Bacteriophage T4 gene 41 helicase and gene 59 helicase-loading protein: A versatile couple with roles in replication and recombination

Bacteriophage T4 uses two modes of replication initiation: origin-dependent replication early in infection and recombination-dependent replication at later times. The same relatively simple complex of T4 replication proteins is responsible for both modes of DNA synthesis. Thus the mechanism for loading the T4 41 helicase must be versatile enough to allow it to be loaded on R loops created by transcription at several origins, on D loops created by recombination, and on stalled replication forks. T4 59 helicase-loading protein is a small, basic, almost completely α-helical protein whose N-terminal domain has structural similarity to high mobility group family proteins. In this paper we review recent evidence that 59 protein recognizes specific structures rather than specific sequences. It binds and loads the helicase on replication forks and on three- and four-stranded (Holliday junction) recombination structures, without sequence specificity. We summarize our experiments showing that purified T4 enzymes catalyze complete unidirectional replication of a plasmid containing the T4 ori(uvsY) origin, with a preformed R loop at the position of the R loop identified at this origin in vivo. This replication depends on the 41 helicase and is strongly stimulated by 59 protein. Moreover, the helicase-loading protein helps to coordinate leading and lagging strand synthesis by blocking replication on the ori(uvsY) R loop plasmid until the helicase is loaded. The T4 enzymes also can replicate plasmids with R loops that do not have a T4 origin sequence, but only if the R loops are within an easily unwound DNA sequence.

BigLaw Identity Capital: Pink and Blue, Black and White

This Article advances a new capital framework for understanding the bargain between large law firms and their lawyers, depicting BigLaw relationships not as basic labor-salary exchanges but rather as complex transactions in which large law firms and their lawyers exchange labor and various forms of capital — social, cultural, and identity. First, it builds on the work of Pierre Bourdieu regarding economic, cultural, symbolic, and social capital by examining the concepts of positive and negative capital, exploring the meaning of capital ownership by entities, and developing the notion of identity capital — the value individuals and institutions derive from their identities. Then, the Article advances a capital theory of BigLaw, in which large law firms and their lawyers engage in complex transactions trading labor, social, cultural, and identity capital for economic, social, cultural, and identity capital. Capital analysis sheds new light on the well-documented and troubling underrepresentation of diverse lawyers at BigLaw. It shows that the underrepresentation of women and minority lawyers is not solely the result of exogenous forces outside the control of large law firms such as implicit bias, but rather the outcome of the very exchanges in which BigLaw and its lawyers engage. Specifically, large law firms take into account the capital endowments of their lawyers in making hiring, retention and promotion decisions, and derive value from their lawyers’ capital, for example, by trading on the identity of women and minority lawyers in marketing themselves as being diverse and inclusive to clients and potential recruits. Yet, while BigLaw trades for the identity capital of women and minority lawyers, it fails to offer them opportunities in return to acquire the social and cultural capital necessary for attaining positions of power, resulting in underrepresentation. Moreover, these labor-capital exchanges are often implicit and made by uninformed participants, and therefore unjust. Exactly because the capital framework describes the underrepresentation of diverse lawyers at BigLaw as an endogenous outcome within the control of BigLaw and its lawyers, however, it is a cautiously optimistic model that offers hope for greater representation of diverse lawyers in positions of power and influence. The Article suggests policies and procedures BigLaw can and should adopt to improve the quality of the exchanges it offers to women and minority attorneys and to reduce the underrepresentation of diverse lawyers within its ranks. Employing the concepts of capital transparency, capital boundary, and capital infrastructure, it demonstrates how BigLaw can (1) explicitly recognize the roles social, cultural, and identity capital play in its hiring, retention and promotion apparatuses and (2) revise its policies and procedures to ensure that all of its lawyers have equal opportunities to develop the requisite capital and compete on equal and fair terms for positions of power and influence.

Mechanical, thermal and colorimetric properties of LLDPE coloured with a blue nanopigment and conventional blue pigments

Purpose – This research deals with a new kind of nanopigment, obtained from the combination of organic dyes and layered nanoclays, that the authors call nanoclay-colorant pigment (NCP). Whilst they have already been employed in inks and coatings, to date these nanopigments have not been used as pigments for polymers. The existing lack of knowledge surrounding them must be redressed in order to bridge the gap between current academic studies and commercial exploitation. Therefore, the main purpose of this paper is to examine the hitherto unknown aspects of the NCP, which relate specifically to their applicability as a new type of colorant for polymers. Design/methodology/approach – A blue NCP has been prepared at the laboratory according to the patented method of synthesis (patent WO0104216), using methylene blue and montmorillonite nanoclay. It has then been applied to a thermoplastic polymer (linear low-density polyethylene – LLDPE) to obtain a coloured sample. Furthermore, samples with the same polymer but using conventional blue colorants have been prepared under the same processing conditions. The mechanical, thermal and colorimetric properties of these materials have been compared. Findings – The thermal stability of the sample coloured with NCP is reduced to some extent, while the mechanical strength is slightly increased. Moreover, this sample has better colour performance than the conventionally pigmented samples. Originality/value – In this paper, a blue NCP has been synthesised and successfully employed with polyethylene and the obtained sample shows better colour performance than polyethylene with conventional pigments.