The importance of precise information and knowledge on the initial estimates (IEs) in modeling has not been paid its due attention so far. By focusing on the IE, this tutorial may serve as a practical guide for beginners in pharmacometrics. A 'good' set of IEs rather than arbitrary values is required because the IEs where NONMEM kicks off its estimation may influence the subsequent objective function minimization. To provide NONMEM with acceptable IEs, modelers should understand the exact meaning of THETA, OMEGA and SIGMA based on physiology. In practice, problems related to the value of the IE are more likely to occur for THETAs rather than the random-effect terms. Because it is almost impossible for a modeler to give a precise IE for OMEGAs at the beginning, it may be a good practice to start at relatively small IEs for them. NONMEM may fail to converge when too small IEs are provided for residual error parameters; thus, it is recommended to give sufficiently large values for them. The understandings on the roles, meanings and implications of IEs even help modelers in troubleshooting situations which frequently occur over the whole modeling process.
Physiology

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Physiology*

No abstract available.
Physiology*

No abstract available.
Physiology

Jaw ; physiology ; Muscles ; physiology

OBJECTIVETo study four kinds of germplasm resources of Codonopsis pilosula and provide the basal mating systems data for the breeding and cultivation of C. pilosula.

METHOD0.5% TTC (2,3,5-triphenyl tetrazolium chloride) solution was used for the pollen viability test and benzidineand-H2O2 [1% benzidine in 60% ethanol,hydrogen peroxide (3%), and water, 4:11:22] was used for estimation of the stigma receptivity. The mating systems were tested by out crossing index (OC1), pollen-ovule ratio (P/O) and pollination by bagged and emasculated in the field.

RESULTThe pollen viability of C. pilosula reached highly about 80% when the pollen staying in the anther, 2-3 days before the petals opening. The anther began scattering pollen before the day of the petals opening, the pollen viability was the highest about 95%, the pollen stick thickly aroud the stigma and quickliy lost in the next day. The stigma life-span was about 4-5 days, the optimal time for pollination was the first day of the petals opening, when the stigma was highly sticky and yellow. The value of out crossing index (OC1) was 4, pollen-ovule ratio was between 104.84-185.75. The natural fructification rate of cross-pollination by emasculated-treatment was 25.6% 42.4%. The fructification rate and compatible index of self-pollination by bagged- treatment were about 3.3%-6.7% and 3.0-21.8.

CONCLUSIONThe mating system of C. pilosula is mixed with self-pollination and cross-pollination, prone to cross-pollination. The compatibility of self-pollination is high. The difference of maturing period of pistil and stamen and the lack of polen amount cause low fructification rate of self-pollination.

Codonopsis ; physiology ; Flowers ; physiology ; Ovule ; physiology ; Plants, Medicinal ; physiology ; Pollen ; physiology ; Pollination ; physiology ; Reproduction ; physiology

OBJECTIVECurrent study was conducted to investigate the seed physiological characteristics of Tulipa edulis and improve germination rate.

METHODAnatomical characteristics was observed. Seed water absorption curve was tested by soaking method. Dynamic of embryo development and germination rate as well as germination index under different conditions were recorded. And the biological test of cabbage seed was used for detecting the germination inhibitors.

RESULTThe embryo rate of newly matured seeds was about 10%, and there was no obstacle of water absorption on testa of T. edulis. The optimum method for embryo development was exposure to 300 mg x L(-1) gibberellin solution for 24 hours, and stratification at 25 degrees C for 70 days followed by stratification at 5 degrees C for 40 days. The germintion rate and germination index of dormancy-broken seeds under the dark environment at 10 degrees C and 15 degrees C were significantly higher than those under other conditions. Additionally, there were some germination inhibitory substances in dry seeds.

CONCLUSIONThe seed of T. edulis can be classified as having complex morphophysiological dormancy, and the morphological embryo dormancy played a leading role. Warm and cold stratification resulted in a fast dormancy breaking effect, and a high germination rate more than 90% could be obtained under the optimum conditions.

Germination ; physiology ; Seeds ; physiology ; Tulipa ; physiology

OBJECTIVETo find the sexual reproduction characteristics and improve the seed propagation and new variety breeding of Fritillaria cirrhosa.

METHODFlower, anther and pistil development were observed. Pollinating in different development period and bagging were used to measure stigma maturity situation and natural outcrossing rate.

RESULTS AND CONCLUSIONIt took 12 days from floral bud emergency to finished flowering. It was observed that anther opened in longitudinal direction and pollen was ejected for 2-4 days continuously. Pistil matured earlier, and chapiter could be fertilized from middle bud stage the third day after flowering, but the most suitable time was 2-3 day after the corolla opening. The natural outcrossing rate was 81.9%. F. cirrhosa is a typical xenial plant.

Flowers ; physiology ; Fritillaria ; physiology ; Pollination ; physiology

OBJECTIVETo provide theoretical basis for artificial cross breeding of Angelica dahurica from Sichuan and Hebei Province, the characteristics of stigma receptivity and the viability and life-span of pollen were studied.

METHODThe viability and life-span of pollen were evaluated by TTC (2, 3, 5-triphenyl tetrazlium chloride) test, and the stigma receptivity was estimated by benzidine-H2O2 method.

RESULTThe pollen viability of A. dahurica from Sichuan and Hebei provinces was increased gradually since the bud stage, but those levels had since subsided after the pollen release from craze antheral. There was a little difference in the pollen viability of A. dahurica from Sichuan at different branches. While the order of the pollen viability of A. dahurica from Hebei was main stem < first-order branching < second-order branching. At room temperature, the pollen viability of both decreased during time of anthers dehiscing but also above 50% after 5 days. Compared with 4 degrees C and room temperature, conservation at - 20 degrees C could extend life of the pollen. The stigma had receptivity in 4th day and reached the highest level in the 6th day after blooming.

CONCLUSIONThe optimum artificial pollination times of A. dahurica was 6 days after blooming and choose the pollen in the peak stage of anthers dehiscing.

Angelica ; physiology ; Flowers ; physiology ; Pollen ; physiology

To determine the optimal condition of pollen germination. The pollen of Prunella vulgaris was cultured in vitro. Pollen germination rates were recorded using 10% H3BO4, 30% Ca(NO3)2, 20% MgSO4 and 10% KNO3 as the basic mineral medium with PEG of different molecular weight, sucrose of various density and multiple pH value. The rates were also measured under different cultivation temperature and pollen acquisition time. The optimal condition of pollen germination is 10% H3 BO4, 30% Ca(NO3)2, 20% MgSO4, 10% KNO3, and 25% PEG-4000 as the medium, with pH about 6. 5 and pollen acquired at the beginning of blossom.
Flowers ; physiology ; Pollen ; physiology ; Prunella ; physiology