No abstract

The complete mitochondrial genome was obtained from a microchiropteran bat, Artibeus jamaicensis. The presumptive amino acid sequence for the protein-coding genes was compared with predicted amino acid sequences from several representatives of other mammalian orders. Data were analyzed using maximum parsimony, maximum likelihood, and neighbor joining. All analyses placed bats as the sister group of carnivores, perissodactyls, artiodactyls, and cetaceans (e.g., 100% bootstrap value with both maximum parsimony and neighbor joining). The data strongly support a new hypothesis about the origin of bats, specifically a bat/ferungulate grouping. None of the analyses supported the superorder Archonta (bats, flying lemurs, primates, and tree shrews). Our hypothesis regarding the relationship of bats to other eutherian mammals is concordant with previous molecular studies and contrasts with hypotheses based solely on morphological criteria and an incomplete fossil record. The A. jamaicensis mitochondrial DNA control region has a complex pattern of tandem repeats that differs from previously reported chiropteran control regions.

The NF-B/Rel family of mammalian transcription factors represents a focal point for understanding how extracellular signals induce the expression of specific genes, which are involved in processes as diverse as cell division, inflammation, and apoptosis (programmed cell death) (3-5, 18, 31, 47, 49, 50). The Rel protein family can be classified into two structurally related groups. The first consists of p50 and p52, the products of the NF-B1 and NF-B2 genes, respectively (48). These proteins contain a 300-amino-acid sequence known as the Rel homology domain, which contains the information required for dimerization, nuclear translocation, and DNA binding (2, 42). The second group of Rel proteins includes RelA (p65), RelB, and c-Rel (the cellular homologue to the product of the v-Rel oncogene, isolated from the reticuloendotheliosis virus) (18). In addition to a Rel homology domain, these proteins have a transcriptional transactivation domain and form homo-and heterodimers with p50 and p52. The most common form of NF-B is a heterodimer composed of p50 and RelA subunits.NF-B is anchored in the cytoplasm of most nonstimulated cells by a noncovalent interaction with an inhibitory protein, IB (1). The principal IB-like proteins are IB␣, -␤, and -ε (3, 17). Additionally, the p105 and p100 products of the NF-B1 and NF-B2 genes can exert inhibitory effects on 48). Exposure of cells to proinflammatory cytokines, such as tumor necrosis factor alpha (TNF-␣) or interleukin-1 (IL-1), promotes the dissociation of IB from NF-B, unmasking the NF-B nuclear localization signal, thereby allowing its nuclear translocation to upregulate specific gene expression (3, 48). The ability of TNF receptors to induce NF-B activation requires the serine-threonine kinase RIP (receptor-interacting protein) (21) and adapter proteins belonging to the TRAF (TNF-receptor-associated factor) family (39), which lack enzymatic activity and share sequence homology at their C-terminal receptor-binding regions. In transfection studies, TRAF2 and RIP may mediate the activation of NF-B in response to TNF-␣, whereas TRAF6, MyD88, and IRAK are required for activation of NF-B in response to 8,13,34,51). However, studies using cells derived from RIP and TRAF2 knockout (KO) mice have shown that RIP is essential for NF-B induction whereas TRAF2 is required for c-Jun Nterminal kinase (JNK) activation by 24,54).