Basal bodies

In order to avoid conception, abstinence from sexual intercourse during the fertile period of the menstmal cycle must be practiced (77,104). It has been deterrnined that the fertile period in women occurs before menstmation (105,106), and formulas have been developed to determine the fertile and infertile days of the menstmal cycle. Ovulation has been linked to a cycHc shift in basal body temperature (107), which can be used retrospectively to determine the time of ovulation. 

MTOCs containing highly regular, parallel arrays of microtubules, as seen in centrioles and basal bodies. 

Radial arrays are best exemplified by mitotic half-spindles, which have a central MTOC, the centrosome. The centrosome consists of two centrioles (which are homologous with the basal body) surrounded by dense pericentriolar material (Kalt and Schliwa, 1993). In plant cells, the MTOC of the mitotic spindle consists of dense material only without centrioles. The plus ends of microtubules of the mitotic spindle are directed toward the equator of the cell. Some are free, and others attach to kinetochores on chromatids (see Figure 4). 

Hall, J.L., Ramanis, Z., Luck, D.J.L. (1989). Basal body/centriolar DNA Molecular genetic studies in Chlamydomonas. Cell 59, 121-132. 

FIGURE 1-17 The surfaceofan ependymal cell contains basal bodies (arrows) connected to the microtubules of cilia, seen here in longitudinal section. Several microvilli are also present. X37,000. Inset Ependymal cilia in transverse section possess a central doublet of microtubules surrounded by nine pairs, one of each pair having a characteristic hooklike appendage (arrows). X 100,000. 

The threshold concentration of monomer that must be exceeded for any observable polymer formation in a self-assembling system. In the context of Oosawa s condensation-equilibrium model for protein polymerization, the cooperativity of nucleation and the intrinsic thermodynamic instability of nuclei contribute to the sudden onset of polymer formation as the monomer concentration reaches and exceeds the critical concentration. Condensation-equilibrium processes that exhibit critical concentration behavior in vitro include F-actin formation from G-actin, microtubule self-assembly from tubulin, and fibril formation from amyloid P protein. Critical concentration behavior will also occur in indefinite isodesmic polymerization reactions that involve a stable template. One example is the elongation of microtubules from centrosomes, basal bodies, or axonemes. 

Increases the basal body temperature and inhibit uterine contractions by decreasing sensitivity of myometrium to oxytocin. 

E. Therapeutic response Follicle maturation during follitropin beta therapy is best monitored by daily ultrasonography and daily measurement of serum and/or urine estradiol levels. Ovulation may be clinically confirmed by an increase in serum progesterone as well as an elevation in basal body temperature. 

Progesterone and medroxyprogesterone have been used in the treatment of women who have difficulty in conceiving and who demonstrate a slow rise in basal body temperature. There is no convincing evidence that this treatment is effective. 

Fig. 2 Mitosomes of Giardia intestinalis localized between axonemes (a) of caudal flagella close to basal bodies (w, nucleus). Scale bar = 500 nm. Kindly provided by E. Noh)mkova, Charles University in Prague, Czech Republic...

Basal body of flagella 15 Basal metabolic rate 283... 

FliM and FliN form an additional ring, the cytoplasmic or C-ring, which had been difficult to see in early electron microscopy. As many as 40 of each of these subunits may be present in the ring.42,43 A ring of FliG subunits joins the C-ring to the MS-ring (Fig. 19-3). FliE is also a part of the basal body.253... 

She reviewed my basal body temperature (BBT) chart and wrote me a prescription for fertility herbs from Chinatown. 

Non-ciliated receptors show much variation. Some resemble ciliated receptors in that they have a terminal dendritic bulb with a basal body but no distal cilium (85, 942). Others, as in H. nana (Fig. 2.9), show little structural specialisation and appear to be little more than free nerve endings which may have a single, double or triple structure. Endings which do not penetrate the tegument to the external environment may have a mechanoreceptive or proprioceptive (i.e. receptive to internal stimuli) -rather than chemoreceptive - function (12, 206, 942). 

The one-axoneme type has been shown to develop from the two-axoneme type. Thus, in Phyllobothrium gracile, although during spermatogenesis two basal bodies are formed, one of these is aborted (561). In Echinococcus multilocularis, both basal bodies initiate the formation of an axoneme, but one of these is subsequently aborted during elongation of the other (45, 46). 

Hall JL, Luck DJ, (1995) Basal body-associated DNA in situ studies in Chlamydomonas rein-hardtii. Proc Natl Acad Sci USA 92 5129-5133... 

Fig. S-36 Representations of ccntrioles. basal bodies and axonemes within a cilium. la) Ccntriole/basal body showing the nine sets of triplet microtubules, (h) Cross-section of a cilium/flagellum showing the 9 + 2" array of microtubules and accessory proteins of the axoneme. (c) View of a cell indicating the organizing role of ccntrioles and basal bodies.

An axoneme grows from a preexisting structure called the basal body which appears to be similar in construction to a centriole in the centromere [Pig. 5-36( ). The basal body consists of nine triplet sets of microtubules cross-linked by proteins at regular intervals. There are no central microtubules, but protein spokes radiating inward to a central "hub" can be seen in some cross-sections. 

Each axoneme doublet grows from two of the tubules in each triplet of the basal body. It is not known how the growth of the two central microtubules of the axoneme is controlled, or how the carefully regulated length of the cilia and flagella is monitored. 

Figure I. Structure of a ciliated photoreceptor cell in vertebrates. (A) Scheme of a rod photoreceptor cell. (B) Transmission electronmicroscopy image of a part of a mouse rod photoreceptor cell. The apical extensions of cells of the retinal pigment epithelium (RPE) evolve the tips of photoreceptors light-sensitive outer segments (OS). The OS is linked via a connecting cilium (CC) to an inner segment (IS) which bears the basal body complex (BB) in its apical region. Synaptic terminals (S) link the photoreceptor cell and the 2nd-order neurons, bipolar and horizontal cells. N = nucleus in B, arrow point to axonemal microtubules projecting into the OS. Bar in B = 0.2 p,m...

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