Genetic variability of indigenous cowpea genotypes as determined using inter-simple sequence repeats markers

Cowpea [Vigna unguiculata (L.) Walp.] is cultivated widely by small farmers in the semiarid region of Northeastern Brazil for subsistence purposes, especially to complement the family income. However, owing to the limited availability of water in this region, there is an urgent need for novel highly productive drought-tolerant cultivars. The aim of the present study was to establish the genetic variability of 14 cowpea populations (60 indigenous genotypes from 13 microregions of Rio Grande do Norte and 4 domesticated cultivars produced by Embrapa) using inter-simple sequence repeats (ISSR) markers. The set of 13 selected primers generated a total of 257 loci, 247 (96.11%) of which were polymorphic, with sizes ranging between 200 and 2000 bp. Genetic similarities between accessions were estimated from Jaccard coefficients and genetic relationships were determined from the dendrogram constructed using the unweighted pair group method with arithmetic average (UPGMA) technique. Bayesian statistics  coupled with the Markov chain Monte Carlo technique was applied to determine population structure, while the genetic variability was established by analysis of molecular variance. UPGMA analysis allowed the separation of the genotypes into three groups, but no relationship between the genetic and  geographical distances was observed. The fixation index was considered intermediary (FST = 0.0818), the average heterozygosity was low (HS = 0.39) and the coefficient of endogamy was high (f = 92.6%). The results show the presence of genetic diversity among the studied populations and revealed that such variability could be attributed mainly to intra-population variability (91.82%).Key words: Vigna unguiculata, genetic diversity, plant improvement, drought stress

Continuous Group Key Agreement with Active Security

A continuous group key agreement (CGKA) protocol allows a long-lived group of parties to agree on a continuous stream of fresh secret key material. The protocol must support constantly changing group membership, make no assumptions about when, if, or for how long members come online, nor rely on any trusted group managers. Due to sessions\u27 long life-time, CGKA protocols must simultaneously ensure both post-compromise security and forward secrecy (PCFS). That is, current key material should be secure despite both past and future compromises. The work of Alwen et al. (CRYPTO\u2720), introduced the CGKA primitive and identified it as a crucial component for constructing end-to-end secure group messaging protocols (SGM) (though we believe there are certainly more applications given the fundamental nature of key agreement). The authors analyzed the TreeKEM CGKA, which lies at the heart of the SGM protocol under development by the IETF working group on Messaging Layer Security (MLS). In this work, we continue the study of CGKA as a stand-alone cryptographic primitive. We present $3$ new security notions with increasingly powerful adversaries. Even the weakest of the 3 (passive security) already permits attacks to which all prior constructions (including all variants of TreeKEM) are vulnerable. Going further, the 2 stronger (active security) notions additionally allow the adversary to use parties\u27 exposed states (and full network control) to mount attacks. These are closely related to so-called insider attacks, which involve malicious group members actively deviating from the protocol. Insider attacks present a significant challenge in the study of CGKA (and SGM). Indeed, we believe ours to be the first security notions (and constructions) to formulate meaningful guarantees (e.g. PCFS) against such powerful adversaries. They are also the first composable security notions for CGKA of any type at all. In terms of constructions, for each of the 3 security notions we provide a new CGKA scheme enjoying sub-linear (potentially even logarithmic) communication complexity in the number of group members. We prove each scheme optimally secure, in the sense that the only security violations possible are those necessarily implied by correctness

Factors associated to infection by Toxoplasma gondii in pregnant women attended in Basic Health Units in the city of Rolândia, Paraná, Brazil

The aim of the present work was to determine the prevalence of IgG and IgM anti-Toxoplasma gondii antibodies and the factors associated to the infection in pregnant women attended in Basic Health Units in Rolândia, Paraná, Brazil. The sample was divided in two groups: group I (320 pregnant women who were analyzed from July 2007 to February 2008) and group II (287 pregnant women who were analyzed from March to October 2008). In group I, it was found 53.1% of pregnant women with IgG reactive and IgM non-reactive, 1.9% with IgG and IgM reactive, 0.3% with IgG non-reactive and IgM reactive and 44.7% with IgG and IgM non-reactive. In group II, it was found 55.1% with IgG reactive and IgM non-reactive and 44.9% with IgG and IgM non-reactive. The variables associated to the presence of IgG antibodies were: residence in rural areas, pregnant women between 35-40 years old, low educational level, low family income, more than one pregnancy, drinking water which does not originate from the public water supply system and the habit of handling soil or sand. Guidance on primary prevention measures and the quarterly serological monitoring of the pregnant women in the risk group are important measures to prevent congenital toxoplasmosis