Effects of root-feeding nematodes on aboveground net primary production in a North American grassland

The impact of nematode consumption on aboveground net primary production (ANPP) was addressed by treating two areas of mixed-grass prairie with the nematicide carbofuran. Monthly assessments of shoot biomass and nematode populations were made from each treated and control site for two growing seasons. Seasonal mean density of root-feeding nematodes was reduced approximately 82% by carbofuran. ANPP was significantly greater in the treated plots for both seasons in Site 1 but only for the second year in Site 2. Increases in ANPP averaged 51% in Site 1 and 26% in Site 2. It was estimated that root-feeding nematodes reduced ANPP by 16 times more than they consumed.     

Adrenal medullary chromaffin granule peptides: Two major ovine peptides and their precursor

An octapeptide and decapeptide which are not derived from proenkephalin were isolated from ovine adrenal chromaffin granules. Their sequences are AsnLeuAspProLysLeuAsp Leu and ValAlaGluLeuAspGlnLeuLeuHisTyr. These two peptides were found to be derived from a single precursor peptide which has also been isolated and sequenced. The proteolytic cleavage occurs at a Lys-Arg site typical of prohormone to hormone cleavages.     

The infant gut resistome associates with E. coli,environmental exposures,gut microbiome maturity,and asthma-associated bacterial composition

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Direct cloning of the trxB gene that encodes thioredoxin reductase.

A strain was constructed which contains mutations in the genes encoding thioredoxin (trxA) and thioredoxin reductase (trxB) such that filamentous phage f1 cannot grow. The complementation of either mutation with its wild-type allele permits phage growth. We used this strain to select f1 phage which contain a cloned trxB gene. The location of the gene on the cloned fragment was determined, and its protein product was identified. Plasmid subclones that contain this gene overproduce thioredoxin reductase.     

Anatomy of the larva of Amathia vidovici (Bryozoa: Ctenostomata) and phylogenetic significance of the vesiculariform larva

Amathia vidovici (Vesiculariidae) has a lecithotrophic coronate larva. The apical disc of A. vidovici larvae is more complex than that of other vesiculariids and includes a new cell type, which may be glial-like in function. A massive nerve nodule consists only of neural processes; as no ganglia or other evidence of interneurons were found, sensory cells apparently innervate their effectors directly. Putative synaptic junctions within the nerve nodule indicate that both receptor and effector cells send processes to this neuropile. Some 44 intercoronal cells of three types, two of which are new, are interspersed among the approximately 40 coronal cells. Juxtapapillary bodies, a unique sensory complex previously known only from Bowerbankia gracilis larvae, also occur in A. vidovici. A large refractile body, which is of uncertain function and is positioned near the center of the larva, is described for the first time. A comparison of vesiculariid larvae that have been studied at the ultrastructural level reveals that larvae of Amathia vidovici and Bowerbankia gracilis are more similar to each other than either is to B. imbricata. Differences between the two Bowerbankia species, however, may reflect relative detail of their study and differences in interpretation rather than intergenic plasticity. Nevertheless. a distinctive suite of larval characteristics are shared by other members of the family Vesiculariidae, justifying a specific name—vesiculariform—for their larvae. A number of the defining characteristics of vesiculariform larvae also appear in the carnosan superfamily Victorelloidae. This finding is consistent with arguments based on adult characteristics that the Victorelloidea are ancestral to the Vesicularioidea. If this geneology is correct, one can predict that those vesiculariform traits which originated in the victorellids are plesiomorphic not only to the Family Vesiculariidae but to all sister taxa placed in the Vesicularioidea. © 1993 Wiley-Liss, Inc.     

Sugar orthocarbonates

A simple procedure is described for preparing sugar orthocarbonates. It is based on treating the corresponding thionocarbonate in pyridine with cupric acetate and an alcohol, such as methanol, ethanol, or isopropyl alcohol. Treatment of 1,2:5,6-di-O-isopropylidene-D-mannitol 3,4-thionocarbonate with diols, such as 1,2-ethanediol, 1,2-propanediol, or 1,2:5,6-di-O-isopropylidene-D-mannitol, also gave orthocarbonates. Methyl thionocarbonate, S-methyl xanthate, and dithiobis(thioformate) derivatives of 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose all gave the trimethyl orthocarbonate upon treatment with methanol in the presence of pyridine and cupric acetate. The structure of the orthocarbonates was proved by elemental analysis, n.m.r., and mass spectra, and by treatment with mild acid to form carbonates. Treatment of 1,2:5,6-di-O-isopropylidene-3-thio-D-altritol 3,4-thionocarbonate with methanol or ethanol gave the corresponding orthothiocarbonate, but on treatment with 1,2-ethanediol or with sodium ethoxide the 3,4-episulfide resulted.     

Breeding biology,diet and vocalization of the Helmet Vanga,Euryceros prevostii,on the Masoala Peninsula,Madagascar

La Morco, G. & Thorstrom, R. 2000. Breeding biology, diet and vocalization of the Helmet Vanga Euryceros prevostii on the Masoala Peninsula, Madagascar. Ostrich 71 (3&4): 400-403. The endemic Helmet Vanga, Euryceros prevostii, was studied from October to December 1997, with incidental observations from October to December 1993-1997, on the Masoala Peninsula, northeastern Madagascar. Three types of vocalizations of this species were associated with territorial, alarm and contact calls, respectively. Nests were open cups placed in the forks of trees or at the apex of small trees. Nests were composed of interlaced grasses in the nest bawl, woven plant fibres supporting the centre of the nest and lichen/moss on the exterior portion of the nest. Average clutch size was 2.7 (n = 6 nests). During incubation, either adult was on the nest 99% of the time. The reproductive output was 1.8 young fledged per nest (n = 4 nests) with 75% nest success (3/4). Of the 106 prey items recorded, 91% were invertebrates and 9% verte-brates. Cockroaches, butterflies, moths, crickets, katydids and beetles represented the most numerous insect prey taken, representing 73% of the identified prey. [A French translation of the abstract is provided on p. 403.]     

Long-term history of chemoautotrophic clam-dominated faunas of petroleum seeps in the Northwestern Gulf of Mexico

Summary Chemoautotrophic clam-dominated assemblages are commonly associated with petroleum seepage on the continental slope of the Gulf of Mexico. We examine the persistence and resilence of these communities by evaluating downcore trends in abundance, biomass, and trophodynamics in communities from four separate petroleum seep sites on the Louisiana continental slope. Some petroleum seep sites retained optimal habitat for some species continuously over geologically-relevant periods of time. More commonly, however, habitat optimality varied substantially over time scales of hundreds of years. Thus, one important characteristic of these sites was the degree of persistence of the chemoautotrophic biota. A fauna typically was persistent over a time span of a few hundred years, but was typically not persistent over a longer time span. The mechanisms producing local extinction remain unclear, however temporal variations in juvenile survivorship seem to be substantially larger than temporal variations in larval settlement, to the extent that the heavily taphonomically-biased record of juvenile individuals permits such a conclusion. When local extinctions occurred in the chemoautotrophic biota, the biota was replaced by a normal slope biota or a mixture of a normal slope biota and the juveniles of chemoautotrophic species that failed to survive to adulthood. Thus, the only faunal transitions were between specific chemoautotrophic faunas and the non-chemoautotrophic fauna. Not one distinctive faunal transition between two chemoautotrophic faunas was observed. Accordingly, each discrete chemoautotrophic fauna was resilient over long time scales; time scales of geological importance.