Asian Pac J Trop Med 2014; 7(Suppl 1): S137-S142
S137
Contents lists available at ScienceDirect
Asian Pacific Journal of Tropical Medicine journal homepage:www.elsevier.com/locate/apjtm
Document heading
doi: 10.1016/S1995-7645(14)60220-0
place and tail length evaluation in N aja oxiana, M acrovipera lebetina, and Montivipera latifii H eart
1*
Alireza Nasoori
, Ali Taghipour2, Delavar Shahbazzadeh1, Abdolhossein Aminirissehei3, Sharif Moghaddam4,5
Biotechnology Research Center, Department of Medical Biotechnology, Venom and Toxin Unit, Pasteur Institute of Iran, Tehran, Iran
1
Department of Clinical Sciences, Faculty of Veterinary Medicine, Islamic Azad University, Karaj Branch, Rajaee Shahr, Moazen Blvd., Karaj, Iran
2
Pasteur Institute of Iran, Production and Research Complex, Biotechnology Processes Developing Center, 25th km. Tehran-Karaj Hwy. Karaj, Iran
3
Discipline of Linguistics, the University of Adelaide, Australia
4
Department of English, Faculty of Sciences & Research, the I. Azad University, Tehran, Iran
5
ARTICLE INFO
ABSTRACT
Article history: Received 23 Apr 2014 Received in revised form 3 May 2014 Accepted 13 Jun 2014 Available online 27 Aug 2014
Objective: To evaluate a) heart place and tail length, b) their correlations with other biometrics, c) sexual differences in those features, in regard to cardiovascular system in a number of snakes from Iran, about which there is little information. Methods: We studied the fresh mortalities of snakes including 14 Naja oxiana (N. oxiana), 23 Macrovipera lebetina, and one male Montivipera latifii acquired from the Serpentatium of Pasteur Institute of Iran. In this respect, each specimen first was weighted, and then its ventral side of the integument was incised, and heart place was measured. Subsequently, other biometrical features such as total length, TAL, and snout-vent length were measured. Results: The results showed that heart place in N. oxiana, Macrovipera lebetina and Montivipera latifii was about 18%, 32% and 30%, and also TAL constituted about 16%, 11% and 7% of total body length, respectively. Moreover, females indicated anterior heart place and shorter tail than males. Furthermore, the measures and correlations indicated few differences between N. oxiana and typical terrestrial species. Conclusions: The results denoted that in order to overcome hemocirculatory perturbations in vertical orientation while hooding and head raising behavior, N. oxiana need to have more important features than short heart to head distance and long tail. In addition, it gave the sexual differences in heart place and tail length between males and females. It is suggested that in ophidian cardiovascular studies the animals be grouped based upon their sex.
Keywords: Heart place Tail length Cardiovascular system Sexual differences Snake
1. Introduction Snakes have tubular and elongated bodies inside which cardiovascular system can be considered as a long fluidfilled tube[1,2]. T his morphology makes them liable to hemodynamic imbalances resulting from gravitational force changes such as things happen while climbing, or adopting vertical posture[1,3-5]. There are some anatomical *Corresponding author: Alireza Nasoori, Doctor of Veterinary Medicine (DVM), Biotechnology Research Center, Department of Medical Biotechnology, Venom and Toxin Unit, Pasteur Institute of Iran, Tehran, Iran. Tel: +982166480780, +989126957229 E-mail: [email protected], [email protected] Foundation Project: Supported by the Pasteur Institute of Iran (Grant No. 556).
traits with which the snakes can frequently experience gravitational alterations, such as shorter heart to head distance[1,5-7], and relatively long tail[2,6,8,9]. Previous studies have clearly shown that when snakes are tilted in head-up position, they undergo circulatory disturbances resulting from increased hydrostatic blood pressure due to blood column formation above their heart [3,5,6,10,11]. Therefore, head raising behavior of cobra, which is commonly known as terrestrial species[7,12], predisposes the snake to blood column formation above its heart. S o, cobra is expected to possess a number of features enabling it to overcome the hemodynamic perturbations. On the other hand, terrestrial vipers, in spite of being terrestrial, possess a number of morphological traits,
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Alireza Nasoori et al./Asian Pac J Trop Med 2014; 7(Suppl 1): S137-S142
such as low arterial pressure, tendency to suffer from passive blood congestion in hind part of the body, rather middle-located heart, long and vascularized trachea, and consequently lack of cardiovascular tolerance to upright posture, which are dissimilar to those of terrestrial species[1,5,7,10,13]. A number of former studies have already indicated sexual dimorphism in external features of ophidian body[14-19]. Nevertheless, to the best of our knowledge, few studies have focused on sexual differences in visceral organs[20,21], such as heart, and their possible effects on cardiovascular system. Therefore, we conducted the current research in order to study the biometrical features in Naja oxiana (N. oxiana), Macrovipera lebetina (M. lebetina) and Montivipera latifii ( M. latifii ) concerning heart to head distance and tail length ( TAL ) , and their correlations with each of total body length, snout-vent length and body mass (BM), in males and females, in order to evaluate their importance in cardiovascular system, about which there is little information. 2. Materials and methods I n this research, we studied 23 adult M. lebetina
( including 15
males and 8 females), 14 adult N. oxiana males and 8 females), and a male M. latifii, kept in the Serpentarium of Venom and Toxin Research L ab, P asteur I nstitute of I ran. T hey were all of I ran herpetofauna [22-25] . N. oxiana and M. lebetina were obtained from K horasan P rovinces, northeast of I ran, and M. latifii from T ehran P rovince, central parts of Iran. The snakes were fed with alive and dead rodents. T he specimens studied in our research were of fresh mortalities obtained from the S erpentarium. T hey all were studied on a table covered with plastic, and the measurements were carried out by the same person and the same measuring instruments. E ach specimen was weighed with a digital scale (A&D EK-1200 i NTEP Jewelry Buyer Scale, USA). Afterward, it was placed on the dorsal side on a piece of plastic on a table, and the distances from the tip of snout to vent (snout-vent length, SVL) and to tip of tail (total length, TOL) were accurately measured by a measuring tape, and noted down. Then, the ventral side was dissected with a pair of scissors so that the whole heart was exposed. N ext, the distance between the tip of the snout to the base and apex of the heart was measured. The average of the distance between the base and apex from the snout was considered as the heart place (including 6
(HPA). Subsequently,
the sex was detected by dissecting genital area. In order to compare the HPA in the species of our research, and also to compare them with findings of previous studies, we reported HPA relative to TOL ( HT = HPA / TOL % ) . I n addition, we reported percentage of TAL relative to TOL (TT=TAL/TOL%). Thus, we compared HPA ( both absolute HPA and relative HT) , TAL ( both absolute TAL and relative TT) and their correlations with TOL, SVL and BM within the specimens of the current study, and in comparison with former studies. We used KolmogorovSmirnov test to assess normality of our dataset. As the dataset had normal distribution, the results were analyzed using S tudent’s t test, and statistical significance was considered when P≤0.05 and P≤0.01. Keeping procedure was based on Institutional Rules and Regulations for Keeping Laboratory Animals in Pasteur Institute of Iran. In the present research no euthanasia was performed whatsoever. 3. Results In regard to sexual differences in N. oxiana, Table 1 indicates that TOL and SVL in males were longer than females. Also, males indicated longer tails than females, and the tail constituted more proportion of body in males. Absolute HPA was significantly anterior in females than males (P 0 . 01 ) . A dditionally, TT in both groups had an insignificant negative correlation with SVL and BM (P>0.01), and a significant positive correlation with TAL(P0.01).
4.2. Correlations
With respect to sexual differences, our findings evinced that TOL, TAL, and SVL in males were more than females, in both groups N. oxiana and M. lebetina (P>0.05). Also, more TT in males indicated that tail constituted more proportion of the body length in them than females. In addition, whereas males had more BM in N. oxiana, females were slightly heavier than males in M. lebetina. Some studies have reported that males of species in which male-male combat has been recorded, tend to grow more than females. M oreover, male-male combat has been reported in both N. oxiana and M. lebetina[14,16]. Other studies have also indicated that tail in males is typically longer than females, which may stem from the need for enough space for hemipenes, and/or a device for wrestling over mating competition[16,20,26,38]. In accordance with the present results, tail in N. oxiana was significantly longer than that of M. lebetina. Also, whereas the difference of TAL in M. lebetina between males and females was statically significant (P0.05). This is consistent with Goldsmith explaining that in species with short TALs, sexual dimorphism in TAL is more evident[39].
There was a significant positive correlation between HPA
and each of TOL, SVL, and BM (P0.01). Also, in the present research HPA had a negative correlation with TAL in N. oxiana, while it had a positive correlation in M. lebetina (both species P>0.01). Moreover, in both species, HPA and HT both had negative correlation with TT (P>0.01). This slightly indicates that in these two species, the longer the tail constitutes the body length, the more forward the heart is located. I n this respect, B adeer proposed that the position of heart may be related to the location of the hydrostatic indifferent point (HIP, or zero pressure point) and its effect on the filling of the heart, because an upper HIP provides the heart with positive pressure and adequate blood filling[37]. Badeer also described that HIP in arboreal
4.3. Sexual differences
Alireza Nasoori et al./Asian Pac J Trop Med 2014; 7(Suppl 1): S137-S142
In this study, relative SVL to body length in females
was slightly more than males, approximately 84.23% and 83.36% in N. oxiana, and 88.9% and 88.12% in M. lebetina, respectively. Similarly, King proposed that females because of the need for reproductive space typically have larger SVL[30]. HPA variety between males and females has hardly ever been reported in snakes. The findings of the current study, however, for the first time showed that HPA, either absolute or relative, in females was located anterior compared to males in both N. oxiana and M. lebetina. Even though SVL constituted more proportion of the body in females than males, the heart location in females was anterior compared to males in the current study. Given the cardiac displacement in snakes on the one hand[11,40], and the more massive visceral organs in females than males[20], on the other hand, it is likely to justify the anterior HPA in females. It is noteworthy that an anterior heart has some downsides such as problems in venous return, because the heart would be farther than posterior part of the body. This problem can be obviated by long tail associated with tight integument, and more peripheral resistance[1,4,5]. Hence, we can suggest that in an identical situation such as similar body length and mass, between a male and female of the same species, since the female has shorter tail, and closer heart to head, compared to the male, and also considering cardiac displacement in snakes[11,40], the female is more vulnerable to hemodynamic disturbances resulting from gravitational alterations particularly in case of distention in visceral organs such as gravidity. Nevertheless, regarding HPA (but not TAL), Seymour believes that although the differences are statistically significant, since in snakes each centimeter difference in blood column formed above the heart only causes 0.77 mmHg blood pressure, the differences of the present research are biologically very small (R.S. Seymour, pers. comm). However, almost no study has so far regarded the differences between males and females in terms of ophidian cardiovascular responses to head-up tilt. Also, the studies have hardly ever grouped the snakes cardiovascular morphology based upon their sex. T hus, regarding the sexual differences reported in the present work, it is suggested that in ophidian cardiovascular studies, the animals be categorized based on their sex. Nevertheless, further investigations are required to assess the variation of feedback to head-up posture between male and female snakes. Because HPA and TAL along with their relationship to the other biometrics in N. oxiana were to a great extent consistent with typical terrestrial snakes, we can conclude that more important mechanisms are needed to aid cobra
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to conquer circulatory disturbances while head raising behavior. Also, the current study showed that females of N. oxiana and M. lebetina had shorter heart-head distance and TAL than males. Thus, it is inferred that such features along with cardiac displacement in snakes probably make females more vulnerable to up-right posture especially in case of visceral organs distention such as gravidity. In addition, it is suggested that in ophidian cardiovascular studies the samples be grouped based on their sex. Conflict of interest statement We declare that we have no conflict of interest. Acknowledgements We would like to express our heartfelt appreciation to Professor R. S. Seymour for his kind and valuable comments and discussions. Also, we are thankful to Dr. G. Gartner for providing us with his experimental data. The authors acknowledge that Mr. A. Lotfi closely collaborated with this investigation. This study was supported by the Pasteur Institute of Iran (Grant No. 556).
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S137
Contents lists available at ScienceDirect
Asian Pacific Journal of Tropical Medicine journal homepage:www.elsevier.com/locate/apjtm
Document heading
doi: 10.1016/S1995-7645(14)60220-0
place and tail length evaluation in N aja oxiana, M acrovipera lebetina, and Montivipera latifii H eart
1*
Alireza Nasoori
, Ali Taghipour2, Delavar Shahbazzadeh1, Abdolhossein Aminirissehei3, Sharif Moghaddam4,5
Biotechnology Research Center, Department of Medical Biotechnology, Venom and Toxin Unit, Pasteur Institute of Iran, Tehran, Iran
1
Department of Clinical Sciences, Faculty of Veterinary Medicine, Islamic Azad University, Karaj Branch, Rajaee Shahr, Moazen Blvd., Karaj, Iran
2
Pasteur Institute of Iran, Production and Research Complex, Biotechnology Processes Developing Center, 25th km. Tehran-Karaj Hwy. Karaj, Iran
3
Discipline of Linguistics, the University of Adelaide, Australia
4
Department of English, Faculty of Sciences & Research, the I. Azad University, Tehran, Iran
5
ARTICLE INFO
ABSTRACT
Article history: Received 23 Apr 2014 Received in revised form 3 May 2014 Accepted 13 Jun 2014 Available online 27 Aug 2014
Objective: To evaluate a) heart place and tail length, b) their correlations with other biometrics, c) sexual differences in those features, in regard to cardiovascular system in a number of snakes from Iran, about which there is little information. Methods: We studied the fresh mortalities of snakes including 14 Naja oxiana (N. oxiana), 23 Macrovipera lebetina, and one male Montivipera latifii acquired from the Serpentatium of Pasteur Institute of Iran. In this respect, each specimen first was weighted, and then its ventral side of the integument was incised, and heart place was measured. Subsequently, other biometrical features such as total length, TAL, and snout-vent length were measured. Results: The results showed that heart place in N. oxiana, Macrovipera lebetina and Montivipera latifii was about 18%, 32% and 30%, and also TAL constituted about 16%, 11% and 7% of total body length, respectively. Moreover, females indicated anterior heart place and shorter tail than males. Furthermore, the measures and correlations indicated few differences between N. oxiana and typical terrestrial species. Conclusions: The results denoted that in order to overcome hemocirculatory perturbations in vertical orientation while hooding and head raising behavior, N. oxiana need to have more important features than short heart to head distance and long tail. In addition, it gave the sexual differences in heart place and tail length between males and females. It is suggested that in ophidian cardiovascular studies the animals be grouped based upon their sex.
Keywords: Heart place Tail length Cardiovascular system Sexual differences Snake
1. Introduction Snakes have tubular and elongated bodies inside which cardiovascular system can be considered as a long fluidfilled tube[1,2]. T his morphology makes them liable to hemodynamic imbalances resulting from gravitational force changes such as things happen while climbing, or adopting vertical posture[1,3-5]. There are some anatomical *Corresponding author: Alireza Nasoori, Doctor of Veterinary Medicine (DVM), Biotechnology Research Center, Department of Medical Biotechnology, Venom and Toxin Unit, Pasteur Institute of Iran, Tehran, Iran. Tel: +982166480780, +989126957229 E-mail: [email protected], [email protected] Foundation Project: Supported by the Pasteur Institute of Iran (Grant No. 556).
traits with which the snakes can frequently experience gravitational alterations, such as shorter heart to head distance[1,5-7], and relatively long tail[2,6,8,9]. Previous studies have clearly shown that when snakes are tilted in head-up position, they undergo circulatory disturbances resulting from increased hydrostatic blood pressure due to blood column formation above their heart [3,5,6,10,11]. Therefore, head raising behavior of cobra, which is commonly known as terrestrial species[7,12], predisposes the snake to blood column formation above its heart. S o, cobra is expected to possess a number of features enabling it to overcome the hemodynamic perturbations. On the other hand, terrestrial vipers, in spite of being terrestrial, possess a number of morphological traits,
S138
Alireza Nasoori et al./Asian Pac J Trop Med 2014; 7(Suppl 1): S137-S142
such as low arterial pressure, tendency to suffer from passive blood congestion in hind part of the body, rather middle-located heart, long and vascularized trachea, and consequently lack of cardiovascular tolerance to upright posture, which are dissimilar to those of terrestrial species[1,5,7,10,13]. A number of former studies have already indicated sexual dimorphism in external features of ophidian body[14-19]. Nevertheless, to the best of our knowledge, few studies have focused on sexual differences in visceral organs[20,21], such as heart, and their possible effects on cardiovascular system. Therefore, we conducted the current research in order to study the biometrical features in Naja oxiana (N. oxiana), Macrovipera lebetina (M. lebetina) and Montivipera latifii ( M. latifii ) concerning heart to head distance and tail length ( TAL ) , and their correlations with each of total body length, snout-vent length and body mass (BM), in males and females, in order to evaluate their importance in cardiovascular system, about which there is little information. 2. Materials and methods I n this research, we studied 23 adult M. lebetina
( including 15
males and 8 females), 14 adult N. oxiana males and 8 females), and a male M. latifii, kept in the Serpentarium of Venom and Toxin Research L ab, P asteur I nstitute of I ran. T hey were all of I ran herpetofauna [22-25] . N. oxiana and M. lebetina were obtained from K horasan P rovinces, northeast of I ran, and M. latifii from T ehran P rovince, central parts of Iran. The snakes were fed with alive and dead rodents. T he specimens studied in our research were of fresh mortalities obtained from the S erpentarium. T hey all were studied on a table covered with plastic, and the measurements were carried out by the same person and the same measuring instruments. E ach specimen was weighed with a digital scale (A&D EK-1200 i NTEP Jewelry Buyer Scale, USA). Afterward, it was placed on the dorsal side on a piece of plastic on a table, and the distances from the tip of snout to vent (snout-vent length, SVL) and to tip of tail (total length, TOL) were accurately measured by a measuring tape, and noted down. Then, the ventral side was dissected with a pair of scissors so that the whole heart was exposed. N ext, the distance between the tip of the snout to the base and apex of the heart was measured. The average of the distance between the base and apex from the snout was considered as the heart place (including 6
(HPA). Subsequently,
the sex was detected by dissecting genital area. In order to compare the HPA in the species of our research, and also to compare them with findings of previous studies, we reported HPA relative to TOL ( HT = HPA / TOL % ) . I n addition, we reported percentage of TAL relative to TOL (TT=TAL/TOL%). Thus, we compared HPA ( both absolute HPA and relative HT) , TAL ( both absolute TAL and relative TT) and their correlations with TOL, SVL and BM within the specimens of the current study, and in comparison with former studies. We used KolmogorovSmirnov test to assess normality of our dataset. As the dataset had normal distribution, the results were analyzed using S tudent’s t test, and statistical significance was considered when P≤0.05 and P≤0.01. Keeping procedure was based on Institutional Rules and Regulations for Keeping Laboratory Animals in Pasteur Institute of Iran. In the present research no euthanasia was performed whatsoever. 3. Results In regard to sexual differences in N. oxiana, Table 1 indicates that TOL and SVL in males were longer than females. Also, males indicated longer tails than females, and the tail constituted more proportion of body in males. Absolute HPA was significantly anterior in females than males (P 0 . 01 ) . A dditionally, TT in both groups had an insignificant negative correlation with SVL and BM (P>0.01), and a significant positive correlation with TAL(P0.01).
4.2. Correlations
With respect to sexual differences, our findings evinced that TOL, TAL, and SVL in males were more than females, in both groups N. oxiana and M. lebetina (P>0.05). Also, more TT in males indicated that tail constituted more proportion of the body length in them than females. In addition, whereas males had more BM in N. oxiana, females were slightly heavier than males in M. lebetina. Some studies have reported that males of species in which male-male combat has been recorded, tend to grow more than females. M oreover, male-male combat has been reported in both N. oxiana and M. lebetina[14,16]. Other studies have also indicated that tail in males is typically longer than females, which may stem from the need for enough space for hemipenes, and/or a device for wrestling over mating competition[16,20,26,38]. In accordance with the present results, tail in N. oxiana was significantly longer than that of M. lebetina. Also, whereas the difference of TAL in M. lebetina between males and females was statically significant (P0.05). This is consistent with Goldsmith explaining that in species with short TALs, sexual dimorphism in TAL is more evident[39].
There was a significant positive correlation between HPA
and each of TOL, SVL, and BM (P0.01). Also, in the present research HPA had a negative correlation with TAL in N. oxiana, while it had a positive correlation in M. lebetina (both species P>0.01). Moreover, in both species, HPA and HT both had negative correlation with TT (P>0.01). This slightly indicates that in these two species, the longer the tail constitutes the body length, the more forward the heart is located. I n this respect, B adeer proposed that the position of heart may be related to the location of the hydrostatic indifferent point (HIP, or zero pressure point) and its effect on the filling of the heart, because an upper HIP provides the heart with positive pressure and adequate blood filling[37]. Badeer also described that HIP in arboreal
4.3. Sexual differences
Alireza Nasoori et al./Asian Pac J Trop Med 2014; 7(Suppl 1): S137-S142
In this study, relative SVL to body length in females
was slightly more than males, approximately 84.23% and 83.36% in N. oxiana, and 88.9% and 88.12% in M. lebetina, respectively. Similarly, King proposed that females because of the need for reproductive space typically have larger SVL[30]. HPA variety between males and females has hardly ever been reported in snakes. The findings of the current study, however, for the first time showed that HPA, either absolute or relative, in females was located anterior compared to males in both N. oxiana and M. lebetina. Even though SVL constituted more proportion of the body in females than males, the heart location in females was anterior compared to males in the current study. Given the cardiac displacement in snakes on the one hand[11,40], and the more massive visceral organs in females than males[20], on the other hand, it is likely to justify the anterior HPA in females. It is noteworthy that an anterior heart has some downsides such as problems in venous return, because the heart would be farther than posterior part of the body. This problem can be obviated by long tail associated with tight integument, and more peripheral resistance[1,4,5]. Hence, we can suggest that in an identical situation such as similar body length and mass, between a male and female of the same species, since the female has shorter tail, and closer heart to head, compared to the male, and also considering cardiac displacement in snakes[11,40], the female is more vulnerable to hemodynamic disturbances resulting from gravitational alterations particularly in case of distention in visceral organs such as gravidity. Nevertheless, regarding HPA (but not TAL), Seymour believes that although the differences are statistically significant, since in snakes each centimeter difference in blood column formed above the heart only causes 0.77 mmHg blood pressure, the differences of the present research are biologically very small (R.S. Seymour, pers. comm). However, almost no study has so far regarded the differences between males and females in terms of ophidian cardiovascular responses to head-up tilt. Also, the studies have hardly ever grouped the snakes cardiovascular morphology based upon their sex. T hus, regarding the sexual differences reported in the present work, it is suggested that in ophidian cardiovascular studies, the animals be categorized based on their sex. Nevertheless, further investigations are required to assess the variation of feedback to head-up posture between male and female snakes. Because HPA and TAL along with their relationship to the other biometrics in N. oxiana were to a great extent consistent with typical terrestrial snakes, we can conclude that more important mechanisms are needed to aid cobra
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to conquer circulatory disturbances while head raising behavior. Also, the current study showed that females of N. oxiana and M. lebetina had shorter heart-head distance and TAL than males. Thus, it is inferred that such features along with cardiac displacement in snakes probably make females more vulnerable to up-right posture especially in case of visceral organs distention such as gravidity. In addition, it is suggested that in ophidian cardiovascular studies the samples be grouped based on their sex. Conflict of interest statement We declare that we have no conflict of interest. Acknowledgements We would like to express our heartfelt appreciation to Professor R. S. Seymour for his kind and valuable comments and discussions. Also, we are thankful to Dr. G. Gartner for providing us with his experimental data. The authors acknowledge that Mr. A. Lotfi closely collaborated with this investigation. This study was supported by the Pasteur Institute of Iran (Grant No. 556).
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