Drought tolerance of two black poplar (Populus nigra L.) clones: contribution of carbohydrates and oxidative stress defence

Drought is expected to become an increasingly important factor limiting tree growth caused by climate change. Two divergent clones of Populus nigra (58-861 and Poli) originating from contrasting environments were subjected to water limitation (WL) to elucidate whether they differ in tolerance to drought, which mechanisms to avoid stress they exhibit and whether drought has an impact on the interactions between roots and shoots. Limiting water availability caused photosynthetic rate and total non-structural carbohydrate (TNC) levels to decrease in 58-861. However, starch-degrading enzyme activity and gene expression were induced in roots, and soluble sugar levels were higher than in well-watered (WW) plants. These data suggest that assimilation and partitioning of carbon to the roots are decreased, resulting in mobilization of stored starch. In contrast, the photosynthetic rate of Poli was reduced only late in the treatment, and carbohydrate levels in WL plants were higher than in WW plants. Superoxide dismutase (SOD) activity and gene expression were higher in Poli than in 58-861, even in WW plants, leading to a higher capacity to defend against oxidative stress.     

INHIBITION OF MALIGNANT CELL PROLIFERATION BY CULTURE MEDIA CONDITIONED BY CARDIAC OR SKELETAL MUSCLE

The present work is an attempt to explain the high resistance of muscles to cancer development. We used primary cultures of rat skeletal and cardiac muscle, and examined the effect of the supernatant of these cultures (conditioned medium; CM) on proliferation of cancer cells. The results demonstrated that CM inhibited the proliferation of several types of malignant cells by more than 50%, without a significant inhibition on normal cells. Cell cycle analysis revealed that CM increased the number of cells in S and G2 phases, suggesting a cytostatic effect of CM. For defining the biological properties of the factor(s) which are present in the CM, skeletal muscle cultures were grown in chemically defined medium (serum free medium). The concentrated sample was applied to a Sephadex G-50 column and three fractions were obtained. Only one fraction showed inhibitory activity. Four protein bands were observed in this fraction, as revealed by SDS-PAGE. We suggest that some, or all of these proteins are responsible for inhibition of tumor cell replication.     

The Evolution of the Crocodilia: A Conflict Between Morphological and Biochemical Data

Recent investigations into the evolution of the living Crocodilia,belonging to the suborder Eusuchia, have revealed that the genusGavialis may be its most primitive living member. New morphologicalstudies have shown that the braincase structure, neural pocket,air sinus systems, jaw adductor mechanisms, pelvic and hindlimbmorphology and epaxial musculature of the caudal region of Gavialisgangeticus do not correspond to the rest of the living Eusuchia.Contrary to the morphological findings, recent biochemical studiessuggest a sister group relationship between Gavialis gangeticusand Tomistoma schlegelii, another longirostrine eusuchian. Judgedby its morphology, Tomistoma is merely another member of thegenus Crocodylus within the Eusuchia. This conflict in dataeither means that not enough of the genome of both Gavialisand Tomistoma is known, the shared genome represents the primitivestates for these genes or that similar genotypes can give riseto rather different morphologies. As Gavialis resembles in someways a Mesozoic level of organization it is considered to bea surviving eusuchian relict.     

Sphaeroidal enrolment in middle Cambrian solenopleuropsine trilobites

Esteve, J., Zamora, S., Gozalo, R. & Liñán, E. 2010: Sphaeroidal enrolment in middle Cambrian solenopleuropsine trilobites. Lethaia, 10.1111/j.1502‐3931.2009.00205.x Fifty specimens belonging to species of Solenopleuropsis and Pardailhania from Spain and France demonstrate sphaeroidal enrolment in Cambrian trilobites for the first time. These solenopleuropsines show novel coaptative structures in different regions of the exoskeleton: in the cephalon there are vincular furrows and notches; in the thorax an articulating facet is developed at the pleural margins, with a ball and socket connection on the adaxial most portion, and an articulating half‐ring axially; the pygidium possesses an articulating facet. The interaction of these coaptative structures resulted in a sphaeroidal enrolment that was a progressive act from the first articulation between the occipital ring and the first segment to the pygidial articulating facet. A similar type of sphaeroidal enrolment is observed in the Devonian trilobite Phacops. Both Cambrian and Devonian trilobites developed a vincular furrow in the ventral surface of the cephalon to close their bodies tightly. In both cases, this is probably a convergent adaptation to protect against predators and obrution. Indeed, the enrolled trilobites are very common in obrution deposits restricted to shallow and soft muddy substrates. □Coaptative structures, convergence, Murero Formation, Pardailhania, Solenopleuropsinae, Solenopleuropsis.     

ASAPHOID TRILOBITES FROM THE ARENIG–LLANVIRN OF THE SOUTH CHINA PLATE

Abstract:  Twenty-nine Arenig and Llanvirn trilobite species, representing 20 genera in the Asaphidae, Cyclopygidae, Dikelokephalinidae, Nileidae, Raphiophoridae, Remopleurididae, Taihungshaniidae and Trinucleidae, are treated in a taxonomic review of the South Chinese Asaphida. This review is based on large collections of trilobite material made from five formations at nine localities in western Hubei, northern Hunan and southern Shaanxi, representing a wide range of benthic marine environments across the Yangtze Platform and Jiangnan Transitional Belt regions of the South China Plate. Most South Chinese representatives of the Asaphidae are reassigned to the Nobiliasaphinae on the basis of cranidial and hypostomal characters, and taxonomic revisions are given for Liomegalaspides and Opsimasaphus pseudodawanicus . Taihungshania shui and T . tachengssuensis are revised and redescribed, and the establishment of lectotypes for these species and T . brevica clarifies the status of the type material of Taihungshania . Nileus walcotti is revised and restricted biogeographically to the South China Plate; material from Xinjiang previously assigned to this species is reassigned to N .  sericeus sp. nov. The new raphiophorid species Raphioampyx sinankylosus is described. Aocaspis , Incaia and Raphioampyx are recorded for the first time from South China, and the latter two genera are also recorded for the first time from the Arenig.     

Plasticity of the phonotactic selectiveness of four species of chirping crickets (Gryllidae): Implications for call recognition

Earlier studies of phonotaxis by female crickets describe this selective behavioural response as being important in the females' choices of conspecific males, leading to reproduction. In the present study, moderate (30+) to very large data sets of phonotactic behaviour by female Acheta domesticus L., Gryllus bimaculatus DeGeer, Gryllus pennsylvanicus Burmeister and Gryllus veletis Alexander demonstrate substantially greater plasticity in the behavioural choices, as made by females of each species, for the syllable periods (SP) of model calling songs (CS) than has been previously described. Phonotactic choices by each species range from the very selective (i.e. responding to only one or two SPs) to very unselective (i.e. responding to all SPs presented). Some females that do not respond to all SPs prefer a range that includes either the longest or shortest SP tested, which fall outside the range of SPs produced by conspecific males. Old female A. domesticus and G. pennsylvanicus are more likely to be unselective for SPs than are young females. Each species includes females that do not respond to a particular SP when responding to CSs with longer and shorter SPs. The results suggest that the plasticity of phonotactic behaviour collectively exhibited by the females of each species does not ensure that choices of a male's CS effectively focus the female's phonotactic responses on CSs that represent the conspecific male. The phonotactic behaviour collectively exhibited by females of each species does not readily fit any of the models for selective processing by central auditory neurones that have been proposed to underlie phonotactic choice.     

Comprehensive assessment of carbon productivity, allocation and storage in three Amazonian forests

The allocation and cycling of carbon (C) within forests is an important component of the biospheric C cycle, but is particularly understudied within tropical forests. We synthesise reported and unpublished results from three lowland rainforest sites in Amazonia (in the regions of Manaus, Tapajós and Caxiuanã), all major sites of the Large‐Scale Biosphere–Atmosphere Programme (LBA). We attempt a comprehensive synthesis of the C stocks, nutrient status and, particularly, the allocation and internal C dynamics of all three sites. The calculated net primary productivities (NPP) are 10.1±1.4 Mg C ha⁻¹ yr⁻¹ (Manaus), 14.4±1.3 Mg C ha⁻¹ yr⁻¹ (Tapajós) and 10.0±1.2 Mg C ha⁻¹ yr⁻¹ (Caxiuanã). All errors bars report standard errors. Soil and leaf nutrient analyses indicate that Tapajós has significantly more plant‐available phosphorus and calcium. Autotrophic respiration at all three sites (14.9–21.4 Mg C ha yr⁻¹) is more challenging to measure, with the largest component and greatest source of uncertainty being leaf dark respiration. Comparison of measured soil respiration with that predicted from C cycling measurements provides an independent constraint. It shows general good agreement at all three sites, with perhaps some evidence for measured soil respiration being less than expected. Twenty to thirty percent of fixed C is allocated belowground. Comparison of gross primary productivity (GPP), derived from ecosystem flux measurements with that derived from component studies (NPP plus autotrophic respiration) provides an additional crosscheck. The two approaches are in good agreement, giving increased confidence in both approaches to estimating GPP. The ecosystem carbon‐use efficiency (CUEs), the ratio of NPP to GPP, is similar at Manaus (0.34±0.10) and Caxiuanã (0.32±0.07), but may be higher at Tapajós (0.49±0.16), although the difference is not significant. Old growth or infertile tropical forests may have low CUE compared with recently disturbed and/or fertile forests.     

Variation in Breeding Season Survival of Female Harlequin Ducks

ABSTRACT Quantifying sources of variation in demographic rates can provide insight into processes underlying population dynamics and subsequently direct wildlife conservation. In the context of avian life history, understanding patterns of variation in survival rates of breeding females is particularly relevant because this cohort often has a disproportionately large effect on population dynamics. We estimated survival probability for 144 adult female harlequin ducks (Histrionicus histrionicus) that we marked with radiotransmitters and tracked at 4 breeding areas in western North America. Model selection results indicated both regional and temporal variation in survival rates, with most mortality attributed to predation. Cumulative survival probability (±SE) during the 100-day study period was lower at 2 sites in the Rocky Mountains of Alberta, Canada (AB1 and AB2: 0.75 ± 0.11) than in the Coast Mountains of British Columbia, Canada (BC: 0.88 ± 0.08) or the Cascade Mountains of Oregon, USA (OR: 0.89 ± 0.08). Survival also was lower during incubation than nest-initiation or brood-rearing stages at all 4 study areas. In comparison to other annual cycle stages and locations, harlequin duck mortality rates were highest on the breeding grounds, suggesting that management actions designed to reduce mortality during breeding would achieve meaningful population-level benefits.