Faunal diversity of Paederus Fabricius, 1775 (Coleoptera: Staphylinidae) in Iran

Beetles of the genus Paederus sensu stricto Fabricius, 1775 (Coleoptera: Staphylinidae) are often noticed because of their potency in inducing a dermal lesion, so-called linear dermatitis. This genus, which is placed in the tribe Paederini and subfamily Paederinae of Staphylinidae, currently comprises 490 species worldwide. Our study presents a short review of the former records of Paederus spp. in Iran plus some unpublished data. Field collections were done during March-October yearly (1997-2007) in northern and southern Iran and April-June from central, eastern, western and north-western Iran (2008-2009). The present study adds four species to the Iranian fauna of the genus Paederus, which are P. brevipennis Lacordaire, 1835, P. basalis Bernhauer, 1914, P. pubescens Cameron, 1914 and P. schoenherri Czwalina, 1899. Paederus brevipennis and P. schoenherri are the first members of the subgenus Harpopaederus Scheerpeltz, 1957, ever reported from Iran. Considering previous reports, museum-deposited materials and our findings, 14 species and subspecies of the genus Paederus, which are grouped in five subgenera, occur in Iran. These subgenera are Eopaederus Scheerpeltz, Harpopaederus Scheerpeltz, Heteropaederus Scheerpeltz, Paederus Fabricius and Poederomorphus des Cottes; however P. duplex spectabilis Bernhauer, 1913 is not yet attributed to any of the 13 so-far defined subgenera

Extreme bendability of DNA double helix due to bending asymmetry

Experimental data of the DNA cyclization (J-factor) at short length scales, as a way to study the elastic behavior of tightly bent DNA, exceed the theoretical expectation based on the wormlike chain (WLC) model by several orders of magnitude. Here, we propose that asymmetric bending rigidity of the double helix in the groove direction can be responsible for extreme bendability of DNA at short length scales and it also facilitates DNA loop formation at these lengths. To account for the bending asymmetry, we consider the asymmetric elastic rod (AER) model which has been introduced and parametrized in an earlier study (B. Eslami-Mossallam and M. Ejtehadi, Phys. Rev. E 80, 011919 (2009)). Exploiting a coarse grained representation of DNA molecule at base pair (bp) level, and using the Monte Carlo simulation method in combination with the umbrella sampling technique, we calculate the loop formation probability of DNA in the AER model. We show that, for DNA molecule has a larger J-factor compared to the WLC model which is in excellent agreement with recent experimental data.Comment: 8 pages, 9 figure