Revisão taxonômica de Dipsas Laurentis, 1768 (Serpentes, Colubridae) de ocorrência na Mata Atlântica

The taxonomic revision of Dipsas from the Atlantic forest Is given based on morphological and hemipennial data as well as on geographical distribution. The involved species are: Dipsas albifrons (Sauvage, 1884), D. catesby (Sentzen, 1796), D. incerta (Jan, 1863), D. petersi Hoge & Romano, 1975, D. neivai Amaral, 1923 and Dipsas sp. The principal results obtained are: 1) Description of a new species of the indica group with occurrence in the southeast Brazil associated to semidecidual and decidual forests; 2) the realocation of D. indica bucephala (Shaw, 1802) in the sinonimy of D. indica indica Laurenti, 1768; 3) the elevation of D. indica petersi Hoge & Romano, 1975 to the species levei; 4) the redescription of Dipsas albifrons, D. catesby, D. incerta, D. petersi e D. neivai, with the extension of knowledge on meristic characters variation and on geographical distribution of the involved species; 5) confirmation of the presence of D. catesby (Sentzen, 1796) in the Atlantic forest; and 6) acquisition of knowledge on reproductive period of Dipsas albifrons, D. incerta, D. petersi e D. neivai e Dipsas sp., that revealed to be aseasonal, oviparous, and that the groups of eggs in oviducts range between 1-9.CAPESCom base em dados morfológicos, hemipenianos e de distribuição geográfica, é feita a revisão taxonômica das espécies de Dipsas que ocorrem na Mata Atlântica a saber: D. albifrons (Sauvage, 1884), D. catesby (Sentzen, 1796), D. incerta (Jan, 1863), D. indica petersi Hoge & Romano, 1975, D. neivai Amaral, 1923. e Dipsas sp. Entre os principais resultados alcançados destacam-se: 1) descrição de uma nova espécie do grupo indica com distribuição no sudeste brasileiro, associada a mata semidecidual e decidual; 2) a passagem de Dipsas indica bucephala (Shaw, 1802) para a sinonímia de D. indica indica Laurenti, 1768; 3) a elevação de D. indica petersi Hoge & Romano, 1975 à categoria de espécie; 4) a re-descrição de D. albifrons, D. incerta, D. petersi, e D. neivai, com ampliação dos conhecimentos sobre a variação dos caracteres merísticos, bem como a respeito da distribuição geográfica das espécies envolvidas neste estudo; 5) a confirmação da presença de D. catesby (Sentzen, 1796) na mata Atlântica e 6) D. albifrons, D. incerta. b. petersi, D. neivai e Dipsas sp. são ovíparas, se reproduzem ao longo de todo o ano com os grupos de ovos no oviduto ou folículos ovarianos variando de 1 a 9

The evolutionary implications of hemipenial morphology of rattlesnake Crotalus durissus terrificus (Laurent, 1768) (Serpentes: Viperidae: Crotalinae)

Most amniotes vertebrates have an intromittent organ to deliver semen. The reptile Sphenodon and most birds lost the ancestral penis and developed a cloaca-cloaca mating. Known as hemipenises, the copulatory organ of Squamata shows unique features between the amniotes intromittent organ. They are the only paired intromittent organs across amniotes and are fully inverted and encapsulated in the tail when not in use. The histology and ultrastructure of the hemipenes of Crotalus durissus rattlesnake is described as the evolutionary implications of the main features discussed. The organization of hemipenis of Crotalus durissus terrificus in two concentric corpora cavernosa is similar to other Squamata but differ markedly from the organization of the penis found in crocodilians, testudinata, birds and mammals. Based on the available data, the penis of the ancestral amniotes was made of connective tissue and the incorporation of smooth muscle in the framework of the sinusoids occurred independently in mammals and Crotalus durissus. The propulsor action of the muscle retractor penis basalis was confirmed and therefore the named should be changed to musculus hemipenis propulsor.The retractor penis magnus found in Squamata has no homology to the retractor penis of mammals, although both are responsible for the retraction of the copulatory organFAPESP, Fundação de Amparo a Pesquisa do Estado de Sao Paulo, #2011/11828-4CNP

Role Of A Novel Tetrodotoxin-resistant Sodium Channel In The Nitrergic Relaxation Of Corpus Cavernosum From The South American Rattlesnake Crotalus Durissus Terrificus.

Coitus in snakes may last up to 28 hours; however, the mechanisms involved are unknown. To evaluate the relevance of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-phosphodiesterase type 5 (PDE5) system in snake corpus cavernosum reactivity. Hemipenes were removed from anesthetized South American rattlesnakes (Crotalus durissus terrificus) and studied by light and scanning electronic microscopy. Isolated Crotalus corpora cavernosa (CCC) were dissected from the non-spiny region of the hemipenises, and tissue reactivity was assessed in organ baths. Cumulative concentration-response curves were constructed for acetylcholine (ACh), sodium nitroprusside (SNP), 5-cyclopropyl-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-yl]pyrimidin-4-ylamine (BAY 41-2272), and tadalafil in CCC precontracted with phenylephrine. Relaxation induced by electrical field stimulation (EFS) was also done in the absence and presence of N(ω) nitro-L-arginine methyl ester (L-NAME; 100 µM), 1H-[1, 2, 4] oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 µM) and tetrodotoxin (TTX; 1 µM). The hemipenes consisted of two functionally concentric corpora cavernosa, one of them containing radiating bundles of smooth muscle fibers (confirmed by α-actin immunostaining). Endothelial and neural nitric oxide synthases were present in the endothelium and neural structures, respectively; whereas soluble guanylate cyclase and PDE5 were expressed in trabecular smooth muscle. ACh and SNP relaxed isolated CCC, with the relaxations being markedly reduced by L-NAME and ODQ, respectively. BAY 41-2272 and tadalafil caused sustained relaxations with potency (pEC(50) ) values of 5.84 ± 0.17 and 5.10 ± 0.08 (N=3-4), respectively. In precontracted CCC, EFS caused frequency-dependent relaxations that lasted three times longer than those in mammalian CC. Although these relaxations were almost abolished by either L-NAME or ODQ, they were unaffected by TTX. In contrast, EFS-induced relaxations in marmoset CC were abolished by TTX. Rattlesnake CC relaxation is mediated by the NO-cGMP-PDE5 pathway in a manner similar to mammals. The novel TTX-resistant Na channel identified here may be responsible for the slow response of smooth muscle following nerve stimulation and could explain the extraordinary duration of snake coitus.81616-2

Role of a Novel Tetrodotoxin-Resistant Sodium Channel in the Nitrergic Relaxation of Corpus Cavernosum from the South American Rattlesnake Crotalus Durissus Terrificus

Introduction. Coitus in snakes may last up to 28 hours; however, the mechanisms involved are unknown. Aim. To evaluate the relevance of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-phosphodiesterase type 5 (PDE5) system in snake corpus cavernosum reactivity. Methods. Hemipenes were removed from anesthetized South American rattlesnakes (Crotalus durissus terrificus) and studied by light and scanning electronic microscopy. Isolated Crotalus corpora cavernosa (CCC) were dissected from the non-spiny region of the hemipenises, and tissue reactivity was assessed in organ baths. Main Outcome Measures. Cumulative concentration-response curves were constructed for acetylcholine (ACh), sodium nitroprusside (SNP), 5-cyclopropyl-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-yl]pyrimidin-4-ylamine (BAY 41-2272), and tadalafil in CCC precontracted with phenylephrine. Relaxation induced by electrical field stimulation (EFS) was also done in the absence and presence of N omega nitro-L-arginine methyl ester (L-NAME; 100 mu M), 1H-[1, 2, 4] oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 mu M) and tetrodotoxin (TTX; 1 mu M). Results. The hemipenes consisted of two functionally concentric corpora cavernosa, one of them containing radiating bundles of smooth muscle fibers (confirmed by alpha-actin immunostaining). Endothelial and neural nitric oxide synthases were present in the endothelium and neural structures, respectively; whereas soluble guanylate cyclase and PDE5 were expressed in trabecular smooth muscle. ACh and SNP relaxed isolated CCC, with the relaxations being markedly reduced by L-NAME and ODQ, respectively. BAY 41-2272 and tadalafil caused sustained relaxations with potency (pEC(50)) values of 5.84 +/- 0.17 and 5.10 +/- 0.08 (N = 3-4), respectively. In precontracted CCC, EFS caused frequency-dependent relaxations that lasted three times longer than those in mammalian CC. Although these relaxations were almost abolished by either L-NAME or ODQ, they were unaffected by TTX. In contrast, EFS-induced relaxations in marmoset CC were abolished by TTX. Conclusions. Rattlesnake CC relaxation is mediated by the NO-cGMP-PDE5 pathway in a manner similar to mammals. The novel TTX-resistant Na channel identified here may be responsible for the slow response of smooth muscle following nerve stimulation and could explain the extraordinary duration of snake coitus. Capel RO, Monica FZ, Porto M, Barillas S, Muscara MN, Teixeira SA, Arruda AMM, Pissinatti, L, Pissinatti A, Schenka AA, Antunes E, Nahoum C, Cogo JC, de Oliveira MA, and De Nucci G. Role of a novel tetrodotoxin-resistant sodium channel in the nitrergic relaxation of corpus cavernosum from the South American rattlesnake Crotalus durissus terrificus. J Sex Med 2011;8:1616-1625

Scanning electron microscopy of the trunk region of hemipenis of<i>Crotalus durissus terrificus</i>.

<p>A: Wide view of the trunk showing two cavernous bodies, one internal (CCI) and another external (CCE), near the <i>sulcus spermaticus</i> (arrowhead); the <i>musculus retractor penis magnus</i> (MRM.), spines rounding the trunk (**) and is observed that the number of <i>trabecula</i> is greater in CCE than in CCE. B: Detail of external surface of hemipenis in an area without spines, the epithelial cells (EC) covering the <i>tunica albuginea</i> (TA) of external face of hemipenis are observed. C: Detail of layers of connective tissue under epithelial cells presented in B. The connective tissue presented is non-cornified and is composed of two-to-five layers. D and E: Detail of insertion point of spine (*) in CCE in the trunk region, arrows point to smooth muscle bundles that anchor the spine in hemipenis.</p

Macroscopic view of the hemipenis of<i>Crotalus durissus terrificus</i>.

<p>A: Everted hemipenis, B. inverted hemipenis. <i>musculus retractor penis magnus</i> (MRM), black arrow points to artery and white arrow points to veins.</p

Scanning electron microscopy of the apex region of hemipenis of<i>Crotalus durissus terrificus</i>.

<p>A: Wide view of the transversal cut from apex region of hemipenis, it is possible to see two cavernous bodies, one internal (CCI) and another external (CCE.), and the <i>musculus retractor penis magnus</i> (MRM), arrows point to external and internal sphincters. B: Detail of <i>sulcus spermaticus</i> (SS) and CCE, delimited by external (white arrow) and internal (black arrow) sphincters. The <i>trabeculas</i> (*) delimit the lacunar space. C: Detail of net formed by smooth muscle bundles (<i>trabeculas</i>), arrows point to cluster of erythrocytes rested in bundles. D: Detail of central sinusoid (CS), arrow points to transversal sinusoids inside the muscle. E: Detail of lacunar spaces (LA), with different sizes, presents in external sphincter and in epithelial surface.</p

Light microscopy of hemipenis from<i>Crotalus durissus terrificus.</i>

<p>A: Transversal cut of <i>musculus retractor penis magnus</i> showing muscles cells (MC) and the central sinusoid (CS). B: Detail of central sinusoid in a transversal cut of <i>musculus retractor penis magnus.</i> The central sinusoid (CS) is layered by smooth muscle cells (MC) and a endothelium, erythrocytes (arrow) are observed inside the sinusoid. C: Detail of <i>corpus cavernosum</i> internal, smooth muscle cells (SM); surrounding lacunar spaces (LA). D: Detail of a <i>trabecula</i>, the connective tissue (CT) are surrounded by smooth muscle cells (*) and endothelial cells (arrow) forming lacunar spaces (LA).</p

Macroscopic view of the hemipenis of<i>Crotalus durissus terrificus</i> partially everted.

<p>In A and B it is possible to observed the stretched <i>m. retractor penis basalis</i> (arrow) contouring the pedicle of the hemipenis, and participating in <i>sulcus spermaticus</i> fold (arrowhead). In C and D it is possible to observes the dissected muscle (arrow) and its loop shape.</p