威傑張 | National Dong Hwa University (original) (raw)

Papers by 威傑張

Theriogenology, 2009

Cryopreservation of germplasm of aquatic species offers many benefits to the fields of aquacultur... more Cryopreservation of germplasm of aquatic species offers many benefits to the fields of aquaculture, conservation and biomedicine. Although successful fish sperm cryopreservation has been achieved with many species, there has been no report of successful cryopreservation of fish embryos and late stage oocytes which are large, chilling sensitive and have low membrane permeability. In the present study, cryopreservation of early

Cryobiology, 1995

Two related studies on chilling and nonfreezing storage of zebrafish (Brachydanio rerio) embryos ... more Two related studies on chilling and nonfreezing storage of zebrafish (Brachydanio rerio) embryos were undertaken. In the first part of the investigation, 10 developmental stages of zebrafish embryos were studied for chilling sensitivity. Early developmental stages were the most sensitive to chilling, with approximately 50% of 3-, 7-, 15-, 20-, and 27-h (heartbeat-stage) embryos being killed by exposure to 0°C for periods of 0.2, 4, 14, 16, and 20 h, respectively. Heartbeat-stage embryos tolerated a temperature of 0°C for up to 10 h without adverse effect, but embryo survival was significantly reduced at subzero temperatures. While 27- to 40-h stage embryos showed similar sensitivity to chilling with 56.9 ± 12.1 to 54.5 ± 5.5% survival, 45- to 49-h (prehatch) stage embryos showed increased sensitivity with 28.4 ± 6.3 to 11.7 ± 4.6% survival after 18 h at 0°C. In the second part of the investigation, the cryoprotective effects of various media on chilling sensitivity were studied. The presence of sucrose or trehalose slightly enhanced cooling tolerance of the embryos. Methanol proved to be an optimal cryoprotectant for nonfreezing storage of embryos at zero and subzero temperatures. The optimal methanol concentration, when supplemented with sucrose (0.1 M), was temperature dependent, being 1 M at 0°C, 2 M at - 5°C, 3 M at -10°C, and 5 M at - 15°C, with embryo survival of 30.2 ± 3.5, 28.6 ± 5.8, 27.3 ± 12.1, and 14.3 ± 4.2% after storage for 48, 24, 6, and 1 h, respectively. Survival of supercooled embryos decreased with storage time and temperature. No embryo survived exposure for 72 h at 0°C or 1 h at -20°C. The loss of embryo viability may be related to chilling injury, cryoprotectant toxicity, osmotic stress, or other factors.

Theriogenology, 2003

Stage-dependent chilling sensitivity has been reported for many species of ®sh embryos. Most of t... more Stage-dependent chilling sensitivity has been reported for many species of ®sh embryos. Most of these studies reveal that developmental stages beyond 50% epiboly are less sensitive to chilling, but the chilling sensitivity accelerates rapidly at subzero temperatures. In this study, the effects of methanol and developmental arrest on chilling injury were studied using zebra®sh (Danio rerio) embryos at 64-cell, 50% epiboly, 6-somite, prim-6 and long-bud stages. Embryos were exposed to methanol or anoxic conditions before they were cooled to 0 or À5 8C with slow (1 8C/min), medium (30 8C/min) or fast ($300 8C/min) cooling rates and were held at these temperatures for different time periods. Embryo survival was evaluated in terms of the percentage of treated embryos with normal developmental appearance after 3-day culture. Experiments on the effect of methanol on chilling sensitivity of the embryos showed that the addition of methanol to embryo medium increased embryo survival signi®cantly at all developmental stages and under all cooling conditions. Higher concentration of methanol treatment generally improved embryo survival when embryos were cooled at a fast cooling rate of 300 8C/min. Experiments on the effect of developmental arrest on chilling sensitivity of embryos showed that embryos at 50% epiboly and prim-6 stages underwent developmental arrest almost immediately after 15 min oxygen deprivation. After 4 h in anoxia, the survival rates of the embryos were not signi®cantly different from their respective aerobic controls. Anoxia and developmental arrest had no effect on the chilling sensitivity of zebra®sh embryos. #

Cryobiology, 1992

Drosophila embryos manifest unusually high sensitivity to chilling in that they are killed with i... more Drosophila embryos manifest unusually high sensitivity to chilling in that they are killed with increased rapidity by exposure to temperatures between 0 and -25 degrees C in the absence of ice formation. Thus, 50% of 15-h eggs succumb in 35, 4, and 1 h at 0, -9, and -15 degrees C, respectively. The sensitivity becomes substantially greater in embryos at stages of development earlier than 12 h, especially at 3 and 6 h. The killing kinetics at given subzero temperatures between 0 and -25 degrees C are characterized by a shoulder followed by a more-or-less linear decrease in survival with time. The lower the temperature, the shorter the shoulder and the faster the postshoulder decline. The rate of both components follows Arrhenius kinetics, i.e., plots of log rate vs 1/absolute temperature are linear, the slopes being proportional to the activation energy. In both cases the activation energy is high and negative; namely, -46.5 kcal/mol for the shoulder length and -24.7 kcal/mol for the postshoulder inactivation. Negative activation energies are unusual, and according to absolute reaction rate theory, they exist only when the entropy of activation is negative, which suggests that the activated state is more ordered. By combining the duration of the shoulder as a function of time and temperature with the rate of postshoulder inactivation, one can compute survival as a function of temperature for embryos cooled at various rates. For those cooled at less than or equal to 1 degree C/min, the computed curve of survival vs temperature agrees closely with observed survivals. But for embryos cooled at approximately 10 degrees C/min, the drop in survival occurs some 7 to 10 degrees above that computed. Embryos exposed to 0 degree C for greater than 5 min undergo conditioning that renders them more resistant to subsequent exposure to lower temperatures, and those cooled at 10 degrees C/min presumably lack sufficient time at 0 degree C to undergo such conditioning; hence the discrepancy between observed and computed survivals. As a test of the possibility that chilling injury is a consequence of the loss of synchrony of coupled reactions involved in embryological development, embryos were rendered anoxic prior to chilling, a treatment that has been shown by Foe and Alberts to reversibly halt development of early stages. Although anoxia somewhat reduced chilling injury in 6-h eggs, it had no effect on 15-h eggs.(ABSTRACT TRUNCATED AT 400 WORDS)

Journal of Experimental Botany, 2006

A combination of hot water (a rinse at 62 8C for 20 s) and conditioning (pre-storage at 16 8C for... more A combination of hot water (a rinse at 62 8C for 20 s) and conditioning (pre-storage at 16 8C for 7 d) treatments synergistically reduced chilling injury development in grapefruit (Citrus paradisi, cv. 'Star Ruby') during cold storage at 2 8C, suggesting that the treatments may activate different chilling tolerance responses. To study the molecular mechanisms involved, chilling-and conditioning-responsive genes were isolated by polymerase chain reaction (PCR) cDNA subtraction, cDNA libraries were constructed from hot water-and conditioning-treated fruit, and cDNA sequencing was used to identify putative stressresponsive and chilling tolerance genes. PCR cDNA subtraction revealed the identification of 17 chillingresponsive and heat-and conditioning-induced genes, and the expression patterns of 11 additional stressrelated genes, antioxidant defensive genes, and genes encoding enzymes involved in membrane lipid modifications were characterized. It was found that hot water and conditioning treatments had little effect on gene expression by themselves, but rather had a priming effect, and enabled the fruit to activate their defence responses after subsequent exposure to chilling. RNA gel blot hybridizations revealed that the expression patterns of eight genes, including HSP19-I, HSP19-II, dehydrin, universal stress protein (USP), EIN2, 1,3;4-b-D-glucanase, and superoxide dismutase (SOD), were specifically regulated by the heat treatment, and four genes, including fatty acid desaturase2 (FAD2) and lipid transfer protein (LTP), were specifically regulated by the conditioning treatment. Furthermore, four more genes were identified, including a translation initiation factor (SUI1), a chaperonin, and alcohol dehydrogenase (ADH), that were commonly regulated by both heat and conditioning treatments. According to these data, it is suggested that pre-storage heat and conditioning treatments may enhance fruit chilling tolerance by activating different molecular mechanisms. The hot water treatment activates mainly the expression of various stress-related genes, whereas the conditioning treatment activates mainly the expression of lipid membrane modification enzymes.

Annual Review of Plant Physiology, 1984

ISRN obstetrics and gynecology, 2011

With the evolution of the treatment of malignant neoplasms, the survival rates of patients underg... more With the evolution of the treatment of malignant neoplasms, the survival rates of patients undergoing chemo- or radiotherapy are increasing. The continuous development of techniques of assisted human reproduction has led to important strategies in an attempt to maintain reproductive function in patients subjected to treatment of neoplastic diseases, among them cryopreservation of embryos, gametes, and ovarian cortical tissue. The freezing of ovarian tissue is currently being proposed with the primary purpose of preserving ovarian function in these patients. Currently, the major challenge of groups working with preservation of fertility is the use of cryopreserved ovarian tissue after disease remission. The main alternatives presented today are the implantation of hetero- or orthotopic tissue and isolation of immature follicles from ovarian tissue followed by in vitro maturation and assisted reproduction procedures.