal gene transfer.

Antigens, Bacterial↗
PubMed1984

Tail painting technique as an aid to oestrus detection in cattle.

The value of heat detection by tail painting was assessed by simultaneous visual observation and regular plasma progesterone assay in grazing animals; 88.1 per cent of all heats were accompanied by a positive tail paint record and 30.1 per cent of positive tail paint records occurred in dioestrous animals. Conception rates to the first insemination were 57.6 per cent and 57.9 per cent for heifers and cows, respectively. Of seven animals which showed behavioural oestrus but had intact tail paint, three conceived following insemination. These results suggest that tail paint may be a useful aid in heat detection.

Animals↗
PubMed2000

Three different vasoactive responses of rat tail artery to nicotine.

The vasoactive effects of nicotine on isolated rat tail artery tissues were studied. Nicotine transiently contracted rat tail artery tissues (EC50, 55.6 +/- 2 microM) in an extracellular Ca2+ dependent and endothelium-independent fashion. The blockade of alpha1-adrenoceptors, but not alpha2-adrenoceptors or P2X purinoceptors, inhibited the nicotine-induced contraction by 38 +/- 7% (p < 0.05). Nicotine (1 mM) depolarized membrane by 13 +/- 3 mV, but did not affect L-type Ca2+ channel currents, of the isolated rat tail artery smooth muscle cells. The phenylephrine-precontracted tail artery tissues were relaxed by nicotine (EC50, 0.90 +/- 0.31 mM), which was significantly inhibited after the blockade of nicotinic receptors. Simultaneous removal of phenylephrine and nicotine, after a complete relaxation of the phenylephrine-precontracted tail artery strips was achieved by nicotine at accumulated concentrations (> or =10 mM), triggered a Ca2+-dependent rebound long-lasting vasoconstriction (n = 20). This rebound contraction was abolished in the absence of calcium or in the presence of tetracaine in the bath solution. Pretreatment of vascular tissues with a nicotinic receptor antagonist did not affect the nicotine-induced vasoconstriction or nicotine withdrawal induced rebound contraction. The elucidation of the triphasic vascular effects of nicotine and the underlying mechanisms is important for a better understanding of the complex vascular actions of nicotine.

Animals↗
PubMed1984

Alterations in aortic and tail artery reactivity to agonists after streptozotocin treatment.

In the present study, responses to various agonists in thoracic aorta and tail artery strips, obtained from 4-week streptozotocin (STZ)-treated rats and age-matched controls, were studied. Responses in aorta obtained from diabetic animals to the alpha-agonists, norepinephrine (NE), and methoxamine (MOX), to calcium (Ca2+) and potassium (K+) were found to be depressed relative to control tissue. Responses in tail artery however, were found to be different. While responses to K+ were decreased and to Ca2+ unchanged, tail artery strips obtained from diabetic animals were found to be supersensitive to both alpha-agonists relative to control tissue. Another observed difference between the two tissues was in their catecholamine content. While induction of diabetes did not alter catecholamine levels in the aorta, a significant decrease was produced in the tail artery, relative to control tissue levels. Our results indicate that inherent differences (such as the degree of innervation) may contribute to the differential responses observed in the two tissues studied. They further suggest the possible involvement of alterations in calcium utilization in aorta and the development of postjunctional supersensitivity in tail artery obtained from STZ-treated animals.

Animals↗
PubMed1985

Mode of neural control mediating rat tail vasodilation during heating.

The purpose of this investigation was to delineate the mode of efferent neural control mediating rat tail vasodilation during body heating. Tail blood flow (venous occlusion plethysmography), tail skin temperature over the ventral vascular bundle, and arterial pressure were measured in Sprague-Dawley rats anesthetized with pentobarbital sodium (45 mg/kg). Three protocols were followed: anesthesia of the lumbar sympathetic chain, bilateral lumbar sympathectomy, and sympathetic nerve stimulation during varying degrees of alpha-adrenergic receptor blockade. Mean tail blood flow and tail vascular conductance (TVC) during body heating were 40.3 +/- 8.7 ml X 100 ml-1 X min-1 and 39.2 +/- 9.2 ml X 100 ml-1 X min-1 X 100 mmHg-1, respectively. Interruption of sympathetic nerve activity by sympathetic nerve anesthetization or sympathectomy during heat stress caused a nonsignificant increase in TVC to 112.7 +/- 1.8 and 121.12 +/- 6.3%, respectively, of the values achieved with body heating. Sympathectomy performed in normothermic animals that had recovered from prior heating caused an increase in TVC to 128.4 +/- 14.0% of the levels achieved during the previous heating period. In addition, sympathetic nerve stimulation after complete alpha-adrenergic receptor blockade failed to produce a vasodilation [control TVC = 10.2 +/- 3.9 vs. TVC during nerve stimulation = 10.4 +/- 3.9 (P greater than 0.05)]. It is concluded that the increase in TVC during body heating occurs solely via a reduction in vasoconstrictor nerve activity.

Animals↗
PubMed1989

Baroreflex control of the rat tail circulation in normothermia and hyperthermia.

The role of thermoregulatory background in the baroreceptor reflex control of the tail circulation was investigated 1) in anesthetized rats with a constant flow technique and 2) in conscious rats by measuring tail blood flow (venous occlusion plethysmography). In series I, during normothermia, systemic intravenous phenylephrine infusion increased mean arterial pressure (MAP) by 61.0 +/- 3.6 mmHg and induced a reflex decrease in tail perfusion pressure (TPP) from 105.0 +/- 6.3 to 84.2 +/- 4.4 mmHg (P less than 0.005). Hyperthermia decreased TPP to 66.5 +/- 5.1 mmHg (P less than 0.001) and abolished the TPP response to increased MAP (P greater than 0.05). Increases in MAP via systemic infusion of whole blood caused reductions in TPP during normothermia but failed to reduce TPP further during hyperthermia. Graded decreases in MAP during both normothermia and hyperthermia caused tail vasoconstriction. The increase in TPP was greater (P less than 0.025) during hyperthermia. In series II, conscious animals showed similar responses to hemorrhage. Graded decreases in MAP produced graded decreases in tail vascular conductance (TVC, ml.100 ml-1.min-1.100 mmHg-1). The slope of the TVC-MAP relationship averaged 0.011 +/- 0.003 TVC U/mmHg during normothermia and was markedly steeper (P less than 0.01) during hyperthermia (1.99 +/- 0.39 TVC U/mmHg). Thus the participation of the cutaneous vasculature of the rat in baroreceptor reflexes depends on thermal status, probably through the level of background sympathetic vasoconstrictor nerve activity.

Animals↗