Transport and fate of dissolved organic carbon in the Lake Pontchartrain esutary,Louisiana, U.S.A.

Cycling dynamics of dissolved organic carbon (DOC) were examinedin Lake Pontchartrain estuary, Louisiana, in relation to changesin freshwater inputs. DOC concentrations ranged from 5.3 to 8.5mg C L-1 reaching their highest during high river inflow.The percentage of DOC represented by HMW DOC (or colloidal material)was greatest (ca. 11%) at stations where freshwaterdischarge from rivers and surrounding wetlands was most significant.Moreover, the lignin-phenol content of this material (ranged from 0.09 to 0.33 and from 0.11 to 0.39)confirmed that a significant fraction of colloidal organic carbon wasderived from terrestrial sources. Riverine and benthic fluxes representedthe dominant sources of DOC to the estuary. On an annual basis, riverineand benthic DOC concentrations were estimated to be 2.8 ×10 10 g C yr-1 and 8.8 × 10 10 g C yr-1, respectively, while the totalDOC pool in the estuary was 3.8 × 10 10 gC. Annual average concentrations of dissolved inorganic carbon (DIC)(1298 M) and pCO2 (5774 atm)were comparable to those found in other freshwater systems that reachedCO2 saturation levels. Net losses of DOC in the LakePontchartrain estuary appeared to be primarily controlled by heterotrophicconsumption (conversion of CO2) – whichmay have been amplified by the long residence time (approximately 120days) of DOC in this system.     

Soil Water Stress and Photosynthesis in Cotton

An experiment was conducted in SPAR systems at Florence, S.C., to obtain a data set for use in the simulation of the effect of drying soil on photosynthetic rates in cotton. The plant water status was monitored using leaf water potential and stem diameter meaurements. Reductions were noted in apparent photosynthesis rates after only 5 days of soil drying, and as anticipated, there was uniform displacement of the diurnal cycle of leaf water potential, and corresponding decreases in transpiration and CO₂ uptake. The photosynthesis-light response curves indicated that an average two-fold reduction in photosynthesis rates occurred for solar radiation greater than 250 W/m². Stem diameter change (from a nonstress pre-sunrise value) and integrated stem stress were found to be good indicators of maximum daily plant water stress. The integrated stem stress gave a measure of the duration of the stress along with its magnitude. A simulation method for predicting leaf water potential from stem diameter measurements was used to show that the magnitude and duration of plant water stress increased uniformly during the experiment. This increase was representative of the decreased rates of photosynthesis measured. These data will be used in the simulation of cotton growth and yield.     

Some factors influencing the Moroccan distribution of the western Mediterranean spur-thighed tortoise, Testudo graeca graeca L., and those precluding its survival in NW Europe

The Moroccan distribution of Testudo graeca graeca L. is defined by locality records (109) and related to data from nearby or bioclimatically equivalent meteorological stations (86) to produce a rain-temperature climagram. Tortoises attain 1900 m in the High Atlas range. Tortoises occur where mean annual rainfall (P) is up to 1062 mm, and even 1112 mm where mean minimum monthly temperature for the coolest month (m) is below 0^oC and they are usually absent unless associated (90.0%) with Quercus ilex L. and Quercus suber L. woodland. Tortoises are absent from the Arctic-Alpine and Arid or Saharan bioclimates and where, without riverine habitat, Emberger's Quotient (Q) is below 19.5 (P = 139 mm) in the Steppe bioclimate. Below Q_= 39.1, they occur (88.9%) where there is Argania spinosa (L.) Maire woodland in the south-west and other broad-leaved and mixed wood- and scrubland species elsewhere. The Moroccan climagram includes and is extended by further stations (36) in the North African and southern European ranges generally ( T. g. graeca is reported in NW Egypt). The Moroccan range potentially occupies 167 000 m². Of a total of 45 stations below 550 m in NW Europe, the Western Mediterranean climagram only overlaps 12 in more oceanic Britain and Ireland; 11 are coastal or insular and 11 where Quercus woodland extends the natural range with m below 0^oC in montane areas. Tortoises do not occur where mean annual sunshine much exceeds 3250 h in northern Africa or below c. 2400 h in NW Europe. Tortoises introduced from the Mediterranean region by the pet trade are unable to reproduce if they survive in NW Europe for insolation is insufficient for egg incubation and hatchling survival.     

High concentration of long‐snouted beaked whales (genus Messapicetus) from the Miocene of Peru

Abstract: Eight skulls of beaked whales (Cetacea, Odontoceti, Ziphiidae), in six cases associated with elements of the mandible, were collected from a limited area (about 1.5 km²) and roughly from the same stratigraphic horizon at Cerro Colorado, 35 km south‐south‐west of the city of Ica (Peru), where the late Middle Miocene basal strata of the Pisco Formation crop out. They represent the highest concentration reported of fossil Ziphiidae. These finely preserved Cerro Colorado fossils are described and assigned to a new species Messapicetus gregarius, together with another specimen collected from sediments of the same age at Cerro la Bruja (33 km south‐east to Cerro Colorado). Messapicetus gregarius shares with M. longirostris Bianucci, Landini and Varola, 1992 (Tortonian of Italy), an extremely elongated rostrum, but is clearly different from the Italian species in the more distinct maxillary tubercle and prominential notch, the more robust premaxillary crest, and the abrupt ventrolateral descent of the medial margin of the maxilla from the vertex. A parsimony analysis reveals that Messapicetus belongs to a basal clade, which includes other ziphiids with a dorsally closed mesorostral groove and prenarial basin. The high concentration of specimens belonging to the same species (some of them tentatively identified as adult males and females), combined with the presence of a calf, supports the hypothesis of site fidelity; these cetaceans might have lived in a limited region for a long period for both breeding and feeding. Besides the eight specimens of M. gregarius, strata at Cerro Colorado include many other cetacean remains (with several specimens of the pontoporiid Brachydelphis including a foetus), pinnipeds, turtles, fishes, and birds.     

Genomic and cDNA microsatellites from apricot (Prunus armeniaca L.)

We developed primers for the amplification of 24 polymorphic nuclear microsatellites in apricot (Prunus armeniaca L.). Thirteen loci originated from three genomic libraries enriched for TC, TG and AAG motifs. Eight loci were developed from three fruit EST (Expressed‐Sequence‐Tag) libraries and three from a leaf cDNA microsatellite‐enriched library. There were up to nine alleles per polymorphic locus in 12 different cultivars. No difference in allele numbers were shown between cDNA and genomic‐source loci. Mean expected heterozygosity was 0.65 (range: 0.15–0.87). Mendelian segregation was confirmed for all loci. These markers should be helpful for diversity studies, genome mapping and cultivar identification in apricot and related species.     

Characterization of the transcripts and protein isoforms for cytoplasmic polyadenylation element binding protein-3 (CPEB3) in the mouse retina

Background  

Cytoplasmic polyadenylation element binding proteins (CPEBs) regulate translation by binding to regulatory motifs of defined mRNA targets. This translational mechanism has been shown to play a critical role in oocyte maturation, early development, and memory formation in the hippocampus. Little is known about the presence or functions of CPEBs in the retina. The purpose of the current study is to investigate the alternative splicing isoforms of a particular CPEB, CPEB3, based on current databases, and to characterize the expression of CPEB3 in the retina.