A glossary of plant hair terminology

This is a compilation of English terms having to do with hairs and hairy surfaces of plants. The glossary is divided into two sections. Part I includes terms for types and attributes of individual hair kinds and hair clusters. Part II deals with kinds and characteristics of induments.     

Chemosystematics and taxonomy of Ambrosia chamissonis

Specimens of the variable strand ragweeds of the Pacific Coasts of North and South America have commonly been divided among two or more specific or subspecific taxa. The results of this study indicate that they comprise a single heteromorphic and chemically variable species, Ambrosia chamissonis (Less.) Greene. Morphological and chemical variants within the complex show no overall correlation, and variation within and between populations is such as to suggest specific continuity. Less variable populations south of California's Monterey Peninsula appear to be derived from limited introductions from the north, and to owe their relative uniformity to genetic drift and development from limited progenitor stock. Genetic drift linked to self-pollination is evident within populations and within progeny groups developed from naturally produced seed, and is here termed ‘ethological drift’. Two varieties are recognized within the species: var. cuneifolia is found near and north of the mouth of the Columbia River. and is characterized by relatively large fruiting involucres with flattened spines and a tendency for unlobed leaves and pilose pubescence; var. chamissonis, with smaller involucres and basally inflated or terete spines, is found throughout the remainder of the range, and includes two intergrading forms—forma chamissonis with unlobed leaves and forma bipinnatisecta with pinnately decompound leaves.     

Signaling pathways mediating chemotaxis in the social amoeba, Dictyostelium discoideum

Chemotaxis, or cell migration guided by chemical cues, is critical for a multitude of biological processes in a diverse array of organisms. Dictyostelium discoideum amoebae rely on chemotaxis to find food and to survive starvation conditions, and we have taken advantage of this system to study the molecular regulation of this vital cell behavior. Previous work has identified phosphoinositide signaling as one mechanism which may contribute to directional sensing and actin polymerization during chemotaxis; a mechanism which is conserved in mammalian neutrophils. In this review, we will discuss recent data on genes and pathways governing directional sensing and actin polymerization, with a particular emphasis on contributions from our laboratory.     

The impact of surfactant protein-A on ozone-induced changes in the mouse bronchoalveolar lavage proteome

Background  

Ozone is a major component of air pollution. Exposure to this powerful oxidizing agent can cause or exacerbate many lung conditions, especially those involving innate immunity. Surfactant protein-A (SP-A) plays many roles in innate immunity by participating directly in host defense as it exerts opsonin function, or indirectly via its ability to regulate alveolar macrophages and other innate immune cells. The mechanism(s) responsible for ozone-induced pathophysiology, while likely related to oxidative stress, are not well understood.     

Orangutan α-satellite monomers are closely related to the human consensus sequence

Alpha-satellite is a family of tandemly repeated DNA found at the centromeric regions of all human and primate chromosomes. Human α-satellite subsets are largely chromosome-specific and have been further grouped into four suprachromosomal families (SFs), each characterized by a unique set of monomeric types. Although chimpanzee and gorilla α-satellites share sufficient sequence similarity to fit the established SFs, the assumption that the derived human α-satellite consensus and monomeric types represent the sequence of ancestral repeats remains unestablished. By using oligonucleotide primers specific for a conserved region of human α-satellite DNA, we have PCR amplified, cloned, and characterized α-satellite sequences from the orangutan genome. Nucleotide sequence analysis demonstrated that orangutan α-satellite is formed by a single monomeric type that is significantly closer in percentage of sequence identity (mean = 92%, range = 89–96%) to the overall consensus of human α-satellite than to the monomeric types corresponding to the four SFs. Use of cloned sequences as hybridization probes to orangutan genomic DNA digested with a panel of restriction enzymes showed that most orangutan α-satellite subsets are characterized by a monomeric construction. The subset homologous to clone PPY2-5 is organized in distinct higher-order repeat structures consisting of 18 adjacent monomers. By FISH two clones, PPY3-4 and PPY3-5, proved to be specific for the α-satellite on the orangutan homologs of human Chromosomes (Chrs) 10 and 8, respectively. Our data indicate that there was an ancestral monomeric type displaying high sequence similarity to the overall human consensus from which the different great ape and human subsets and SFs may have originated. Received: 24 November 1997 / Accepted: 29 January 1998