29-34 29 A. J. El- Waily Bull. Iraq nat. Hist. Mus. (2001) 9 (3): 29-34 ANNUAL CYCLE IN LIVER WEIGHT OF MARSH FROG RANA RIDIBUNDA PALLAS, 1771 Alwan J. El-Wailly Biology Department, College of Education (Ibn Al-Haitham), University of Baghdad, Baghdad, Iraq ABSTRACT The dry weight of the liver of Rana ridibunda was expressed as percentage of the dry weight of the body. The female liver weight always exceeds that of the male, except in July and September. The difference between males and females for the whole year, regardless of months, was not significant. Livers of both sexes were relatively large prior to hibernation (December), decreased during hibernation (January and February) until a minimum weight in March (post-hibernation). The increase of liver weight during December is apparently simply to meet the metabolic requirements for survival during hibernation. The percent reduction in liver weight during hibernation was 1.081% in males and 1.356% in females. The decrease in liver weight during the hibernation months may be attributed to the utilization of liver glycogen. The rise in mean weight from August to October indicates that marsh frogs, after spawning, were actively feeding. INTRODUCTION The liver in amphibia represents an important organ, which stores depot substances. Many workers have noted seasonal changes which occur in the liver of the frog. According to Smith (1950), the first report on the occurrence of marked seasonal changes in glycogen contents of frogs was in 1899. The literature provides several works concerning the seasonal changes of liver weight (Maruyama, 1979; Morton, 1981), liver metabolism (Schlaghecke and Blum, 1978), lipid composition and protein content of the liver (Milone et al., 1978, 1983), and cyclic changes in liver glycogen (Byrne and White, 1975). Experiments mostly were carried out on the biochemistry and physiology of R. ridibunda (Conlon et al., 1993; Munoz et al., 1993; Vitanova et al., 1993). The objective of the present study is to through a light on the quantitative descriptive of the annual cycle in liver weight of the marsh frog R. ridibunda, as it appears that this frog is one of the most successful anurans in Iraq. MATERIALS AND METHODS Frogs were collected from superficial waters, brooks, ponds and other places where the water is nearly stagnant, found in various parts of Baghdad and its suburbs. A total of 167 specimens of R. ridibunsa (82 males and 85 females) were captured throughout the year 1994. No samples were collected in June. The collected frogs were transported to the laboratory for measurments and sex determination. Liver and stomach contents were removed. All specimens and livers were dried at 70 oC until no further loss of weight occurred, usually 24 hours. The weight of the liver has been deducted from the total body weight. The dry weight of the liver was expressed as percentage of the dry weight of the body. The differences in the 30 A Liver weight of marsh frog mean values were evaluated by the student t-test. The means are considered statistically significant at the 95% confidence level. RESULTS Table (1) shows the mean percent liver weight of both males and females of marsh frog. The females’ liver weight always exceeded that of the males, except in July and September. However, the difference between males and females for the whole year, regardless of months, was not significant (P>0.05). In females, all mean weights in January, April and December were significantly greater than in males (P<0.5). The marsh frog, in Baghdad 1994, entered hibernation during the last week of December and emerged during the first week of March. The mean temperature of January and February was 6.1 ± 7.2 °C and 8.6 ± 4.3 °C, respectively. Livers of both sexes exhibited annual changes in relative weight. They were relatively larger prior to hibernation (December), 1.857% in males and 2.288% in females, decreased during hibernation (January and February) to reach a minimum weight in March (posthibernation), 0.786% in males and 0.932% in females. All mean weights of all individuals, regardless of sex, in December were significantly greater than those of March. The first obvious increase took place in April and May, decreased in July, than increased continuously until October. There was a significant change in liver weights between sexes in April but not in May. Table (1): Percent liver weight (gm) of R. ridibunda. Month Males Females Mean S. E. No. Mean S. E. No. January 1994 1.492 0.322 7 2.019 0.467 6 February 0.950 0.227 5 1.168 0.236 5 March 0.786 0.183 8 0.932 0.145 10 April 1.222 0.338 9 1.843 0.503 8 May 2.038 0.480 11 2.337 0.407 12 June -- -- -- -- -- -- July 1.985 0.745 7 1.438 0.415 8 August 1.927 0.329 9 2.200 0.257 11 September 2.372 0.431 8 2.268 0.347 7 October 2.741 0.231 6 2.896 0.107 6 November 1.573 0.337 8 1.755 0.308 7 December 1.867 0.199 4 2.288 0.296 5 Dry liver weight * Percent liver weight = ------------------------------------ X 100 Dry body weight The liver weight shows a remarkable rise in October with a maximum weight (2.741% in males and 2.896% in females), than decreased in November and again increased in December (Fig.1). In females, the mean weight in December was significantly greater than in males. 31 A. J. El- Waily DISCUSSION The results show that livers in both sexes of R. ridibunda exhibited an increase in December (prehibernation). The increase of liver weight during this month is apparently simply to meet the metabolic requirements for survival during hibernation. It has been known from many years that fat and glycogen are accumulated in amphibians prior to hibernation (Smith, 1950). The decrease in liver weight during the hibernation months (57.90% of liver weight in males and 59.25% in females) may be attributed to the utilization of liver glycogen. Liver glycogen may be utilized to provide the energy needed for gametogenesis and for storage of food reserves in the ovary (Smith, 1950). Bush (1963) demonstrated that R. pipiens could metabolize, during hibernation, about 75% of liver carbohydrates before death. It is possible that the increase of liver weight during April and May (after reproduction) is the direct effect of food intake as most of the stomachs examined at this time were found to be full food materials. The rise in mean weight from August to October indicates that March frogs accumulate glycogen to serve them as energy supply for the next breeding season (Morton, 1981). ACKNOWLEDGEMENTS Thanks are due to Prof. Dr. Furhan T. Mhaisen and Dr. Emad Al-Mukhtar of the College of Education (Ibn Al-Haitham), University of Baghdad for their critical reading of the manuscript and their useful suggestions. LITERATURE CITED Bush, F.M. 1963. Effect of light and temperature on the gross composition of the toad, Bufo fowleri. J. Exp. Zool., 153:1-13. Byrne, J.J. & White, R.J. 1975. Cyclic changes in liver and muscle glycogen, tissue lipid and blood glucose in a naturally occurring population of Rana catesbeiana. Comp. Biochem Physiol., 50A:709-715. Colon, J.M., Tonon, M.C. & Vaudry, H. 1993. Isolation and structural characterization calcitonin gene related peptide from the brain and intestine of the frog, Rana ridibunda. Peptides, 14(3):581-586. Maruyama, K. 1979. Seasonal cycle in organ weights and lipid levels of the frog, Rana nigromaculata. Annot. Zool. Jap., 52(1):18-26. Milone, M., Caliendo, M.F., Rostogi, R.K. & Chieffi, G. 1978. Annual variations in the total lipid and protein content of the liver, fat body, overy and plasma of the female frog (Rana esculenta) J. Endocr., 78:165-169. Milone, M., Caliendo, M.F., Rostogi, R.K. & Chieffi, G. 1983. Seasonal lipid composition in the liver fat body and gonads of Rana esculenta. Boll. Zool., 50:227-234. Morton, M.L. 1981. Seasonal changes in total body lipid and liver weight in the Yosmite toad Bufo canorus. Copeia, 1:234-238. Munoz, M., Munoz, A. & Gonzalez, A. 1993. Distribution, morphology and central projections of the mesencephalic trigeminal neurons in the frog Rana ridibunda. Anat. Rec., 235(1):165-177. 32 A Liver weight of marsh frog Schlaghecke, R. & Blum, V. 1978. Seasonal variation in liver metabolism of the green frog, Rana esculenta (L.). Experientia, 34:456-457. Smith , C . L . 1950 Seasonal changes in blood sugar , fat body , liver glycogen , and gonads in the common frog , Rana temporaria .J. Exp . Bio. , 26: 412- 426 . Vitanova, I., Kunenova, P., Ponova, E., Mitova, I. & Belcheva, S. 1993. Comarative investgation of ratinal responses to brief light stimuli. 2-amino-4-phosphonobutyate studies. 1. Frog ratina, Rana ridibunda. Comp. Biochem. Physiol., C. 104(2):289- 297. 33 A. J. El- Waily Bull. Iraq nat. Hist. Mus. (2001) 9 (3): 29-34 Rana ridibundaت السنوية لوزن كبد ضفدع المستنقعات التغيرا علوان جاسم الوائلي قسم علوم الحياة، كلية التربية، ابن الهيثم، جامعة بغداد الخالصة كـان وزن كبــد . اسـتخرج الـوزن اجلــاف لكبـد ضـفدع املســتنقعات نسـبة اىل وزن اجلسـم اجلــاف وبغــض النظــر عــن . أوزان كبــود شــهري آب و أيلــولاألنثــى دائمــاً يزيــد علــى وزن كبــد الــذكر عــدا أوزان كبـــود الضـــفادع خـــالل كـــل شـــهر علـــى حـــده مل ختتلـــف أوزان كبـــود الـــذكور عـــن أوزان كبـــود نسـبيا قبـل سـبا ا يف شـهر كـانون كبـرية كانت كبود اجلنسني. اإلناث خالل السنة اختالفا معنويا السـبات يف شــهري كـانون الثـاين وشـباط حـىت وصــلت اىل األول وقـد اخنفضـت أوزان الكبـود أثنـاء الزيـــادة يف وزن الكبـــد لشـــهر كـــانون األول اىل تعـــزى و . اقـــل وزن هلـــا بعـــد الســـبات يف شـــهر آذار بلغــت نســـبة اخنفـــاض وزن . البقـــاء علـــى قيــد احليـــاة خــالل فـــرتة الســـباتلبــات حاجــة احليـــوان ملتط ى نســبة اخنفــاض عــز يف اإلنــاث، وقــد ت% ١,٣٥٦يف الــذكور و % ١،٠٨١ الكبــد أثنــاء الســبات وزن الكبد أثنـاء اشـهر السـبات اىل اسـتهالك الكاليكـوجني املوجـود يف الكبـد ويعـود سـبب ارتفـاع معـدل وزن الكبــد مـن شــهر آب اىل تشـرين األول اىل إن ضــفدع املسـتنقعات كــان يتغـذى بنشــاط .بعد فرتة التناسل 34 A Liver weight of marsh frog