Light capture and pigment diversity in marine and freshwater cryptophytes

Phenotypic traits associated with light capture and phylogenetic relationships were characterized in 34 strains of diversely pigmented marine and freshwater cryptophytes. Nuclear SSU and partial LSU rDNA sequence data from 33 of these strains plus an additional 66 strains produced a concatenated rooted maximum likelihood tree that classified the strains into 7 distinct clades. Molecular and phenotypic data together support: (i) the reclassification of Cryptomonas irregularis NIES 698 to the genus Rhodomonas, (ii) revision of phycobiliprotein (PBP) diversity within the genus Hemiselmis to include cryptophyte phycocyanin (Cr‐PC) 569, (iii) the inclusion of previously unidentified strain CCMP 2293 into the genus Falcomonas, even though it contains cryptophyte phycoerythrin 545 (Cr‐PE 545), and (iv) the inclusion of previously unidentified strain CCMP 3175, which contains Cr‐PE 545, in a clade with PC‐containing Chroomonas species. A discriminant analysis‐based model of group membership correctly predicted 70.6% of the clades using three traits: PBP concentration · cell^?1, the wavelength of PBP maximal absorption, and habitat. Non‐PBP pigments (alloxanthin, chl‐a, chl‐c₂, α‐carotene) did not contribute significantly to group classification, indicating the potential plasticity of these pigments and the evolutionary conservation of the PBPs. Pigment data showed evidence of trade‐offs in investments in PBPs vs. chlorophylls (a +c₂).     

Use of behavioral measures to assess reproductive status in maned wolves (Chrysocyon brachyurus)

Captive breeding efforts of the threatened maned wolf (Chrysocyon brachyurus) have been plagued by a lack of reliable reproduction and a high rate of neonatal mortality. A particular problem for animal managers has been the ability to detect pregnancy in a noninvasive manner. Pseudopregnancies are common, and many staff hours are expended preparing for a birth that may not occur. The objectives of our study were to document changes in behavior during the breeding season in captive maned wolves in order to determine if behaviors other than sexual (i.e., copulation) could be used to distinguish nonbreeding from breeding pairs and, further, whether successful breeding pairs (young born) could be distinguished behaviorally from breeding pairs that did not produce young (pseudopregnant). Between 1988 and 1994, behavioral data were collected during the annual reproductive season from 52 maned wolf pairings (27 males, 26 females) housed at 17 North American institutions. Breeding animals showed significant increases in rates of affiliative behaviors (approach, friendly) and the amount of time spent in close association (social) during the estrous period, compared to pre- and post-estrous periods. In contrast, the behavior of nonbreeding pairs varied little throughout the breeding season. Discriminant function analysis (DFA) showed that several behavioral measurements during certain reproductive periods were useful in discriminating between nonbreeding and breeding animals (rates of friendly and social behavior for males, marking and social behavior for females). Unsuccessful (pseudopregnant) and successful breeding pairs could be further distinguished on the basis of agonistic and approach behavior frequencies (successful females showed higher rates of agonistic and lower rates of approach behavior during certain periods; successful males had higher rates of both behaviors). Discriminant equations for key behavioral measurements and examples of their practical application are presented. DFA provides animal managers with an effective, noninvasive technique for assessing the reproductive status of maned wolf pairs. © 1996 Wiley-Liss, Inc.     

Bapx1 regulates patterning in the middle ear: altered regulatory role in the transition from the proximal jaw during vertebrate evolution

The middle ear apparatus is composed of three endochondrial ossicles (the stapes, incus and malleus) and two membranous bones, the tympanic ring and the gonium, which act as structural components to anchor the ossicles to the skull. Except for the stapes, these skeletal elements are unique to mammals and are derived from the first and second branchial arches. We show that, in combination with goosecoid (Gsc), the Bapx1 gene defines the structural components of the murine middle ear. During embryogenesis, Bapx1 is expressed in a discrete domain within the mandibular component of the first branchial arch and later in the primordia of middle ear-associated bones, the gonium and tympanic ring. Consistent with the expression pattern of Bapx1, mouse embryos deficient for Bapx1 lack a gonium and display hypoplasia of the anterior end of the tympanic ring. At E10.5, expression of Bapx1 partially overlaps that of Gsc and although Gsc is required for development of the entire tympanic ring, the role of Bapx1 is restricted to the specification of the gonium and the anterior tympanic ring. Thus, simple overlapping expression of these two genes appears to account for the patterning of the elements that compose the structural components of the middle ear and suggests that they act in concert. In addition, Bapx1 is expressed both within and surrounding the incus and the malleus. Examination of the malleus shows that the width, but not the length, of this ossicle is decreased in the mutant mice. In non-mammalian jawed vertebrates, the bones homologous to the mammalian middle ear ossicles compose the proximal jaw bones that form the jaw articulation (primary jaw joint). In fish, Bapx1 is responsible for the formation of the joint between the quadrate and articular (homologues of the malleus and incus, respectively) enabling an evolutionary comparison of the role of a regulatory gene in the transition of the proximal jawbones to middle ear ossicles. Contrary to expectations, murine Bapx1 does not affect the articulation of the malleus and incus. We show that this change in role of Bapx1 following the transition to the mammalian ossicle configuration is not due to a change in expression pattern but results from an inability to regulate Gdf5 and Gdf6, two genes predicted to be essential in joint formation.     

Eye position affects activity in primary auditory cortex of primates

BACKGROUND: Neurons in primary auditory cortex are known to be sensitive to the locations of sounds in space, but the reference frame for this spatial sensitivity has not been investigated. Conventional wisdom holds that the auditory and visual pathways employ different reference frames, with the auditory pathway using a head-centered reference frame and the visual pathway using an eye-centered reference frame. Reconciling these discrepant reference frames is therefore a critical component of multisensory integration. RESULTS: We tested the reference frame of neurons in the auditory cortex of primates trained to fixate visual stimuli at different orbital positions. We found that eye position altered the activity of about one third of the neurons in this region (35 of 113, or 31%). Eye position affected not only the responses to sounds (26 of 113, or 23%), but also the spontaneous activity (14 of 113, or 12%). Such effects were also evident when monkeys moved their eyes freely in the dark. Eye position and sound location interacted to produce a representation for auditory space that was neither head- nor eye-centered in reference frame. CONCLUSIONS: Taken together with emerging results in both visual and other auditory areas, these findings suggest that neurons whose responses reflect complex interactions between stimulus position and eye position set the stage for the eventual convergence of auditory and visual information.     

The muscle ankyrin repeat proteins: CARP, ankrd2/Arpp and DARP as a family of titin filament-based stress response molecules

CARP, ankrd-2/Arpp, and DARP, are three members of a conserved gene family, referred to here as MARPs (muscle ankyrin repeat proteins). The expression of MARPs is induced upon injury and hypertrophy (CARP), stretch or denervation (ankrd2/Arpp), and during recovery following starvation (DARP), suggesting that they are involved in muscle stress response pathways. Here, we show that MARP family members contain within their ankyrin repeat region a binding site for the myofibrillar elastic protein titin. Within the myofibril, MARPs, myopalladin, and the calpain protease p94 appear to be components of a titin N2A-based signaling complex. Ultrastructural studies demonstrated that all three endogenous MARP proteins co-localize with I-band titin N2A epitopes in adult heart muscle tissues. In cultured fetal rat cardiac myocytes, passive stretch induced differential distribution patterns of CARP and DARP: staining for both proteins was increased in the nucleus and at the I-band region of myofibrils, while DARP staining also increased at intercalated discs. We speculate that the myofibrillar MARPs are regulated by stretch, and that this links titin-N2A-based myofibrillar stress/strain signals to a MARP-based regulation of muscle gene expression.     

2-(Anilinomethyl)imidazolines as alpha(1)-adrenoceptor agonists: the identification of alpha(1A) subtype selective 2'-carboxylic acid esters and amides

2-(Anilinomethyl)imidazolines with 2'-esters or 2'-amides are potent agonists of the cloned human alpha(1)-adrenoceptors in vitro. The size and shape of the ortho substituent can have significant effects on the potency, efficacy, and subtype selectivity of these 2-(anilinomethyl)imidazolines. alpha(1A)-subtype selective agonists have been identified.     

Genome-wide profiling of promoter recognition by the two-component response regulator CpxR-P in Escherichia coli

In Escherichia coli, the two-component Cpx system comprising the CpxA sensor kinase and the CpxR response regulator modulates gene expression in response to a variety of stresses including membrane-protein damage, starvation, and high osmolarity. To date, the few known CpxR-P target operons were mostly identified by genetic screens. To facilitate the discovery of all target operons, we derived a 15-bp weighted matrix for CpxR-P recognition that takes into account the relative base frequency at each nucleotide position. This matrix essentially consists of two tandem 5'-GTAAA-3' motifs separated by a 5-bp linker. All of the 15-bp stretches on both strands of the E. coli MG1655 genome were then scored for their degree of matching with the matrix and classified in statistical deviation groups. The effectiveness of this screening is indicated by the identification of eight new target operons (ung, ompC, psd, mviA, aroK, rpoErseABC, secA, and aer) among eleven candidates tested. Moreover, the matrix score correlates with the likelihood that a site is a true target and with the relative site affinity for CpxR-P in vitro. Our data indicate that some 100 operons are under direct CpxR-P control and that the signal transduction pathway interacts with several other control circuits in manners hitherto unanticipated.     

Distinct dimer interaction and regulation in nitric-oxide synthase types I,II, and III

Homodimer formation activates all nitric-oxide synthases (NOSs). It involves the interaction between two oxygenase domains (NOSoxy) that each bind heme and (6R)-tetrahydrobiopterin (H4B) and catalyze NO synthesis from L-Arg. Here we compared three NOSoxy isozymes regarding dimer strength, interface composition, and the ability of L-Arg and H4B to stabilize the dimer, promote its formation, and protect it from proteolysis. Urea dissociation studies indicated that the relative dimer strengths were NOSIIIoxy > NOSIoxy > NOSIIoxy (endothelial NOSoxy (eNOSoxy) > neuronal NOSOXY (nNOSoxy) > inducible NOSoxy (iNOSoxy)). Dimer strengths of the full-length NOSs had the same rank order as judged by their urea-induced loss of NO synthesis activity. NOSoxy dimers containing L-Arg plus H4B exhibited the greatest resistance to urea-induced dissociation followed by those containing either molecule and then by those containing neither. Analysis of crystallographic structures of eNOSoxy and iNOSoxy dimers showed more intersubunit contacts and buried surface area in the dimer interface of eNOSoxy than iNOSoxy, thus revealing a potential basis for their different stabilities. L-Arg plus H4B promoted dimerization of urea-generated iNOSoxy and nNOSoxy monomers, which otherwise was minimal in their absence, and also protected both dimers against trypsin proteolysis. In these respects, L-Arg alone was more effective than H4B alone for nNOSoxy, whereas for iNOSoxy the converse was true. The eNOSoxy dimer was insensitive to proteolysis under all conditions. Our results indicate that the three NOS isozymes, despite their general structural similarity, differ markedly in their strengths, interfaces, and in how L-Arg and H4B influence their formation and stability. These distinguishing features may provide a basis for selective control and likely help to regulate each NOS in its particular biologic milieu.     

alpha(1)-Adrenoceptor agonists: the identification of novel alpha(1A )subtype selective 2'-heteroaryl-2-(phenoxymethyl)imidazolines

Novel 2'-heteroaryl-2-(phenoxymethyl)imidazolines have been identified as potent agonists of the cloned human alpha(1)-adrenoceptors in vitro. The nature of the 2'-heteroaryl group can have significant effects on the potency, efficacy, and subtype selectivity in this series. alpha(1A) Subtype selective agonists have been identified.