Do E-health interventions improve physical activity in young people: a systematic review.

OBJECTIVES: This study aims to review the current literature to assess the effectiveness of E-health interventions in increasing physical activity (PA) in young people. STUDY DESIGN: This study is a systematic review of the literature. METHODS: A search of the literature databases Embase, MEDLINE and the Cochrane Library using key words 'Adolescents'; 'Young people'; 'Students'; 'Young Adults'; 'Teenagers'; 'E-health'; 'Internet-based'; 'Web-based'; 'Exercise'; 'Activity'; 'Sport' and 'Intervention' yielded 10 articles which fit the criteria for inclusion. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol was used, and papers were excluded if they were disease focused, not specific to young people (those attending school, college or university) or did not measure PA as an outcome. RESULTS: Eight of the 10 studies had significant increases in PA as a result of an E-health intervention. Studies that did not use a theoretical principle to underpin their intervention did not achieve successful results. Interventions based on social cognitive theory were very successful in achieving an increase in PA. The theory of planned behaviour had mixed results, with studies having contrasting results. Specific, measurable, achievable, relevant and time-bound (SMART) goal principle was not effective in increasing PA but had positive findings in supplementary outcomes such as goal setting. CONCLUSIONS: E-health interventions are a very successful way to increase PA. More research is required to look at what theoretical principles are best to underpin interventions and also to assess the length of intervention required for optimal results after intervention. Ideas surrounding implementation and the mediums used require more studies to evidence base these interventions for schools, colleges and university via intracurriculum or extracurriculum.

Metallothionein as a clonable tag for protein localization by electron microscopy of cells.

A benign, clonable tag for the localization of proteins by electron microscopy of cells would be valuable, especially if it provided labelling with high signal-to-noise ratio and good spatial resolution. Here we explore the use of metallothionein as such a localization marker. We have achieved good success with desmin labelled in vitro and with a component of the yeast spindle pole body labelled in cells. Heavy metals added after fixation and embedding or during the process of freeze-substitution fixation provide readily visible signals with no concern that the heavy atoms are affecting the behaviour of the protein in its physiological environment. However, our methods did not work with protein components of the nuclear pore complex, suggesting that this approach is not yet universally applicable. We provide a full description of our optimal labelling conditions and other conditions tried, hoping that our work will allow others to label their own proteins of interest and/or improve on the methods we have defined.

Effects of caffeine on session ratings of perceived exertion.

This study examined effects of caffeine on session ratings of perceived exertion (RPE) following 30 min constant-load cycling. Individuals (n = 15) of varying aerobic fitness completed a [Formula: see text] max trial and two 30 min cycling bouts (double-blind, counterbalanced) following ingestion of 6 mL/kg of caffeine or matched placebo. RPE overall, legs and breathing were estimated every 5 min and session RPE was estimated 30 min post-exercise using the OMNI pictorial scale. Session RPE for caffeine and placebo trails were compared using paired t test. Between-trial comparisons of HR, RPE overall, RPE legs and RPE breathing were analyzed using an independent 2 (trial) × 6 (time point) repeated measures analysis of variance (ANOVA) for each dependent variable. Caffeine resulted in a significantly lower session RPE (p < 0.05) for caffeine (6.1 ± 2.2) versus placebo (6.8 ± 2.1). Acute perceptual responses were significantly lower for caffeine for RPE overall (15, 20, 25, and 30 min), RPE breathing (15, 20, 25, and 30 min) and RPE legs (20 and 30 min). Survey responses post-exercise revealed greater feelings of nervousness, tremors, restlessness and stomach distress following caffeine versus placebo. Blunted acute RPE and survey responses suggest participants responded to caffeine ingestion. Caffeine decreased acute RPE during exercise which could partially account for lower session RPE responses. However, decreased session RPE could also reveal a latent analgesic affect of caffeine extending into recovery. Extending the understanding of session RPE could benefit coaches in avoiding overtraining when adjusting training programs.

Different assemblies of the DAM1 complex follow shortening microtubules by distinct mechanisms.

Mitotic chromosomes segregate at the ends of shortening spindle microtubules (MTs). In budding yeast, the Dam1 multiprotein complex supports this dynamic attachment, thereby contributing to accurate chromosome segregation. Purified Dam1 will track the end of a depolymerizing MT and can couple it to microbead transport in vitro. The processivity of such motions has been thought to depend on rings that the Dam1 complex can form around MTs, but the possibility that alternative coupling geometries contribute to these motilities has not been considered. Here, we demonstrate that both rings and nonencircling Dam1 oligomers can track MT ends and enable processive cargo movement in vitro. The coupling properties of these two assemblies are, however, quite different, so each may make a distinct contribution to chromosome motility.

Estimation of phase in EEG rhythms for real-time applications.

OBJECTIVE: Estimating the ongoing phase of oscillations in electroencephalography (EEG) recordings is an important aspect of understanding brain function, as well as for the development of phase-dependent closed-loop real-time systems that deliver stimuli. Such stimuli may take the form of direct brain stimulation (for example transcranial magnetic stimulation), or sensory stimuli (for example presentation of an auditory stimulus). We identify two linked problems related to estimating the phase of EEG rhythms with a specific focus on the alpha-band: 1) when the signal after a specific stimulus is unknown (real-time case), or 2) when it is corrupted by the presence of the stimulus itself (offline analysis). We propose methods to estimate the phase at the presentation time of these stimuli. APPROACH: Machine learning methods are used to learn the causal mapping from an unprocessed EEG recording to a phase estimate generated with a non-causal signal processing chain. This mapping is then used to predict the phase causally where non-causal methods are inappropriate. MAIN RESULTS: We demonstrate the ability of these machine learning methods to estimate instantaneous phase from an EEG signal subjected to very minor pre-processing with higher accuracy than commonly used signal-processing methods. SIGNIFICANCE: Neural oscillations have been implicated in a wide variety of sensory, cognitive and motor functions. The instantaneous phase of these rhythms may reflect specific processes of computation which can be acted upon if they can be estimated with sufficient accuracy. Such brain-state dependent paradigms are of increasing medical and scientific interest.

Bridges between microtubules.

Bridges between microtubules have been studied with the electron microscope in the axostyle of Saccinobaculus and in various tubule systems of chicken testis, including the helix of tubules surrounding the elongating spermatid nucleus and the flagellum of the sperm tail. In addition to the previously described periodic bridges, evidence is presented that nonperiodic bridges exist between certain tubules. An analysis of axial spacing between adjacent nonperiodic bridges suggests that these structures are attached to periodic binding sites on the microtubule wall, but that not all the binding sites are filled. The bridges appear nonperiodic as a result of random occupancy of some fraction of the periodic sites. The distribution of these binding sites is related to the substructure of the microtubule wall as seen with negative staining and optical diffraction.

The axostyle of Saccinobaculus. II. Motion of the microtubule bundle and a structural comparison of straight and bent axostyles.

Undulations of the flagellate Saccinobaculus result from motility in its axostyle, a bundle consisting of thousands of cross-bridged microtubules. In its resting state, the axostyle is a helix of large pitch and slowly varying radius. The active state as seen by light microscopy involves first a bending of the anterior end of the axostyle to a radius of about 8 microm with a circular arc ranging from 60 degrees to 180 degrees , and then the propagation of this bend without damping to the posterior end of the organism at speeds up to 100 microm/s. The cross section of an unbent axostyle is crescent shaped. This crescent flattens as the bend arrives and reappears as the bend passes by. Intertubule bridges impart to the axostyle tubules an axial periodicity of about 150 A which can serve as a marker for the investigation of tubule sliding or contraction associated with bend formation. Optical diffraction measurements on electron micrographs of the bend demonstrate that the axostyle tubules slide over one another and that the tubules on the inside of a bend usually contract, sometimes by as much as 25%. Possible relationships between the contraction and sliding of the tubules are discussed.

Tubulin hooks as probes for microtubule polarity: an analysis of the method and an evaluation of data on microtubule polarity in the mitotic spindle.

The structural polarity of cellular microtubules can be visualized in situ by lysing cells in special buffers containing tubulin. Under these conditions, the tubulin polymerizes to form curved sheets which attach to the walls of the endogenous microtubules. When such decorated microtubules are cut in cross section and viewed in the electron microscope, they appear to bear hooks curving clockwise or counter-clockwise. The direction of hook curvature is defined by the orientation of the decorated microtubule and thus serves as a probe for microtubule polarity. In this paper we describe a way to analyze the relative frequencies of hooks of different curvatures so as to measure the fidelity of the relation between hook curvature and microtubule polarity. The assumptions of the method are tested and found to be valid to a reasonable accuracy. The correlation between hook curvature and microtubule orientation is shown to be at least 0.98 for the spindles of PtK cells and Haemanthus endosperm at all stages of division and at all places in the spindle. The correlation is shown to be valid for each hook that forms, so the polarity of those microtubules that bear multiple hooks is specified with even better certainty than 0.98. This property of hook decoration is used to reinvestigate the possibility that some of the microtubules of the kinetochore fiber might be oriented with their plus ends distal to the kinetochore (opposite to the direction previously shown to predominate). Close analysis fails to identify such oppositely oriented microtubules. The scoring of tubules bearing multiple hooks also shows that individual interzone fibers at anaphase are constructed from clusters of antiparallel microtubules. The method for estimating the correlation between hook decoration and microtubule polarity is shown to be applicable to many structures and circumstances, but we find that the hook decoration assay for microtubule polarity is not uniformly accurate. We suggest that future studies using hook decorations should employ the method of data analysis presented here to assess the accuracy of the results obtained.

Polarity of midbody and phragmoplast microtubules.

A newly discovered method (Heidemann and McIntosh, 1980, Nature [Lond.] 286:517) for displaying the molecular polarity of microtubules (MTs) has been slightly modified and applied to the midbodies of cultured mammalian cells and the phragmoplasts of Haemanthus endosperm. The method involves the decoration of preexisting MTs in lysed cells with curved ribbons of tubulin protofilaments; the direction of curvature of these C-shaped appendages as seen in cross section reflects the intrinsic polarity of the MTs. In travsverse sections of midbodies from HeLa and PtK cells, we find that essentially all the MTs in a given region of the structures have the same direction of hook curvature, and hence the same polarity. The midbody MTs that lie on one side of the spindle equator show the opposite polarity from those on the other side, indicating that the midbody is constructed from two families of antiparallel MTs. Midbody MTs are arranged with their fast-growing ends overlapping at the spindle equator, consistent with the hypothesis that the midbody is formed by the interdigitation of aster MTs. The polarities of the MTs from the phragmoplast of endosperm cells are the same as those found in the mammalian midbody. Our results eliminate one model for mitosis, but are consistent with others. The systematic and reproducible polarities observed favor the concept that MT polarity is an important factor in the formation and/or the function of these two mitotic structures.

Structural polarity of kinetochore microtubules in PtK1 cells.

The polarity of kinetochore microtubules (MTs) has been studied in lysed PtK1 cells by polymerizing hook-shaped sheets of neurotubulin onto walls of preexisting cellular MTs in a fashion that reveals their structural polarity. Three different approaches are presented here: (a) we have screened the polarity of all MTs in a given spindle cross section taken from the region between the kinetochores and the poles, (b) we have determined the polarity of kinetochore MTs are more stable to cold-treated spindles; this approach takes advantage of the fact that kinetochore MTs are more stable to cold treatment than other spindle MTs; and (c) we have tracked bundles of kinetochore MTs from the vicinity of the pole to the outer layer of the kinetochore in cold-treated cells. In an anaphase cell, 90-95% of all MTs in an area between the kinetochores and the poles are of uniform polarity with their plus ends (i.e., fast growing ends) distal to the pole. In cold-treated cells, all bundles of kinetochore MTs show the same polarity; the plus ends of the MTs are located at the kinetochores. We therefore conclude that kinetochore MTs in both metaphase and anaphase cells have the same polarity as the aster MTs in each half-spindle. These results can be interpreted in two ways: (a) virtually all MTs are initiated at the spindle poles and some of the are "captured" by matured kinetochores using an as yet unknown mechanism to bind the plus ends of existing MTs; (b) the growth of kinetochore MTs is initiated at the kinetochore in such a way that the fast growing MT end is proximal to the kinetochore. Our data are inconsistent with previous kinetochore MT polarity determinations based on growth rate measurements in vitro. These studies used drug-treated cells from which chromosomes were isolated to serve as seeds for initiation of neurotubule polymerization. It is possible that under these conditions kinetochores will initiate MTs with a polarity opposite to the one described here.

Fluorescent microtubules break up under illumination.

We have synthesized three new fluorescent analogues of tubulin, using fluorescein or rhodamine groups attached to N-hydroxy-succinimidyl esters, and have partially characterized the properties of these analogues. We have also further characterized the tubulin derivatized with dichlorotriazinyl-aminofluorescein that has previously been used in this and other laboratories. Our results show that all four analogues assemble into microtubules which break up when exposed to light of the wavelengths that excite fluorescence. This sensitivity places severe constraints on the use of these analogues in studies of microtubule dynamics.

Microtubules in the spermatids of the domestic fowl.

Spermiogenesis in chicken has been examined in order to see whether the radical changes observed in cell shape can be related to the presence of cytoplasmic microtubules. A highly ordered array of tubules has been found which surrounds the nucleus as it elongates from a sphere to a slender cylinder. The structure of the array has been determined by following the tubules through 12-14 adjacent serial sections, and it is a left-handed double helix. Faint cross-bridges connect consecutive turns of the two helices. After the change in nuclear shape is complete, the helical system of microtubules disappears and is replaced by a set of almost straight tubules which run parallel to the long axis of the nucleus. These tubules remain while the spermatid nucleus condenses isotropically to its final size. We suggest that the helix is the agent which effects nuclear elongation and that the subsequent system of paraxial tubules determines the curvature of the final sperm head. Evidence for these suggestions is found in the form of spermatids which have failed to develop properly. In an appendix we consider the kinematics of single and multiple helix systems and discuss the revelance of these models to the morphogenesis of chicken spermatids.

Polarity of spindle microtubules in Haemanthus endosperm.

Structural polarities of mitotic spindle microtubules in the plant Haemanthus katherinae have been studied by lysing endosperm cells in solutions of neurotubulin under conditions that will decorate cellular microtubules with curved sheets of tubulin protofilaments. Microtubule polarity was observed at several positions in each cell by cutting serial thin sections perpendicular to the spindle axis. The majority of the microtubules present in a metaphase or anaphase half-spindle are oriented with their fast-growing or "plus" ends distal to the polar area. Near the polar ends of the spindle and up to about halfway between the kinetichores and the poles, the number of microtubules with opposite polarity is low: 8-20% in metaphase and 2-15% in anaphase cells. Direct examination of 10 kinetochore fibers shows that the majority of these microtubules, too, are oriented with their plus ends distal to the poles, as had been previously shown in animal cells. Sections from the region near the spindle equator reveal an increased fraction of microtubules with opposite polarity. Graphs of polarity vs. position along the spindle axis display a smooth transition from microtubules of one orientation near the first pole, through a region containing equal numbers of the two orientations, to a zone near the second pole where the opposite polarity predominates. We conclude that the spindle of endosperm cells is constructed from two sets of microtubules with opposite polarity that interdigitate near the spindle equator. The length of the zone of interdigitation shortens from metaphase through telophase, consistent with a model that states that during anaphase spindle elongation in Haemanthus, the interdigitating sets of microtubules are moved apart. We found no major changes in the distribution of microtubule polarity in the spindle interzone from anaphase to telophase when cells are engaged in phragmoplast formation. Therefore, the initiation and organization of new microtubules, thought to take place during phragmoplast assembly, must occur without significant alteration of the microtubule polarity distribution.

Isolation and initial characterization of the mammalian midbody.

Midbodies were isolated from synchronized cultures of Chinese hamster ovary (CHO) cells and their protein composition was studied by means of SDS PAGE. Gels of the midbodies included alpha and beta tubulins as major bands (approximately 30% of the total protein) and approximately 35 other bands, none of which constituted greater than 3.5% of the total protein. Extraction of the isolated midbodies with Sarkosyl NL-30- solubilized the midbody microtubules but left the central, dense matrix zone of the midbody intact. A protein doublet of approximately 115,000 mol wt was retained preferentially by the particulate fraction containing the matrix zones, indicating it to be a component of the matrix. The 115,000 mol wt doublet was also present in gels of isolated mitotic spindles from CHO cells. The overall protein composition of the isolated spindles was very similar to that of the isolated midbodies.

Interzone microtubule behavior in late anaphase and telophase spindles.

We have studied microtubule behavior in late anaphase and telophase spindles of PtK1 cells, using fluoresceinated tubulin (DTAF-tubulin), microinjection, and laser microbeam photobleaching. We present the results of two novel tests which add to the evidence that DTAF-tubulin closely mimics the behavior of native tubulin in vivo. (a) Microinjected DTAF-tubulin was as effective as injected native tubulin in promoting division of taxol-dependent mitotic mutant cells that had been deprived of taxol. (b) Microinjected colchicine-DTAF-tubulin complex was similar to injected colchicine-native tubulin complex in causing depolymerization of spindles. Immediately after microinjection of DTAF-tubulin into wild-type cells during late anaphase or telophase, fluorescence incorporation by microtubules was seen in chromosomal half-spindles and just behind the chromosomes, but there was no fluorescence incorporation near the middle of the interzone. Over the next few minutes, tubulin fluorescence accumulated at the center of the interzone (the equator), becoming progressively more intense. In other experiments, cells were microinjected with DTAF-tubulin at prophase and allowed to equilibrate for 30 min. Cells that had progressed to late anaphase were then photobleached to reduce the fluorescence in the central portion of the interzone. Over a period of several minutes, the only substantial redistribution of fluorescence was the appearance of a bright area at the equator of the interzone. Both the site of fluorescence incorporation and the photobleaching data suggest that tubulin adds to the elongating spindle interzone near the equator where the plus ends of the interdigitated microtubules are located. In further experiments, several dark lines were photobleached perpendicular to the pole-to-pole axis of fluorescent anaphase-telophase spindles. Time-dependent changes in the spacings between the lines indicated that the two halves of the interzone lying on opposite sides of the spindle equator moved away from one another. This shows that the interdigitated microtubules, which make up most of the interzone, can undergo antiparallel sliding. Our data support a model for anaphase B in which plus end elongation of interdigitated microtubules and antiparallel sliding contribute to chromosome separation.

Microtubule depolymerization promotes particle and chromosome movement in vitro.

We have developed a system for studying the motions of cellular objects attached to depolymerizing microtubules in vitro. Radial arrays of microtubules were grown from lysed and extracted Tetrahymena cells attached to a glass coverslip that formed the top of a light microscope perfusion chamber. A preparation of chromosomes, which also contained vesicles, was then perfused into the chamber and allowed to bind to the microtubule array. The concentration of tubulin was then reduced by perfusing buffer that lacked both tubulin and nucleotide triphosphates, and the resulting microtubule depolymerization was observed by light microscopy. A fraction of the bound objects detached in the flow and washed away, while others stabilized the microtubules to which they were bound. Some of the particles and chromosomes, however, moved in toward the Tetrahymena ghost as their associated microtubules shortened. The mean speeds for particles and chromosomes were 26 +/- 20 and 15 +/- 12 microns/min, respectively. These motions occurred when nucleotide triphosphate levels were very low, as a result of either dilution or by the action of apyrase. Furthermore, the motions were unaffected by 100 microM sodium orthovanadate, suggesting that these forces are not the result of ATP hydrolysis by a minus end-directed mechanoenzyme. We conclude that microtubule depolymerization provided the free energy for the motions observed. All the objects that we studied in detail moved against a stream of buffer flowing at approximately 100 microns/s, so that the force being developed was at least 10(-7) dynes. This force is large enough to contribute to some forms of motility in living cells.

Three-dimensional reconstruction and analysis of mitotic spindles from the yeast, Schizosaccharomyces pombe.

Mitotic spindles of Schizosaccharomyces pombe have been studied by EM, using serial cross sections to reconstruct 12 spindles from cells that were ultrarapidly frozen and fixed by freeze substitution. The resulting distributions of microtubules (MTs) have been analyzed by computer. Short spindles contain two kinds of MTs: continuous ones that run from pole to pole and MTs that originate at one pole and end in the body of the spindle. Among the latter there are three pairs of MT bundles that end on fibrous, darkly staining structures that we interpret as kinetochores. The number of MTs ending at each putative kinetochore ranges from two to four; all kinetochore-associated MTs disappear as the spindle elongates from 3-6 microns. At this and greater spindle lengths, there are no continuous MTs, only polar MTs that interdigitate at the spindle midzone, but the spindle continues to elongate. An analysis of the density of neighboring MTs at the midzone of long spindles shows that their most common spacing is approximately 40 nm, center to center, and that there is a preferred angular separation of 90 degrees. Only hints of such square-packing are found at the midzone of short spindles, and near the poles there is no apparent order at any mitotic stage. Our data suggest that the kinetochore MTs (KMTs) do not interact directly with nonkinetochore MTs, but that interdigitating MTs from the two spindle poles do interact to form a mechanically stable bundle that connects the poles. As the spindle elongates, the number of MTs decreases while the mean length of the MTs that remain increases. We conclude that the chromosomes of S. pombe become attached to the spindle by kinetochore MTs, that these MTs disappear as the chromosomes segregate, that increased separation of daughter nuclei is accompanied by a sliding apart of anti-parallel MTs, and that the mitotic processes of S. pombe are much like those in other eukaryotic cells.

Initiation and growth of microtubules from mitotic centers in lysed mammalian cells.

Metaphase PtK1 cells, lysed into polymerization-competent microtubule protein, maintain a spindle which will gain or lose birefringence depending on the concentration of disassembled tubulin subunits used in the lysis medium. Concentrations of tubulin subunits greater than the equilibrium monomer value promote a rate and extent of birefringence increase that is proportional to the subunit concentration. Increase in spindle birefringence can be correlated with an increase in tubule number, though the relationship is not strictly linear. Increase in spindle tubule number is due to an vivo-like initiation of tubules at the mitotic centers, as well as tubulin addition onto pre-existing spindle fragments. Colcemid-treated prometaphase cells lysed into polymerization-competent tubulin develop large asters in the region of the centrioles and short tubules at kinetochores, making it unlikely that all microtubule formation in lysed cell preparations is dependent on tubulin addition to short tubule fragments. Asters can also form in colcemid-treated prometaphase cells lysed in tubulin that is incapable of spontaneous tubule initiation, suggesting that the centriolar region serves a tubule-initiator function in our lysed cell preparations. The ability of the centriole to initiate microtubule assembly is a time-dependent process-a ripening effect takes place between prophase and late prometaphase. Ripening is expressed by an increase in the number and length of tubules found associated with the centriolar region.

A comparison of the distribution of actin and tubulin in the mammalian mitotic spindle as seen by indirect immunofluorescence.

Rabbit antibodies against actin and tubulin were used in an indirect immunofluorescence study of the structure of the mitotic spindle of PtK1 cells after lysis under conditions that preserve anaphase chromosome movement. During early prophase there is no antiactin staining associated with the mitotic centers, but by late prophase, as the spindle is beginning to form, a small ball of actin antigenicity is found beside the nucleus; After nuclear envelope breakdown, the actiactin stains the region around each mitotic center, and becomes organized into fibers that run between the chromosomes and the poles. Colchicine blocks this organization, but does not disrupt the staining at the poles. At metaphase the antiactin reveals a halo of ill-defined radius around each spindle pole and fibers that run from the poles to the metaphase plate. Antitubulin shows astral rays, fibers running from chromosomes to poles, and some fibers that run across the metaphase plate. At anaphase, there is a shortening of the antiactin-stained fibers, leaving a zone which is essentially free of actin-staining fluorescence between the separating chromosomes. Antitubulin stains the region between chromosomes and poles, but also reveals substantial fibers running through the zone between separating chromosomes. Cells fixed during cytokinesis show actin in the region of the cleavage furrow, while antitubulin reveals the fibrous spindle remnant that runs between daughter cells. These results suggest that actin is a component of the mammalian mitotic spindle, that the distribution of actin differs from that of tubulin and that the distributions of these two fibrous proteins change in different ways during anaphase.

The distribution of spindle microtubules during mitosis in cultured human cells.

WI-38 and HeLa cells in mitosis have been selected from fixed monolayer cultures and serially sectioned for electron microscopy. Sections perpendicular to the spindle axis permit counting of the number of microtubules at each position on the spindle axis and hence the preparation of tubule distribution profiles. Errors intrinsic to this method are discussed. The changes in the tubule distributions from one mitotic stage to another provide evidence concerning the behavior of the spindle tubules during mitosis. The ratio of the number of tubules passing the chromosomes on the metaphase plate to the maximum number in each half spindle is about 1/2. This ratio changes little in early anaphase, and then decreases in late anaphase at about the same time that a zone of increased tubule number develops at the middle of the interzone. The region where the stem bodies form contains about 3/2 the number of tubules seen elsewhere in the interzone. This ratio is almost constant as the mid-body forms in telophase and then increases to 2/1 in early interphase before the final stages of cytokinesis occur.