A new locality of Late Cretaceous snakes, mammals and other vertebrates in Africa (western Libya)

s sp. nov. (Reptilia sp. nov. (Reptilia, Serpentes, Simoliopheidae) is described from the Upper Cretaceous ‘unnamed’ beds of the Mizdah Formation (Santonian-Campanian) at Draa Ubari in western Libya. The accompanying fauna consists of an undetermined mammal represented by a caudal vertebra, of hybodontoid, ganopristid and lamnoid sharks, as well as dipnoans, lepisosteids, pycnodonts, enchodontids, turtles, crocodiles and ?dinosaurs.

Résumé

Une nouvelle localité de serpents, mammifères et autres vertébrés du Crétacé supérieur en Afrique (Libye occidentale). s sp. nov. (Reptilia sp. nov. (Reptilia, Serpentes, Simoliopheidae) est décrit dans des grès de la formation Mizdah (Santonien-Campanien), à Draa Ubari en Libye occidentale. Les mêmes couches ont livré une vertèbre caudale de mammifère indéterminé, ainsi que des restes de requins hybodontoïdes, ganopristidés et lamnoïdes, de dipneustes, lépisostéïdes, pycnodontes, enchodontidés, tortues, crocodiles et? dinosaures.     

Cloning and sequence analysis of the cDNA encoding a snake neurotoxin precursor

A recombinant plasmid has been constructed containing a sequence of 186 nucleotides encoding a potent neurotoxin found in the venom of the sea-snake Laticauda semifasciata and designated as erabutoxin a. This sequence is flanked, in the upstream region, by a sequence of 60 nucleotides encoding a hydrophobic peptide fragment presumably involved in the secretion process of the neurotoxin. The sequence coding for the toxin ends with a termination codon which is followed by a 3'-untranslated sequence of approximately 240 nucleotides (excluding the poly(A) tract).     

蛇瓜芽的诱导

蛇瓜的茎尖和腋芽以MS分别加入0.5～2.0 mg*L-1的6-BA和0.5～1.0 mg*L-1的6-BA与不同浓度的2,4-D、NAA、IAA组合培养时,以1.0 mg*L-1的6-BA以及6-BA与0.1～1.0 mg*L-1的IAA组合对芽的诱导效果最好.     

Isolation and characterization of the alpha and beta subunits of the platelet-activating glycoprotein from the venom of Crotalus durissus cascavella

It was concluded in a previous paper that the high Mr platelet-activating glycoprotein isolated earlier from the venom of Crotalus durissus cascavella has an hexameric structure of the alpha 3 beta 3 type involving two distinct subunits. Data reported here demonstrate that these two subunits are separable from each other by ion exchange chromatography under denaturating conditions, have similar Mrs (alpha = 12,540 et beta = 13,770) and exist in a one to one ratio within the native molecule. Carbohydrate analysis indicated that they are both similarly glycosylated to a small extent. They have slightly different amino-acid compositions, a common N-terminal sequence up to the fifth residue and similar extinction coefficients at 280 nm. The native molecule has a calculated Mr of 78,930. Additional data demonstrated that convulxin from the venom of Crotalus durissus terrificus is the same platelet-activating agent as the presently described platelet-activating glycoprotein (PAG) from the venom of Crotalus durissus cascavella.     

Degeneration patterns of the olfactory receptor genes in sea snakes

The sense of smell relies on the diversity of olfactory receptor (OR) repertoires in vertebrates. It has been hypothesized that different types of ORs are required in terrestrial and marine environments. Here we show that viviparous sea snakes, which do not rely on a terrestrial environment, have significantly lost ORs compared with their terrestrial relatives, supporting the hypothesis. On the other hand, oviparous sea snakes, which rely on a terrestrial environment for laying eggs, still maintain their ORs, reflecting the importance of the terrestrial environment for them. Furthermore, we found one Colubroidea snake (including sea snakes and their terrestrial relatives)‐specific OR subfamily which had diverged widely during snake evolution after the blind snake–Colubroidea snake split. Interestingly, no pseudogenes are included in this subfamily in sea snakes, and this subfamily seems to have been expanding rapidly even in an underwater environment. These findings suggest that the Colubroidea‐specific ORs detect nonvolatile odorants.