Geographic isolation and evolution of Mediterranean endemic Cyclamen: insights from chloroplast trnL (UAA) intron sequence variation

 In this study we construct a phylogenetic hypothesis for the relatedness among disjunct subspecies of Cyclamen repandum and its two allopatric congeners, C. creticum and C. balearicum in order to examine the evolutionary divergence of currently isolated populations across the western Mediterranean. The most parsimonious phylogenetic tree obtained from sequencing the cpDNA trnL (UAA) intron suggests a major phylogeographic divide in southern Greece between two clades. The first clade comprises samples of C. repandum subsp. peloponnesiacum (from the Peloponnese) and C. creticum (from Crete). The second comprises samples of C. repandum subsp. repandum (from Croatia, Italy, southern France, Corsica, Sardinia and Sicily), C. repandum subsp. rhodense (from Rhodes and Kos) and C. balearicum (from the Balearic Islands and southern France). These data suggest that C. creticum has evolved in allopatry from C. repandum subsp. peloponnesiacum and that C. balearicum and C. repandum ssp. rhodense have diverged from C. repandum subsp. repandum at its western and eastern distribution limits. At one small site on Corsica, a population of C. repandum may have introgressed with relictual populations of C. balearicum. These divergence patterns illustrate how a phylogenetic perspective can be used to better understand the evolution of endemism in the Mediterranean flora. Received February 19, 2001 Accepted August 22, 2001     

Cyclic nucleotide alterations in mixed leukocyte reaction: a preliminary report

Endogenous cyclic adenosine and guanosine monophosphate (cAMP, cGMP) levels were studied in human peripheral blood lymphocytes during mixed leukocyte reactions (MLR). cAMP level was consistently elevated in one-way MLR, with good correlation to 3H-thymidine uptake in these reactions. In contrast, cGMP level was practically unchanged. Irradiation of reacting cell populations resulted in inhibition of cyclic nucleotide phosphodiesterase (PDE) activity. These results suggest that metabolic alterations in cAMP may be associated with immune reactions of cellular recognition.     

Diminished Reovirus Capsid Stability Alters Disease Pathogenesis and Littermate Transmission

Reovirus is a nonenveloped mammalian virus that provides a useful model system for studies of viral infections in the young. Following internalization into host cells, the outermost capsid of reovirus virions is removed by endosomal cathepsin proteases. Determinants of capsid disassembly kinetics reside in the viral σ3 protein. However, the contribution of capsid stability to reovirus-induced disease is unknown. In this study, we found that mice inoculated intramuscularly with a serotype 3 reovirus containing σ3-Y354H, a mutation that reduces viral capsid stability, succumbed at a higher rate than those infected with wild-type virus. At early times after inoculation, σ3-Y354H virus reached higher titers than wild-type virus at several sites within the host. Animals inoculated perorally with a serotype 1 reassortant reovirus containing σ3-Y354H developed exaggerated myocarditis accompanied by elaboration of pro-inflammatory cytokines. Surprisingly, unchallenged littermates of mice infected with σ3-Y354H virus displayed higher titers in the intestine, heart, and brain than littermates of mice inoculated with wild-type virus. Together, these findings suggest that diminished capsid stability enhances reovirus replication, dissemination, lethality, and host-to-host spread, establishing a new virulence determinant for nonenveloped viruses.     

Isomeric lipid signatures reveal compartmentalized fatty acid metabolism in cancer

The cellular energy and biomass demands of cancer drive a complex dynamic between uptake of extracellular FAs and their de novo synthesis. Given that oxidation of de novo synthesized FAs for energy would result in net-energy loss, there is an implication that FAs from these two sources must have distinct metabolic fates; however, hitherto, all FAs have been considered part of a common pool. To probe potential metabolic partitioning of cellular FAs, cancer cells were supplemented with stable isotope-labeled FAs. Structural analysis of the resulting glycerophospholipids revealed that labeled FAs from uptake were largely incorporated to canonical (sn-) positions on the glycerol backbone. Surprisingly, labeled FA uptake also disrupted canonical isomer patterns of the unlabeled lipidome and induced repartitioning of n-3 and n-6 PUFAs into glycerophospholipid classes. These structural changes support the existence of differences in the metabolic fates of FAs derived from uptake or de novo sources and demonstrate unique signaling and remodeling behaviors usually hidden from conventional lipidomics.     

Presence of prostaglandins E2 and A2 in canine gastric secretions

The presence of prostaglandins (PGs) was determined in gastric juice obtained from 3 conscious dogs, provided with a chronic gastric fistula. Outputs of acid (mequiv min^?1) and PGs (pg min^?1) were measured in gastric secretions stimulated by pentagastrin (100 or 200 ng kg^?1min^?1). Prostaglandin activity was estimated, after extraction and thin layer chromatography, by radioimmuno-assay of the PGB formed by treatment with alkali. Tritiated PGs were added to gastric juice for the purpose of correcting for PGs recovery. Using this method, the minimum mass of PGB which could be satisfactorily distinguished from zero was 25 pg. Prostaglandins A₂ and E₂ were present in pentagastrin-activated gastric secretions and averaged (mean ± SE, n = 8) 200.7 ± 18.1 and 260.1 ± 18.0 pg min^?1 respectively. The identity of PGA₂ and PGE₂ was confirmed by gas liquid chromatography combined with mass spectrometry. The amount of PGE₂ converted to PGA₂ during extraction, separation and conversion procedures was estimated from the amount of [³H] PGA₂ found when only [³H] PGE₂ had been added to a sample of gastric juice and averaged 14.5% ± 2.0. Our preliminary results support the possibility that PGE₂ and PGA₂ may be of physiological importance in the regulation of canine gastric secretions.     

Data-Limited Population-Status Evaluation of Two Coastal Fishes in Southern Angola Using Recreational Catch Length-Frequency Data

Excessive truncation of a population’s size structure is often identified as an important deleterious effect of exploitation, yet the effect on population persistence of size-structure truncation caused by exploitation is often not quantified due to data limitations. In this study, we estimate changes in eggs per recruit (EPR) using annual length-frequency samples over a 9 year period to assess persistence of the two most important recreational fishes in southern Angola: west coast dusky kob (Argyrosomus coronus) and leerfish (Lichia amia). Using a length- and age-structured model, we improve on an existing method to fit this type of model to length-frequency data and estimate EPR. The objectives of the methodological changes are to add flexibility and robustness to the approach for assessing population status in data-limited situations. Results indicate that dusky kob presents very low levels of EPR (5%-10% of the per recruit reproductive capacity in the absence of fishing) in 2013, whereas large inter-annual variability in leerfish estimates suggest caution must be applied when drawing conclusions about its exploitation status. Using simulated length frequency data with known parameter values, we demonstrate that recruitment decline due to overexploitation leads to overestimation of EPR values. Considering the low levels of EPR estimated for the study species, recruitment limitation is not impossible and true EPR values may be even lower than our estimates. It is, therefore, likely that management action, such as the creation of Marine Protected Areas, is needed to reconstitute the west coast dusky kob population.