Seed germination traits of Ailanthus altissima,Phytolacca americana and Robinia pseudoacacia in response to different thermal and light requirements

Invasion of alien plant species (IAS) represents a serious environmental problem, particularly in Europe, where it mainly pertains to urban areas. Seed germination traits contribute to clarification of invasion dynamics. The objective of this research was to analyze how different light conditions (i.e., 12-hr light/12-hr darkness and continuous darkness) and temperature regimes (i.e., 15/6°C, 20/10°C and 30/20°C) trigger seed germination of Ailanthus altissima (AA), Phytolacca americana (PA) and Robinia pseudoacacia (RP). The relationship between seed germination and seed morphometric traits was also analyzed. Our findings highlight that temperature rather than light was the main environmental factor affecting germination. RP germinated at all tested temperatures, whereas at 15/6°C seeds of AA and PA showed physiological dormancy. RP had a higher germination capacity at a lower temperature, unlike AA and PA, which performed better at the highest temperatures. Light had a minor role in seed germination of the three species. Light promoted germination only for seeds of PA, and final germination percentage was 1.5-fold higher in light than in continuous darkness. Seed morphometric traits (thickness [T], area [A] and volume [V]) had a significant role in explaining germination trait variations. The results highlight the importance of increasing our knowledge on seed germination requirements to predict future invasiveness trends. The increase in global temperature could further advantage AA and PA in terms of germinated seeds, as well as RP by enhancing the germination velocity, therefore compensating for a lower germination percentage of this species at the highest temperatures.     

Stress integrated tests and cytological analyses reveal Brassica villosa subsp. drepanensis seed quality decrease upon long-term storage

Under stress integrated germination test (SIGT), seeds undergo osmo-saline stresses, which enable to detect differences in vigour of long-term stored seeds with high germination percentage (G%). The quality of Brassica villosa subsp. drepanensis seeds stored in a genebank (at ? 20°C for 16 years) was compared with seeds at harvest by standard germination tests (GT), SIGT and cytogenetic analysis. No differences were detected in G% and mean germination time under GT. Conversely, SIGT performed with NaCl ? 0.9 MPa osmotic potential did not influence G% at harvest but reduced that of stored seeds, SIGT at ? 1.4 MPa reduced G% of both. Cytogenetic analysis showed reduction of mitotic index, appearance of chromosomal aberrations and smaller nucleoli in stored seeds compared with harvest seeds germinated in water. SIGT at ? 0.9 MPa had no effect on mitotic index, but increased chromosome aberrations and nucleoli number. SIGT at ? 1.4 MPa inhibited G% of harvest and stored seeds, reduced mitoses in harvest and completely prevented it in stored seeds. The results indicate that GT does not faithfully reflect the quality of stored seeds, with misinterpretation of their vigour, whereas SIGT and cytogenetical parameters are sensitive, reliable and inexpensive methods for early prediction of genetic erosion in germplasm banks.     

Testing the Equality of Dependent Variances

The likelihood ratio test for testing equality of vgE;2 correlated variables is developed. In general, evaluation of the test statistic involves the iterative optimization of a likelihood function with 1 + v(v – 1)/2 parameters. The explicit form of the test statistic is derived in the bivariate case, and an iterative algorithm for determining the maximum likelihood estimates is suggested. A limited Monte Carlo study determines the behavior of the proposed procedure under the null hypothesis and variety of parameter values.     

Slow Delivery of the Selective Cholecystokinin Agonist pBC 264 into the Rat Nucleus Accumbens Using Microspheres

Abstract: Neuropeptides have been shown to play a critical role in adaptational processes, probably by long-term modulation of neuronal pathways. It could therefore be interesting to study behavioral changes induced by chronic local stimulation of neuropeptide receptors. With this aim poly(lactide-co-glycolide) microspheres loaded with a highly potent, peptidase-resistant, cholecystokinin (CCK)-B-selective CCK peptidomimetic agonist (pBC 264) were prepared by a water in oil in water emulsion solvent evaporation method and stereotaxically implanted into the anterior part of the rat nucleus accumbens. Two different kinds of loaded polymeric microspheres differing only by the stabilizing agent [ovalbumin (OVA) or Pluronic F 68] added to the inner emulsion were used. The histological and behavioral studies done 24 h and 8 days after implantation of nonloaded microspheres in the nucleus accumbens indicated that the microspheres were well tolerated. The in vivo release of the selective CCK-B agonist pBC 264 (associated with a tracer dose of [³H]pBC 264) from microspheres prepared with OVA was very fast (92% after 6 h), whereas only 26% (88 pmol) of pBC 264 was released from the formulation with Pluronic F 68 after 24 h. Eight days after implantation 36% of pBC 264 had diffused from the microspheres, and 8% (∼30 pmol) was still present in the brain concentrated around the site of administration. In all cases the released material was found to correspond to intact pBC 264, thus demonstrating the possibility of obtaining a slow controlled release of peptide in vivo. This method opens up interesting perspectives to study the long-term effects of neuropeptides.     

Divergence in germination traits among arctic and alpine populations of <Emphasis Type="Italic">Koenigia islandica</Emphasis>: light requirements

Light is known to regulate conservative germination strategies and the formation of seed banks. Although these strategies are crucial to survival in tundra environments—especially for annuals—light requirements for germination in arctic–alpine species are seldom investigated. Furthermore, environmental differences between arctic and alpine regions are expected to lead to evolutionary divergence among conspecific populations in seed germination strategies. In this study, we report important differences in germination light requirements among six arctic and alpine populations of the annual Koenigia islandica. Light had little effect on germination of the seeds from Iqaluit (Nunavut, Canada), Yukon (Canada), and Jasper (Alberta, Canada), whereas the seeds from the most severe climates, Svalbard (Norway) and Colorado (USA), had strong light requirements. Stratification of the seeds had little influence on their germination light requirements, with the exception of the population from Dovre (Norway), in which it induced a strong light requirement. Possible adaptive explanations and some implications of these observed germination patterns are discussed.     

Measurement of 7-dehydrocholesterol and cholesterol in hair can be used in the diagnosis of Smith-Lemli-Opitz syndrome

7-dehydrocholesterol (7-DHC) and cholesterol (CHOL) are biomarkers of Smith-Lemli-Opitz Syndrome (SLOS), a congenital autosomal recessive disorder characterized by elevated 7-DHC level in patients. Hair samples have been shown to have great diagnostic and research value, which has long been neglected in the SLOS field. In this study, we sought to investigate the feasibility of using hair for SLOS diagnosis. In the presence of antioxidants (2,6-ditert-butyl-4-methylphenol and triphenylphosphine), hair samples were completely pulverized and extracted by micro-pulverized extraction in alkaline solution or in n-hexane. After microwave-assisted derivatization with N,O-Bis(trimethylsilyl)trifluoroacetamide, the analytes were measured by GC-MS. We found that the limits of determination for 7-DHC and CHOL were 10 ng/mg and 8 ng/mg, respectively. In addition, good linearity was obtained in the range of 50–4000 ng/mg and 30–6000 ng/mg for 7-DHC and CHOL, respectively, which fully meets the requirement for SLOS diagnosis and related research. Finally, by applying the proposed method to real hair samples collected from 14 healthy infants and two suspected SLOS patients, we confirmed the feasibility of hair analysis as a diagnostic tool for SLOS. In conclusion, we present an optimized and validated analytical method for the simultaneous determination of two SLOS biomarkers using human hair.     

Metabolome and water status phenotyping of Arabidopsis under abiotic stress cues reveals new insight into ESK1 function

Metabolomic investigation of the freezing-tolerant Arabidopsis mutant esk1 revealed large alterations in polar metabolite content in roots and shoots. Stress metabolic markers were found to be among the most significant metabolic markers associated with the mutation, but also compounds related to growth regulation or nutrition. The metabolic phenotype of esk1 was also compared to that of wild type (WT) under various environmental constraints, namely cold, salinity and dehydration. The mutant was shown to express constitutively a subset of metabolic responses which fits with the core of stress metabolic responses in the WT. But remarkably, the most specific metabolic responses to cold acclimation were not phenocopied by esk1 mutation and remained fully inducible in the mutant at low temperature. Under salt stress, esk1 accumulated lower amounts of Na⁺ in leaves than the WT, and under dehydration stress its metabolic profile and osmotic potential were only slightly impacted. These phenotypes are consistent with the hypothesis of an altered water status in esk1 , which actually exhibited basic lower water content (WC) and transpiration rate (TR) than the WT. Taken together, the results suggest that ESK1 does not function as a specific cold acclimation gene, but could rather be involved in water homeostasis.