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Despite being the largest estuary on the west coast of North America, no in-depth survey of microbial communities in San Francisco Bay (SFB) waters currently exists. In this study, we analyze bacterioplankton and archaeoplankton communities at several taxonomic levels and spatial extents (i.e., North versus South Bay) to reveal patterns in alpha and beta diversity. We assess communities using high-throughput sequencing of the 16S rRNA gene in 177 water column samples collected along a 150-km transect over a 2-year monthly time-series. In North Bay, the microbial community is strongly structured by spatial salinity changes while in South Bay seasonal variations dominate community dynamics. Along the steep salinity gradient in North Bay, we find that operational taxonomic units (OTUs; 97% identity) have higher site specificity than at coarser taxonomic levels and turnover ("species" replacement) is high, revealing a distinct brackish community (in oligo-, meso-, and polyhaline samples) from fresh and marine end-members. At coarser taxonomic levels (e.g., phylum, class), taxa are broadly distributed across salinity zones (i.e., present/abundant in a large number of samples) and brackish communities appear to be a mix of fresh and marine communities. We also observe variations in brackish communities between samples with similar salinities, likely related to differences in water residence times between North and South Bay. Throughout SFB, suspended particulate matter is positively correlated with richness and influences changes in beta diversity. Within several abundant groups, including the SAR11 clade (comprising up to 30% of reads in a sample), OTUs appear to be specialized to a specific salinity range. Some other organisms also showed pronounced seasonal abundance, including Synechococcus, Ca. Actinomarina, and Nitrosopumilus-like OTUs. Overall, this study represents the first in-depth spatiotemporal survey of SFB microbial communities and provides insight into how planktonic microorganisms have specialized to different niches along the salinity gradient.

Abstract: A recent publication in Botany introduced two new taxa: a fossil orchid seed (Mycophoris) and a fossilized basidiomycete fungus (Synaptomitus) in an alleged relationship with this orchid, encased in [...]

The abundance and reproductive activity of orchids have been linked to variations in weather conditions, but few investigators have examined the relationships between orchid flowering dynamics and the distribution and abundance of mycorrhizal fungi. We quantified the abundance of flowering individuals of Corallorhiza odontorhiza, a mycoheterotrophic orchid, over a 14-year-period and mapped the distribution of individuals in six of the 14 years. For two seasons, we conducted intensive and extensive studies of the mycorrhizal fungi that were associated with C. odontorhiza. The annual abundance of flowering plants was statistically related to growing-season precipitation and winter temperature, and the distribution of individuals within the study plot was related to the abundance and distribution of appropriate host fungi. We used DNA sequencing to identify ectomycorrhizal root tips that hosted Tomentella fungi that could potentially support C. odontorhiza. We found that Tomentella spp. were distributed throughout the study plot and on all ectomycorrhizal tree species, including in areas that have historically supported few or no Orchids. However, there were fewer ectomycorrhizal trees, total ectomycorrhizal root tips, and root tips hosting Tomentella spp. in areas with few or no orchids compared to areas with abundant orchids. Furthermore, one Tomentella taxon dominated in C. odontorhiza rhizomes but was never found except immediately adjacent to C. odontorhiza plants. This suggests that abundance of flowering C. odontorhiza reflects both the presence of 'preferred' taxa and abundance of appropriate host fungi associated with ectomycorrhizal roots. Results of this research provide the first indication that the relationship between plants and mycorrhizal fungi may be influenced by both the relative abundance of fungi that are sufficient to support orchid growth and by the presence of particular fungal types that are especially good at supporting orchid growth. Key words: Corallorhiza odontorhiza; ECM; ectomycorrhiza; mycoheterotrophic; orchid; Orchidaceae; Smithsonian Environmental Research Center; Tomentella.

Meristematic activity in the bud meristem of Abies nordmanniana was visualized by ubiquitin immunohistochemical localization from before bud break and throughout shoot expansion. Ubiquitin was detected in meristematic cells either in the cytosol or nucleus, or both, depending on tissue type and developmental stage. During winter dormancy, ubiquitin was only observed in the protodermal/hypodermal layers, but at bud break in mid May, the signal expanded to the entire shoot tip. At the end of May, a clear zonation in ubiquitin localization appeared that lasted about one month. Throughout this period, ubiquitin was barely detectable in a central group of cells that might indicate an organizing center with stem cells. At the end of June, coinciding with the transition from scale leaf to needle primordia production, ubiquitin again was more prevalent in the peripheral cell layers. During shoot expansion, a strong ubiquitin signal developed in the axil of all needles. Most of these signals later disappeared, except for those few axils where buds actually developed. A strong ubiquitin signal was also observed in cells lining the young resin ducts. Our data showed that ubiquitin may be used as a marker for metabolic activity associated with seasonal development in the apical meristem. Key words: apical shoot meristem; bud development; gymnosperm; immunohistochemistry; resin ducts.

The anther is the source of several of the principal characters traditionally used for classification in Orchidaceae, especially in Epidendroideae. In particular, anther and pollinium orientation are important, but little-studied characters; it is not known whether various instances of these states are achieved in the same way. We examined variation in anther and pollinium orientation in Epidendroideae and Vanilloideae using anatomical sections of columns at successive ontogenetic stages and related the observed changes to the final anther morphology to reexamine our homology hypotheses for these characters. Anther bending in vanilloids is achieved primarily by massive expansion of the connective. In nonvandoid epidendroids it is the result of column elongation and tipping of the mature anther, while in vandoids it is due to a redirection of growth in very early ontogenetic stages. Superposed pollinia result from a reorientation of developing thecae; those is Sobralia result from incurving of the thecae, while vandoids have thecae that are directed outward (latrorse). Contrasting ontogenetic and phylogcnetic patterns suggest heterochronic changes in these characters, especially in vandoids. These observations allow us to further refine character states that are crucial to our understanding of orchid relationships. Key words: anther column; development; Epidendroideae; Orchidaceae; pollinium.

Concerns about declining populations of terrestrial orchids make it important to identify the environmental factors crucial to seedling recruitment. This study shows that seedlings of Tipularia discolor (cranefly orchid) primarily occur on decomposing wood. Extensive searches of decomposing logs and stumps in mature and successional forests revealed seedlings at 24 sites, of which 15 could be identified as originating from seven different deciduous trees and one conifer. Seeds were planted in natural habitats to test the hypothesis that germination requires decomposing wood. In one experiment, seeds were placed into soil at sites where adult plants were abundant; no germination resulted. In a second experiment, germination of seeds sown in ambient soil was compared with sowings in plots amended with decomposing wood collected from a stump where spontaneous seedlings grew. Germination was much more frequent in plots amended with decomposing wood. We conclude that germination of T. discolor is stimulated in substrates that contain decomposing wood; judging from the occurrence of spontaneous seedlings, wood from at variety of tree species offer a suitable substrate. Key words: decomposing wood; forest ecosystem; germination; mycoheterotrophy; orchid mycorrhiza; seed biology; Tipularia; Orchidaceae.

Development of anthers in three subfamilies of Orchidaceae was studied anatomically to examine homology hypotheses for pollinium number characters and to produce a model of pollinium development for the family. Serial sections of plastic-embedded embryonic inflorescences revealed that anther primordia were either flattened or ovoid; subsequent expansion of thecae and their inward (adaxial) reorientation ('rotation'), achieved by differential cell division and elongation in the connective, result in a mature anther with strongly introrse morphology and pollinia oriented side by side (juxtaposed). Strongly introrse anthers occur in at least some members of all subfamilies and are probably the basal state for the family. All anthers examined (from Orchidoideae, Spiranthoideae, and Epidendroideae) showed a single meristematic region, which would later give rise to pollen, per theca at earliest stages; septation of each of these regions resulted in four or eight pollinia per anther, while lack of septation in some members of the Epidendroideae gave two pollinia. In contrast, the two bipartite pollinia found in many Spiranthoideae and Orchidoideae were produced by adherence of the contents of two locules at a late ontogenetic stage, and should be recognized as a distinct character state. Eight pollinia result from partitioning by two longitudinal septa or a longitudinal and a transverse septum; these two morphologies may also represent separate character states. Key words: anther development; Epidendroideae; Orchidaceae; Orchidoideae; pollinium development; Spiranthoideae.

The rat intestinal imino acid carrier is chloride independent, and in rat small intestine, transport of beta-alanine, gamma-aminobutyric acid and taurine may be possible by the amino acid carrier. There is no significant interaction between the imino acid carrier and the alpha-amino-monocarboxylic acids with side chains in excess of one methyl group. The principle carrier of taurine and the only carrier of beta-alanine is the rat amino acid carrier.

A method is described by which seeds of terrestrial orchids are sown and retrieved in the field under almost natural conditions. For the first time it is possible to conduct a quantitative study of orchid germination in situ and observe seasonal growth and mortality of seedlings. The technique has also enabled us to investigate the relation between the site where the seeds are sown, the availability of an appropriate fungus to infect the seeds, and seedling establishment in the soil. Five local species were studied. Corallorhiza odontorhiza, Goodyera pubescens, and Galearis spectabilis all began to germinate in May-June, after 23-30 weeks in the soil. These species differed in their dependency on infection at germination time, but none of the seedlings developed beyond the point of rupturing the testa except when infected. Seeds of Liparis lilifolia and Tipularia discolor did not germinate within the first 12 months of the experiment. The implications and potential uses of this field sowing technique for further studies and for other kinds of minute seeds are discussed.

A study of the mechanisms controlling the secretion of pancreatic spasmolytic polypeptide (PSP) from pig pancreas is presented. PSP is a 106-amino acid peptide isolated form pig pancreatic extracts which is a potential growth factor. The study protocol involved observing PSP secretion in perfused isolated pig pancreas and in pancreatic secretion in response to a meal in young conscious pigs. The results show PSP to be an exocrine product whose secretion is regulated by parasympathetic mechanisms, including cholinergic and peptidergic pathways, and by endocrine mechanisms involving cholecystokinin octapeptide and secretin.

Naturally occurring seedlings of Neuwiedia veratrifolia were found in three localities in Sabah, Borneo, Malaysia. Seedlings consisted of an irregular oblong protocorm and a terminal leafy rooted shoot. Protocorms contained mycotrophic tissue of the kind typical of orchid mycorrhiza (tolypophagy). This finding demonstrates an important synapomorphy between Neuwiedia and other orchids and strongly supports the monophyly of Orchidaceae in the broad sense, including apostasiod orchids. Key words: germination; mycorrhiza; Neuwiedia; orchid; Orchidaceae; protocorm; seedling.

Aerobic metabolism of human quadriceps muscle: in vivo data parallel measurements on isolated mitochondria. Am J Physiol Endocrinol Metab 280: E301-E307, 2001.--The aim of the present study was to examine whether parameters of isolated mitochondria could account for the in vivo maximum oxygen uptake ([VO.sub.2 max]) of human skeletal muscle. [VO.sub.2 max] and work performance of the quadriceps muscle of six volunteers were measured in the knee extensor model (range 10-18 mmol [O.sub.2] [multiplied by] [min.sup.-1] [multiplied by] [kg.sup.-1] at work rates of 22-32 W/kg). Mitochondria were isolated from the same muscle at rest. Strong correlations were obtained between [VO.sub.2 max] and a number of mitochondrial parameters (mitochondrial protein, cytochrome [aa.sub.3], citrate synthase, and respiratory activities). The activities of citrate synthase, succinate dehydrogenase, and pyruvate dehydrogenase, measured in isolated mitochondria, corresponded to, respectively, 15, 3, and 1.1 times the rates calculated from [VO.sub.2 max]. The respiratory chain activity also appeared sufficient. Fully coupled in vitro respiration, which is limited by the rate of ATP synthesis, could account for, at most, 60% of the [VO.sub.2 max]. This might be due to systematic errors or to loose coupling of the mitochondrial respiration under intense exercise. skeletal muscles; maximal oxygen uptake; work rate; respiration; adenosine triphosphate synthesis

A cladistic analysis of Orchidaceae was undertaken for 98 genera using 71 morphological apomorphies based on a reconsideration of previous character analyses and newly discovered variation. The equally weighted analysis found 60,000 most parsimonious trees with low consistency (CI = 0.29) but high retention (RI = 0.83). The strict consensus reveals a significant amount of structure, and most traditionally recognized subfamilies are supported as monophyletic, including the Apostasioideae, Cypripedioideae, Spiranthoideae, and Epidendroideae. Orchidoideae in the broad sense are paraphyletic, giving rise to spiranthoids. Vanilloids are sister to epidendroids, although exhibiting several states otherwise found only in clearly basal groups, such as Apostasioideae. The nonvandoid epidendroids are poorly resolved, due to a high degree of homoplasy. The vandoids appear to be monophyletic, contrary to recent molecular evidence, possibly due to repeated parallel development of the vandoid character suite. The importance of vegetative characters as evidence putatively independent from floral features is demonstrated in the placement of Tropidia. Implied weighting analysis of these data resulted in similar patterns at high levels, although the Orchidoideae and Spiranthoideae may each be monophyletic and the nonvandoid epidendroids are more resolved. The high degree of structure implied in previous orchid classifications must be reconsidered, given the poor resolution at lower levels in the present trees. Key words: cladistics; classification; morphology; Orchidaceae; systematics.