Sexual and individual morphometric variation in Libycosaurus (Mammalia, Anthracotheriidae) from the Maghreb and Libya

Anthracotheres of late Middle Miocene and Late Miocene age have been described from several localities in northern Africa, all of them currently assigned to the genus Libycosaurus Bonarelli, although in several previous works they were assigned to Merycopotamus Falconer and Cautley, a considerably younger and specialised form from the Indian subcontinent which has quite different dental and cranial morphology. Three species of Libycosaurus have been named, but there has been some doubt about the morphometric variation within the various species, with some authors such as Gaziry (1987) placing the fossils from Sahabi (Latest Miocene, Libya) and Beglia (end Middle Miocene to basal Late Miocene, Tunisia) into the same species despite marked size differences, and others (Ducrocq et al., 2001) creating a species for a restricted sample of small specimens from Nementcha (Late Middle Miocene, Algeria), but which overlaps with the range of size variation of Beglia fossils. The aim of this paper is to examine the available samples in greater depth in order to understand the morphometric variation in these anthracotheres. It is confirmed that the Beglia sample is quite variable (Black, 1972), both morphologically and metrically, but it is concluded that it nevertheless belongs to a single species, because specimens from some of the localities within the Beglia Formation (e.g. Loc. 17 in the lower levels at Beglia) span the entire range of variation (Pickford, 1994). The sample from Nementcha cannot be distinguished from the Beglia sample on any consistent metric or morphological basis, but in general the specimens fall at the low end of the range of variation of the Beglia sample. It is thus likely that L. algeriensis is a synonym of L. anisae. The Sahabi and Chad samples (L. petrocchii), in contrast, fall above the known range of variation of the Beglia material in almost all metric features, but are close to it morphologically, and they are considered to represent a species distinct from the Beglia sample.     

Foraminiferal assemblages and the confinement index as tools for assessment of saline intrusion and human impact in the Mekong Delta and neighbouring areas (Vietnam)

Foraminiferal assemblages have been studied in 33 samples from the Can Gio region to the north of the Mekong Delta and from two regions of the Delta: the Tra Vinh province, in the middle part of the Delta; and the Ca Mau peninsula, to the south. Two plates, including 117 pictures, illustrate the species. These assemblages, either through the nature of the test or through the calculation of the confinement index Ic, clearly indicate differences in the balance between continental and marine influences, the Tra Vinh province being subject to the strongest freshwater influence. The decrease of calcareous specimens and the increase of Ic indicate the impact of deforestation in the Ca Mau peninsula, the influence of organic matter in shrimp ponds, and the impact of pollution in a tidal channel. The distribution of foraminiferal assemblages described in this study should be used as part of a reference point for further observations with a view to assessing environmental impacts of increasing human activities and/or global change.     

Climatic limits of pink bollworm in Arizona and California: effects of climate warming

The distribution and abundance of pink bollworm (Pectinophora gossypiella Saunders (PBW)) in cotton in Arizona and California was examined using a validated weather-driven, physiologically based demographic model of cotton and PBW integrated into a geographic information system (GIS). Survival of diapause larvae during winter as affected by low temperatures is a key factor determining the range of PBW. Winter survival was estimated using data from Gutierrez et al. (Can. Entomol. 109 (1977) 1457) and Venette et al. (Environ. Entomol. 29 (5) (2000) 1018). The model was run continuously over the period 1 January 1995 to 31 December 2003 using observed weather data from 121 locations. Three output variables were mapped as measures of PBW persistence: over-winter survival of diapause PBW larvae, cumulative daily PBW larval densities over the season, and the number of diapause larvae produced during the season. The distribution of pink bollworm is predicted to be restricted to the relatively frost-free cotton growing areas of Arizona and Southern California where it currently reaches pest status. The model predicts that extension of PBW's range into the Central Valley of California is unlikely. The analysis questions the efficacy of an ongoing area-wide effort to prevent the establishment of PBW in the Central Valley of California. Four global warming scenarios were examined to estimate the effects on the potential geographic range of PBW. Average observed daily temperatures were increased 1.0, 1.5, 2.0 or 2.5 °C, respectively, in the four scenarios. Scenarios with average increases of 1.5–2.5 °C predicted that the range of PBW would expand into the Central Valley of California and the severity of the pest would greatly increase in areas of current infestation.     

Seed size: a key trait determining species distribution and diversity of dry tropical forest in northern India

The study examined the relationships among seed size, plant distribution and abundance in a dry tropical forest of northern India. Results indicated that small-seeded species, which were generally wind-dispersed, were more widely distributed, at this local scale, compared to large-seeded species. However, the proportional abundance and basal cover of seed size categories indicated that the structure of the dry forest was largely determined by the medium- to large-seeded species. There was a considerable amount of redundancy within each seed size group, which added to the species diversity. Variability in seed size and the variable degree of shade-tolerance permit the species to occupy the full range of the gradient of light environments of the forest floor. This study revealed that in little to moderately disturbed locations seedlings of large-seeded species increased in abundance, whereas in extremely perturbed locations seedlings of species with medium-sized to small seeds were more abundant.     

Interactions between root and shoot competition among four plant species in an alpine meadow on the Tibetan Plateau

At low altitudes, the interactions between root and shoot competition on plant growth have been extensively studied, and such interaction effects were found to be positive, negative, or neutral. However, little is known about such effects at high altitudes where the environmental conditions are harsher than those at low altitudes. We carried out a field experiment in an alpine meadow in the northeast Tibetan Plateau to test the hypothesis that a negative interaction between root and shoot competition exists for alpine plant species. Root and shoot competition were experimentally manipulated in the four grass species (Kobresia humilis, Saussurea superba, Stipa aliena and Elymus nutans). We found that K. humilis and S. aliena grew better without competition, whereas S. superba grew better with shoot competition and E. nutans grew better with root competition. The interactions between root and shoot competition were negative in K. humilis, positive in S. superba, but neutral in S. aliena and E. nutans, suggesting that the interaction effects are species-specific. This study also suggested that alpine plants may trade off both plant–plant interactions and competition shift between root and shoot to adapt to stressful environments.     

Maastrichtian calcareous nannofossil biostratigraphy and paleoecology in the Equatorial Atlantic (Demerara Rise, ODP Leg 207 Hole 1258A)

Species richness, absolute and relative abundances of Maastrichtian calcareous nannofossils were analyzed in Hole 1258A. Absolute abundances of taxa were used for the biozonation of this hole and the record of successive bio-events. Distribution patterns of cool water taxa such as Ahmuellerella octoradiata, Gartnerago segmentatum and Kamptnerius magnificus underscore two major cooling events. These events occurred during Chron C31r and during undifferentiated Chrons C31n to C30n. The latter event appears to be accompanied by lowered productivity, as expressed by the lower abundances of fertility index taxa Biscutum constans and Zeugrhabdotus spp. An end-Maastrichtian warming event is recorded in Chron C29r by the sudden drop in abundance of cool water taxa and acme of tropical taxon Micula murus. The disappearance of B. constans just before this event and the significant increase of Micula decussata, respectively, suggest lowered productivity and high-stress environmental conditions prior to the K/P boundary (Cretaceous-Paleogene). These results correlate very well with the climatic scenario proposed by Li and Keller (1998a) in South Atlantic Hole 525A as suggested by stable isotopes and distribution patterns of planktic foraminifera.     

Xenobiotic metabolism of plant secondary compounds in juniper (Juniperus monosperma) by specialist and generalist woodrat herbivores, genus Neotoma

Mammalian herbivores routinely consume diets laden with often-toxic xenobiotics, yet the manner in which mammalian herbivores detoxify these plant secondary compounds (PSC) is largely unknown. Theory predicts that specialists rely more heavily on functionalization pathways whereas generalists rely on conjugation pathways to metabolize PSC in their diet. We took a pharmacological approach to determine how a specialist (Neotoma stephensi) of juniper foliage (Juniperus monosperma) and a generalist (N. albigula) may process the same dietary PSC. We investigated the xenobiotic metabolizing enzymes of the specialist and generalist on a control diet and a low (25%) juniper diet. We also examined enzyme activities in the specialist on a high (70%) juniper diet. We assayed for cytochrome P450 concentration and biotransformation activities of three specific cytochrome P450 isozymes (CYP1A, CYP2B, CYP3A), NAD(P)H:quinone oxidoreductase, glutathione conjugation, sulfation and glucuronidation. Results provide partial evidence for the hypothesis in that the specialist and generalist consuming juniper at a level similar to their natural diet, differ in the level of conjugation enzyme activity with generalists having higher activity overall than specialists.     

Benthic foraminiferal assemblages of the Cretaceous platform carbonate succession in the Yavca area (Bolkar Mountains, S Turkey): biostratigraphy and paleoenvironments

The microbiostratigraphic analysis of the three outcrop sections from the Cretaceous inner platform carbonate succession in the Yavca area (Bolkar Mountains) allows to recognize the four local benthic foraminiferal zones. These are: (1) Voloshinoides murgensis and Praechrysalidina infracretacea Cenozone in the Lower Aptian; (2) Pseudorhapydionina dubia and Biconcava bentori Cenozone in the Middle-Upper Cenomanian; (3) Ostracoda and Miliolidae Interval Zone in the probable Turonian, represented by dolomitized limestones without any significant markers; (4) Moncharmontia compressa and Dicyclina schlumbergeri Cenozone in the Coniacian-Santonian. The benthic foraminiferal assemblages correspond to those in other areas of the Mediterranean realm, with the exception of a lack of alveolinids and orbitolinids due to unfavorable environmental conditions (inner platform, restricted shelf). After the regionally well-known emergence during the late Aptian, Albian and early Cenomanian, very shallow subtidal to intertidal conditions were re-established during the middle-late Cenomanian time. The Coniacian-Santonian benthic foraminiferal assemblage shows an increase in diversity and abundance as a result of open marine influence, confirmed by the presence of larger foraminifera (Dicyclina), Rotaliidae and radiolitid fragments. Thaumatoporella and Aeolisaccus-bearing wackestone intercalations still indicate the existence of sporadic restricted environment conditions. The Cretaceous shallow-water platform carbonate succession of the Yavca area is conformably overlain by gray pelagic limestones with calcispheres and planktonic foraminifera. The Campanian flooding of the Bolkar Da? carbonate platform resulted in drowning of the pre-existing biota and facies.     

Comprehensive in vivo secondary structure of the SARS-CoV-2 genome reveals novel regulatory motifs and mechanisms

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Ceratosphinctes (Ammonitina, Kimmeridgian) in Mexico: from rare but typical inhabitant of west-Tethyan epioceanic and epicontinental waters to a geographically widespread ammonite genus

Two specimens of Ceratosphinctes represent the first record of this taxon in Mexico (Mexican Huasteca), and are interpreted as Ceratosphinctes rachistrophus amatitlaensis nov. subsp. The subspecies level is used with biogeographic significance, most probably indicating incoming propagules and adaptation to local environmental requirements. Biostratigraphy, based on agreement of the composition of the ammonite assemblage that included C. rachistrophus amatitlaensis nov. subsp. and the previous interpretation of ammonite assemblages with Idoceras in Mexico by Villaseñor et al., indicates precise correlation with Tethyan records (uppermost-Lower to lowermost-Upper Kimmeridgian). The dispersion pattern available for Ceratosphinctes is interpreted as related to ecospace enlargement during the relative sea-level highstand of the late-Early Kimmeridgian.     

Surface-water chemistry and fertility variations in the tropical Atlantic across the Paleocene/Eocene Thermal Maximum as evidenced by calcareous nannoplankton from ODP Leg 207, Hole 1259B

Calcareous nannoplankton assemblages at Ocean Drilling Program (ODP) Site 1259 on Demerara Rise (western equatorial Atlantic) underwent an abrupt and fundamental turnover across the Paleocene/Eocene Thermal Maximum (PETM) ~55.5 m.y. ago. The PETM is marked by a dissolution interval barren or nearly-barren of nannofossils due to the rapid acidification of the world oceans. Toweius, Fasciculithus, and Chiasmolithus sharply decrease at the onset, whereas Chiasmolithus, Markalius cf. M. apertus, and Neochiasmolithus thrive immediately after the event, which also signals the successive first appearances of Discoaster araneus, Rhomboaster, and Tribrachiatus. The environmental indications of these changes were further investigated by correspondence analysis on quantitative nannofossil counts. The PETM event has been attributed to CO₂-forced greenhouse effects. At Site 1259, the elevated pCO₂ and subsequent lowered surface-water pH values at the onset of the PETM caused intensive carbonate dissolution, producing the nannofossil-barren interval. The chemically stressed habitats may well have also induced the evolution of ephemeral nannofossil “excursion taxa”, such as Rhomboaster and malformed discoasters (D. araneus and Discoaster anartios). Based on its sudden increase, Markalius cf. M. apertus is considered to have been a local opportunistic species that took advantage of the surface-water changes. At the same time, a presumably higher runoff from continental areas fertilized the western equatorial Atlantic as indicated by an increase in the abundance of r-mode specialists preferring high-nutrient conditions, such as Chiasmolithus, Coccolithus pelagicus, and Hornibrookina arca. Contrasts between the results of this study and previous work at ODP Site 690 in the Southern Ocean, the New Jersey continental margin, and the central paleoequatorial Pacific further demonstrate that the response to the PETM can be influenced by local differences in geologic setting and oceanographic conditions.     

Systematic alteration of in vitro metabolic environments reveals empirical growth relationships in cancer cell phenotypes

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Ovarian follicular growth suppression by long-term treatment with a GnRH agonist and impact on small follicle number,oocyte yield,and in vitro embryo production in Zebu beef cows

The aim of the present study was to evaluate small follicle number, oocyte yield, and in vitro embryo production (IVEP) in Zebu beef cows treated long term with a GnRH agonist to suppress ovarian follicular growth. Nelore (Bos indicus) cows (n = 20) showing regular estrous cycles were randomly assigned to one of two groups: control (n = 10, placebo ear implant without a GnRH agonist); GnRH agonist (n = 10, GnRH agonist ear implant containing 9.4-mg deslorelin). All cows underwent an ovum pick-up (OPU) session 14 days (Day 14) before the start of treatments (Day 0) followed by seven OPU–IVEP procedures at 30-day intervals (Days 0, 30, 60, 90, 120, 150, and 180). Semen from a single batch of a previously tested bull was used for all the IVEP. Cows treated with agonist reported a decrease over time in the proportion of animals with a (CL; P ≤ 0.05) and large follicles (>10 mm, P ≤ 0.05). These cows had a lesser number of medium + large follicles (>5 mm; 1.74 ± 0.5 vs. 4.13 ± 0.5; P ≤ 0.05), greater number of small follicles (2–5 mm; 44.3 ± 2.8 vs. 30.8 ± 1.8; P ≤ 0.05), greater yield of cumulus-oocyte complexes (COCs; 21.0 ± 2.3 vs. 15.6 ± 1.9; P ≤ 0.05), greater proportion of COCs cultured (79.2 vs. 73.9%; P ≤ 0.05), COCs cleaved (10.6 ± 1.5 vs. 6.8 ± 1.1, P ≤ 0.05), and cleaved rate (52.8 vs. 44.3%; P ≤ 0.05) compared with control cows. The number (3.4 ± 0.7 vs. 3.0 ± 0.6; P > 0.05) and proportion (16.5 vs. 19.1%; P > 0.05) of blastocysts produced were similar between agonist and control cows, respectively. The study has shown that Zebu beef cows treated long term with a GnRH agonist had follicular growth restricted to small follicles. This did not compromise the ability of oocytes to undergo IVF and embryonic development.     

Genetic and environmental effects of growth and production of secondary compounds in Cladonia cristatella

This is the first study under controlled conditions to evaluate genetic and environmental variables acting on the whole lichen. Four cloned lines of Cladonia cristatella, derived from single spores and re-associated with teh normal algal partner (Trebouxia erici), were grown in a phytotron and chemically analysed. Growth, as measured by cover, was significantly affected by clone and consistently decreased at lower temperatures and at higher light intensities. The two biogenetically distinct pathways leading to the characteristic secondary products were affected differently by factors related to the genetic component (clone), the developmental stage (age) and the environment (temperature and light). Products fo the barbatic acid pathway, leading to depsides, were detected in the youngest lichenized hyphae, and the concentrations did not change significantly with age. products of the didymic acid pathway, leading to dibenzofurans, were incrasingly abundant in progressively older squamules. The four clones showed significantly different capacities for the production of compounds by the two pathways and significantly different responses to the environmental factors studied. The concentrations of compounds from the barbatic acid pathway increased at lower temperatures; those of compounds from the didymic acid pathway either changed little or decreased appreciably according to clone. Of the factors studied, light had the least effect on chemistry. Between-pathway variation in production of secondary products was greater than within-pathway variation.     

Larval growth inhibition of the spiny bollworm,Earias insulana, by some steroidal secondary plant compounds

The effect of 23 secondary plant compounds including a series of steroidal aglycones and glycosides, on larval growth and pupation ofEarias insulana (Boisd.) was investigated. Larvae did not develop when fed on artificial diets containing 0.2% solamargine, solasonine, tomatine, digitonin, saponin, nomilin, lawsone or coumarin. Some growth-retarding activity was found with diets containing 0.2% ajmalicine, capsaicin, quercetin, glycyrrhizin and glycerrhetic acid. The eight compounds highly active at 0.2% were also bioassayed at 0.1, 0.05 and 0.01%: larvae did not pupate when fed on diets containing 0.1% solasonine, tomatine or nomilin, whereas solamargine and coumarin were active even at 0.05%. Preliminary structure-activity relationships were evaluated for the active steroidal glycosides.

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Larvale Wachstumshemmung des ägyptischen Baumwollkapselwurms, Earias insulana,durch einige steroide sekundäre Planzeninhaltstoffe

Zusammenfassung Es wurde die Wirkung von 23, einem künstlichen Nährmedium einverleibten, sekundären Pflanzeninhaltstoffen, unter ihnen eine Reihe steroider Aglucone und Glycoside, auf das Larvenwachstum und die Verpuppung vonEarias insulana untersucht. Larven entwickelten sich nicht in mit 0.2% Solamargin, Solasonin, Tomatin, Digitonin, Saponin, Nomilin, Lawsone und Coumarin versetzten Nährmedien. Auf Medien, die 0.2% Ajmalicin, Capsaicin, Quercetin, Glycyrrhizin and Glycyrrhetinsäure enhielten, war das Larvenwachstum verzögert. Die 8 bei 0.2% hoch wirksamen·Substanzen wurden auch bei 0.1, 0.05 und 0.01% getestet. Die Larven verpupten sich nicht auf 0.1% Solasonin, Tomatin und Nomilin und auf 0.05% Solamargin und Coumarin. Vorläufige Struktur-Wirksamkeit-Beziehungen wurden für die aktiven steroiden Glycoside vorgeschlagen.