Luận án tiến sĩ ảnh hưởng của nhiệt độ điều kiện oxy thấp và co2 cao lên hô hấp

MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY DANG DIEM TUONG THE EFFECTS OF TEMPERATURE, HYPOXIA ANDHYPERCARBIA ON RESPIRATION AND PHYSIOLOGY OF CLOWN KNIFEFISH CHITALA ORNATA (GRAY, 1831) DOCTORALDISSERTATION MAJOR: AQUACULTURE MAJOR CODE: 9 62 03 01 2018 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY DANG DIEM TUONG THE EFFECTS OF TEMPERATURE, HYPOXIA AND HYPERCARBIA ON RESPIRATION AND PHYSIOLOGY OF CLOWN KNIFEFISH CHITALA ORNATA (GRAY, 1831) DOCTORALDISSERTATION MAJOR: AQUACULTURE MAJOR CODE: 9 62 03 01 Supervisors Prof. TRAN NGOC HAI 2018 LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com Data sheet Title: The effects of temperature, hypoxia and hypercarbia on respiration and physiology of Clown knifefish Chitala ornata (Gray, 1831) Subtitle: PhD Dissertation Author: Dang Diem Tuong Affiliation: College of Aquaculture and Fisheries, Can Tho University, Vietnam Publisher: Can Tho University Publication year: Citation: Tuong, D. The effects of temperature, hypoxia and hypercarbia on respiration and physiology of Clown knifefish Chitala ornata (Gray, 1831). PhD Dissertation, College of Aquaculture and Fisheries, Can Tho University, Vietnam.

Tran Ngoc Hai, College of Aquaculture and Fisheries, Can Tho University, Vietnam. Co-supervisors: Assoc. Do Thi Thanh Huong, Department of Nutrition and Aquatic Products Processing, College of Aquaculture and Fisheries, Can Tho University, Vietnam. Mark Bayley, Zoophysiology, Department of Bioscience, Aarhus University, Denmark.

LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com TABLE OF CONTENTS TABLE OF CONTENTS. vi LIST OF FIGURES. ix LIST OF TABLES .3 Research contents/activities. Temperature and hypoxia.

Temperature and hypoxia: their effects on metabolism of air-breathing fishes 11 3. Hypercarbia and its effect on cardioventilatory responses. Air-breathing fish species. 38 CLOWN KNIFEFISH (CHITALA ORNATA) OXYGEN UPTAKE AND ITS PARTITIONING IN PRESENT AND FUTURE ENVIRONMENTS.

Materials and methods. 63 GILL REMODELING OF CLOWN KNIFEFISH (CHITALA ORNATA) UNDER IMPACT OF TEMPERATURE AND HYPOXIA. 64 i LUAN VAN CHAT LUONG download : add luanvanchat@agmail. Materials and methods.

82 VENTILATORY RESPONSES OF THE CLOWN KNIFEFISH, CHITALA ORNATA, TO HYPERCARBIA AND HYPERCAPNIA. Materials and methods. 102 VENTILATORY RESPONSES OF THE CLOWN KNIFEFISH, CHITALA ORNATA, TO AMBIENT WATER AND AIR HYPERCARBIA, AND HYPERCAPNIA IN DENERVATED FISH. Materials and methods.

132 CONCLUSIONS AND PERSPECTIVES. 132 ii LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com ACKNOWLEDGEMENTS First of all, I would like to give my deep appreciations to Assoc. Do Thi Thanh Huong, Prof. Nguyen Thanh Phuong and Prof.

Tran Ngoc Hai of Can Tho University who supported, encouraged as well as straightened my direction during my study. They have been great teachers who were willing to help me solving my troubles throughout the entire process and without them my PhD thesis would not have been finished. My biggest thank go to Assoc. Mark Bayley who set a fire of passion on science and gave me a direction to become a real physiological scientist.

Moreover, he has made valuable connections between many famous scientists and young passionate scientists all over the world. I myself felt like a real scientist among them that I have been highly inspired during my five-year PhD. I would like to thank Prof. Milsom who have taught me a lot about ventilation and chemoreceptors that contributed haft of my thesis contents.

Working with him was my biggest pleasure and fortune from the start to the end of this iAqua project that I have been luckily involved. My thanks would like to go to Prof. Tobias Wang at Aarhus University and Prof. Jens Randel Nyegaardfrom Aarhus University Hospital who have supported and given me helpful advises and cares during time I have been in Denmark.

I would like to give my sincere thanks to Prof. Atsushi Ishimatsu from Japan who was not only an expected teacher on cannulation in lab, but also a nice friend sharing many life experiences. I also wish to thank staff members of the College of Aquaculture and Fisheries, Can Tho University, Vietnam; and of the Zoophysiology Section, the Department of Biological Science; the Stereology and Microscopy of AarhusUniversity Hospital, Denmark that have supported, and taught me laboratory skills during the time I have studied there. I would like to give my thanks to my friends in iAQUA project, Nguyen Thi Kim Ha and Le My Phuong, who have shared interesting experiences and feeling during time we had been in Denmark.

Phan Vinh Thinh, Le Thi Hong Gam and Cristance Damgaard have supported my studies and brought me laughing moments to overcome stressful time. I would like to thank all hard working students who have helped me in doing research works. Finally, I would like to thank my family, my fiancée and my friends that always love and spiritually support me throughout my research on the way to achieve my PhD and all. And thanks for all sacrificed fish! This thesis was included in iAQUA project funded by the Danish International Development Agency (DANIDA), Ministry Affairs of Foreign Denmark.

iii LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com SUMMARY Climate change is one of the most concerns in scientific research regarding its effects on physiology, growth, adaption and/or extinction of aquatic animals. Chitala ornata is an important species in aquaculture which has been investigated in this study to provide profound knowledge for assessment of elevated temperature and CO2 increase. Respiratory physiology, cardiorespiratory responses, gill morphological adaptation and growth were target parameters to evaluate through four studies. Respiratory responses to elevated temperature and hypoxia have been investigated in the first study.

Oxygen threshold (Pcrit), standard metabolic rate (SMR), specific dynamic action (SDA) and the growth under the effects of predicted elevated temperature (33°C) and average present temperature (27°C) in both normoxia (95% of oxygen saturation) and hypoxia (25% and 35% oxygen saturation) have been carried on C. It has been found that at a worst-case model temperature for Mekong delta did not induce negative impact on respiratory physiology of C. Growth has actually been observed to increase at elevated temperature. Air-breathing oxygen was an important ability of C.

ornata to diminish the effects of a severe hypoxic condition especially at the elevated temperature. It is, however, important to consider that reliance on air-breathing may consequently bring disadvantages to fish such as energetic costs and fail of full oxygen saturation. Ability of gill plasticity in C. ornata under the effects of temperature (33 and 27°C) combining to normoxia (95% oxygen saturation)and hypoxia (25% and 35% of oxygen saturation) applying vertical sections in stereology were examined.

Results have shown that C. ornata was able to transform the gill morphology which interlamellar cell mass (ILCM) was found to increase in the normoxia and decrease at the elevated temperature and in hypoxia. Surface area (SA) of respiratory lamellae was significantly affected by the temperature and hypoxia after one month. Harmonic mean water blood thickness significantly reduced by the hypoxia after one month while that reduction induced by the temperature took two months to have significant effects.

An anatomic diffusion factor (ADF) was found 4-fold higher at 33°C in hypoxia comparing to 27°C in normoxia. The surface area of C. ornata gills was consistent with those of air-breathing fish. These results found in C.

ornata support the hypothesis of anciently long-term existence of the gill remodeling mechanism. iv LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com Hypercarbia and hypercapnia induced cardiorespiratory responses promoted by CO2/H+-sensitive chemoreceptors of C. ornata have been investigated in the third study. ornata has been exposed to acid water (pH=6), hypercarbic (CO2 increase, ~pH=6) and hypercapnic condition (injection of acetazolamide) at normocarbia.

We measured the changes of air-breathing frequency, gill ventilation frequency, heart rate, arterial blood pressure, and blood pH and plasma CO2. In acidosic condition, C. ornata did not respond significant changes of any observed parameters. It has been found that C.

ornata responded to the environmental hypercarbia and blood hypercapnia which dramatically increased air-breathing frequency but no significant changes of the gill ventilation, and revealed a modest bradycardia and fall in the arterial blood pressure. The blood [H+] and plasma PCO2 have been found to increase in both hypercarbia and acetazolamide. The acetazolamide results provide an evidence of internally oriented cardiorespiratory CO2/H+ chemoreceptors existing in the facultative air-breathing, C. Investigating cardioventilatory responses under the effects of CO2 injection into air-breathing organ (ABO) of intact C.

ornata, and the effects of the hypercarbia and hypercapnia on denervated C. ornata were conducted in the last study. The ascending CO2 percentages mixed with the air were injected into ABO. Denervation of IXth and Xth cranial nerves were performed in C.

ornata which were exposed to the hypercarbia (CO2 increase ~pH=6) and the acetazolamide (internal [H+] and PCO2 increase) after 24h of recovery. It has been found that both intact and denervated C. ornata responded significant air- breathing frequencies. Bradycardia and no significant changes of the gill ventilations were also found in all treatments.

The increase of internal [H+]and PCO2 were found in all treatments of CO2 injection into ABO, and the hypercarbia and hypercapnia. The results of CO2 injection into ABO of the intact fish, and the hypercarbia and hypercapnia in the denervated fish additionally gave documentation to confirm the existence of internally oriented cardiorespiratory CO2/H+-sensitive chemoreceptors and were indirectly inferable to central chemoreceptors. v LUAN VAN CHAT LUONG download : add luanvanchat@agmail.com TÓM TẮT Biến đổi khí hậu là một trong những vấn đề được quan tâm nhất trong nghiên cứu khoa học về phương diện ảnh hưởng lên sinh lý, tăng trưởng, thích nghi và/ hoặc diệt vong của động vật thủy sản. Cá thát lát còm (Chitala ornata) là một loài quan trọng trong nuôi trồng thủy sản đã được chọn trong nghiên cứu này để cung cấp các thông tin chuyên sâu về đánh giá tác động của sự tăng nhiệt độ và nồng độ CO2.

Các chỉ tiêu sinh lý hô hấp, các phản ứng hô hấp tim mạch, sự thích nghi hình thái mang cá và tăng trưởng là các chỉ tiêu đã được thực hiện để đánh giá ảnh hưởng của biến đổi khí hậu thông qua bốn nghiên cứu. Phản ứng hô hấp của cá theo sự tăng nhiệt độ và nồng độ oxy thấp được thực hiện trong nghiên cứu thứ nhất. Ngưỡng oxy (Pcrit), trao đổi chất cơ bản (SMR), tác động của tiêu hóa thức ăn lên hoạt động hô hấp (SDA) và tăng trưởng của cá thát lát dưới ảnh hưởng của nhiệt độ dự báo (33°C) và nhiệt độ trung bình hiện tại (27°C) kết hợp với hàm lượng oxy bão hòa và oxy thấp đã được thực hiện. Kết quả cho thấy ở mức nhiệt độ dự báo cao nhất ở vùng đồng bằng sông Cửu Long sẽ không ảnh hưởng tiêu cực lên sinh lý hô hấp của cá.

Tăng trưởng của cá tăng ở mức nhiệt độ cao. Khả năng hô hấp khí trời là đặc điểm quan trọng giúp cá có thể giảm bớt ảnh hưởng của hàm lượng oxy thấp, đặc biệt trong môi trường nhiệt độ tăng. Tuy nhiên, điều quan trọng cần cân nhắc là việc dựa vào khả năng hô hấp khí trời có thể dẫn tới các hậu quả bất lợi cho cá như hao tốn năng lượng và giảm khả năng bão hòa oxy trong máu. Khảo sát khả năng biến đổi cấu trúc mang của cá dưới ảnh hưởng của nhiệt độ (33 và 27°C) kết hợp với môi trường oxy bảo hòa và thiếu oxy áp dụng phương pháp mô học lập thể được tiến hành trong thí nghiệm này.

Kết quả cho thấy cá có biến đổi hình thái mang bằng cách tăng sinh hoặc giảm sinh số lượng các tế bào ở giữa lá mang thứ cấp (ILCM) trong môi trường oxy bão hòa, và môi trường thiếu oxy và nhiệt độ cao. Diện tích bề mặt (SA) hô hấp của mang bị ảnh hưởng nhiều bởi nhiệt độ và tình trạng thiếu oxy sau 30 ngày nuôi.