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Based on extensive new material, 2088 valves resulting from search sampling of ~500 kg of sediment, the Pliocene chiton biodiversity of the Mondego Basin (Portugal) is reassessed. Twelve species were identified, assigned to seven genera. Eight species are new for the Pliocene of Portugal, as well as two of the genera: Hanleya, Acanthochitona. Two taxa are described as new: Ischnochiton loureiroi n. sp. and Lepidochitona rochae n. sp. Until now, the polyplacophoran European Neogene record was too poorly known to be of help in generating a clear picture of the Miocene to present-day biogeography of the group. This new wealth of data from western Iberia, in conjunction with recent data from the Loire Basin Upper Miocene assemblages (France), allows clarification the Late Miocene to Recent eastern Atlantic and Mediterranean biogeography of the Polyplacophora. The northern range of warm-water northeast Atlantic and Mediterranean Polyplacophora experienced a sharp contraction since, at least, Late Miocene to Early Pliocene times. Warm-water chiton species represented in the Upper Miocene of the Loire Basin of NE France (European-West African Province) and the Pliocene of the Mondego Basin of central-west Portugal (Pliocene French-Iberian Province) are today confined to the southern Mediterranean-Moroccan Molluscan Province.
Sweet corn (Zea mays L.) tolerance to dicamba and several other herbicides is due to cytochrome P450 (CYP)-mediated metabolism and is conferred by a single gene (Nsf1). Tolerance varies by CYP genotypic class, with hybrids homozygous for functional CYP (Nsf1Nsf1) being the most tolerant and hybrids homozygous for mutant CYP alleles (nsf1nsf1) being the least tolerant. The herbicide safener cyprosulfamide (CSA) increases tolerance to dicamba by stimulating the expression of several CYPs. However, the extent to which CSA improves the tolerance of different sweet corn CYP genotypic classes to dicamba is poorly understood. Additionally, the effect of growth stage on sweet corn sensitivity to dicamba is inadequately described. The objective of this work was to quantify the significance of application timing, formulation, and CYP genotypic class on sweet corn response to dicamba. Hybrids representing each of the three CYP genotypes (Nsf1Nsf1, Nsf1nsf1, nsf1nsf1), were treated with dicamba or dicamba + CSA at one of three growth stages: V3, V6, or V9. Across all timings, the nsf1nsf1 hybrid was the least tolerant to dicamba, displaying 16% higher crop injury levels 2 wk after treatment and 2,130 kg ha−1 lower ear mass yields compared with the Nsf1Nsf1 hybrid. The V9 growth stage was the most susceptible time for dicamba injury regardless of genotypic class, with 1.89 and 1,750 kg ha−1 lower ear mass yields compared with the V3 and V6 application timings, respectively. The addition of CSA to dicamba V9 applications reduced the injury from dicamba for all three genotypic classes; however, it did not eliminate the injury. The use of Nsf1Nsf1 or Nsf1nsf1 sweet corn hybrids along with herbicide safeners will reduce the frequency and severity of injury from dicamba and other CYP-metabolized herbicides.
The cancellarid genus Sveltia Jousseaume, 1887, is widespread in western European and North African Neogene marine fossil assemblages. In Pliocene deposits it is commonly represented by Sveltia varicosa (Brocchi, 1814), which until recently was considered a widely distributed taxon in the Mediterranean Sea and adjacent Atlantic faunas. A recent review of the species from the Pliocene of Italy and Spain (Guadalquivir Basin), leading to the erection of S. confusa, prompted the reassessment of the Sveltia material from the Atlantic Pliocene of the Portuguese Mondego Basin and the subsequent description of Sveltia sofiae n. sp. Consequently, a mosaic of species has emerged from what was previously viewed as the broad Atlanto-Mediterranean range of the widespread and quite variable S. varicosa. From a biogeographic standpoint, it is now clear that S. varicosa was a Mediterranean species, occurring east of the Alboran Sea. Sveltia confusa had a mainly Atlantic distribution, from the French Pliocene Ligerian Gulf to the Gulf of Cadiz, at least, and straddling the Strait of Gibraltar into the Alboran Sea. Sveltia sofiae n. sp. was endemic to western Iberia, represented today only in the western Portuguese Mondego Basin. Sveltia is a thermophilic genus. Since early Pliocene times, because of northeastern Atlantic sea surface temperature decline, it underwent a southward range contraction, occurring today—in the eastern Atlantic—from Cape Blanc, Mauritania, south. This range reduction was coupled with the post mid-Piacenzian southward contraction of the Pliocene Mediterranean-West African tropical molluscan province and the consequent rise of the present-day Mediterranean-Moroccan subtropical province.
Twenty four species of Cancellariidae belonging to eleven genera occurring in the Neogene Bocas del Toro assemblages, Caribbean Panama, are discussed and figured. The following seven species are described as new: Cancellaria pilula n. sp., Cancellaria isabelae n. sp., Cancellaria stri n. sp., Cancellaria axelolssoni n. sp., Massyla corpulenta n. sp., Aphera trophis n. sp., Admetula valientensis n. sp. The cancellarid genus Charcolleria Olsson, 1942 is considered a synonym of Massyla H. Adams and A. Adams, 1854. Of the 24 species present in the Bocas del Toro, 12 are known also to occur elsewhere in the tropical American Neogene. This level of endemism is high, but not as high as that reported from other Tropical American Neogene assemblages, probably due to the very central geographic location within the Gatunian Province of the Bocas assemblages.
Thirty species of Cancellariidae in 11 genera from the Miocene Gatun Formation in the Panama Canal area, Caribbean Panama, are discussed including two species not represented by specimens suitable for formal description. The following 11 species are described as new: Cancellaria harzhauseri n. sp., Cancellaria mixta n. sp., Bivetiella dilatata n. sp., Euclia alacertata n. sp., Pyruclia tweedledum n. sp., Pyruclia tweedledee n. sp., Massyla toulai n. sp., Aphera aphrodite n. sp., Axelella cativa n. sp., Agatrix agathe n. sp., Ventrilia coatesi n. sp. This assemblage of cancellariids is very diverse and highly endemic, with 18 (60 percent) species found only in the Miocene Gatun Formation. These assemblages all lie within the Gatunian Neogene Paciphile Molluscan Unit 1 (GNPMU1).
Today, the marine gastropod genus Cittarium is present only in the West Indies faunas, represented by a single species C. pica, also known from the Pleistocene of Bermuda. Herein Cittarium praepica n. sp. is described from the Upper Miocene Cercado Formation of the Dominican Republic. This is the oldest fossil record for the genus in the eastern Tropical America. The new species is compared to the Pleistocene to Recent Caribbean C. pica and to C. maestratii Lozouet, 2002 of the Upper Oligocene of France. The importance of this new record for the geological history and the biogeography of the genus are discussed.
Until now, the buccinid genus Chauvetia was considered of European or West African origin, and is still endemic to these areas today. This paper describes the oldest representative of the genus, Chauvetia inopinata nov. sp., from the upper Burdigalian-lower Langhian transition Cantaure Formation of Venezuela. This surprising record suggests a New World tropical origin to the genus and subsequent immigration to the Old World before the earliest known Old World record, which is upper Tortonian. We postulate that this pre-late Tortonian (pre-8.12–7.42 Ma) dispersal of the tropical Gatunian west-Atlantic Chauvetia into the tropical East Atlantic European-West African Province most probably happened during the 10.71–9.36 Ma interval (early–mid Tortonian) during which the Circum-Tropical Current weakened, and the northward Intra-Caribbean Current had started, enhancing the Gulf Stream and the North Atlantic Current. This new data constitutes compelling evidence of a pre-Pliocene eastward dispersal of New World shallow marine organisms across the Atlantic.
In contrast to the immense effort that has been put into the geological survey and stratigraphic study of the Neogene of Bocas del Toro region (Panama), little research has been done on the systematics of this region's rich gastropod assemblages. This is the first paper dealing primarily with the Bocas Neogene gastropod assemblages (Strombidae) since the pioneer work of Olsson (1922). Neogene strombid assemblages of the Dominican Republic have recently been reviewed and updated, and, therefore, the Strombidae are a suitable starting point for the revision of the gastropod assemblages from the Neogene of Bocas del Toro. Six species of Strombus are described, three of them new: S. acanthospira n. sp., S. pugiloides, S. gatunensis, S. elegantissimus n. sp., S. vermeiji n. sp. and S. cf. floridanus.
The Marginellidae Fleming and the Cystiscidae Stimpson, herein collectively referred to as marginelliform gastropods, are convergent families of thermophilic marine gastropods. Shallow-water marginelliform gastropods are found in the Ibero-Moroccan Gulf and Mediterranean, diversity rapidly increasing towards tropical West Africa. Surprisingly, in the tropical and subtropical European Miocene fossil record, marginelliform genera of tropical affinity such as Persicula Schumacher and Prunum Herrmannsen, occurring today in West Africa, are altogether missing. Others, such as Marginella Lamarck, are present only in the southwestern Iberian and Mediterranean Neogene record. This work describes the marginelliform gastropods from the Atlantic Iberian Neogene. Ten species are recorded, of which three are new, Persicula mikhailovae n. sp., Gibberula costae n. sp., and Gibberula brebioni n. sp. This study shows that Gibberula Swainson and Volvarina Hinds have been present in Europe since the Eocene. Marginella may have originated in southern Africa and migrated north to Europe in the Miocene, never extending further north than west central Portugal. Persicula and Prunum probably originated in the Caribbean and migrated east during the Pliocene, following closure of the Central American Seaway. The colonization of the Pliocene European Atlantic coast by gastropods of these genera was selective, only where high sea-water temperature and high productivity were combined. These findings suggest that post-Messinian recolonization of the Mediterranean during the Pliocene was a complex process, involving colonization by groups originating in various regions of the Atlantic, including Europe, Africa and the Americas.
The rate of appearance of glycerol in the systemic circulation is determined from the enrichment of arterial blood glycerol when labelled glycerol is infused intravenously. This value provides a good measure of whole-body lipolysis during fasting, except that arterial infusion and venous sampling, if feasible, would probably give a higher more-accurate value. Lipolysis occurs primarily in adipose tissue, although other tissues contribute, notably muscle. Measurement is based on the difference in the enrichment of the glycerol entering and leaving the tissue. Lipolysis is underestimated by the extent to which glycerol released by lipolysis does not enter the systemic circulation, as occurs when lipolysis takes place in the non-hepatic tissue of the splanchnic bed. Glycerol released into the systemic circulation is utilized mainly by liver, although kidney and muscle are also major users of glycerol. Measurement of glycerol utilization is based on the amount of labelled glycerol taken up by the tissues. Other tissues probably utilize glycerol to a smaller extent, but in total this represents a significant amount. Most glycerol taken up by liver is converted to glucose. Glucose is probably the major source of glycerol-3-phosphate used in the esterification of fatty acids by adipose tissue.
The contribution of gluconeogenesis to glucose production is estimated from the enrichment of the H bound to C-5 of glucose relative to either that bound to C-2 of glucose or the enrichment in body water on ingesting 2H2O in the fasted state. Contributions of all gluconeogenic substrates are included in the estimate and the limitation of an uncertain precursor enrichment removed. The half-life of 2H2O in body water precludes a repeat study for many weeks. Glycogen cycling could result in underestimation, but there is evidence that glycogen cycling does not occur in liver in the fasted state. Gluconeogenesis has been estimated by mass-isotopomer-distribution analyses, usually by administering 13C-labelled glycerol. Underestimates emphasize the major limitation of the method, i.e. the need to assume a single enrichment of the precursor pool. Estimates of gluconeogenesis from isotopomer distribution in arterial-blood glucose and lactate on infusing [U-13C6] glucose are unreliable, as a proportion of the glucose is formed from glycerol and from amino acids not converted to glucose via pyruvate. Loss of label in the Krebs cycle and relying on enrichment of arterial-blood lactate as a measure of hepatic pyruvate further add to the uncertainty. Estimates of the rate of gluconeogenesis by NMR are obtained by subtraction of the rate of glycogenolysis determined by NMR from the rate of glucose production. Estimates are then the mean rate for the period over which glycogen contents are measured. Technical considerations can limit the accuracy of analyses and result in overestimates.
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