Paper partition chromatography of interspecific hybrids in the genus Drosophila

Summary Paper chromatographic analysis of interspecific hybrids within the Genus Drosophila showed that they present a biochemical pattern different from either parental species. Sometimes new spots appear in the chromatogram of the hybrid, while in all cases spots present in the pattern of the parents appear much more intense. These spots have been identified as a riboflavin mononucleotide and riboflavine.With 8 Figures in the text     

The Sirius Passet Lagerstätte of North Greenland—A geochemical window on early Cambrian low‐oxygen environments and ecosystems

The early Cambrian Sirius Passet fauna of northernmost Greenland (Cambrian Series 2, Stage 3) contains exceptionally preserved soft tissues that provide an important window to early animal evolution, while the surrounding sediment holds critical data on the palaeodepositional water‐column chemistry. The present study combines palaeontological data with a multiproxy geochemical approach based on samples collected in situ at high stratigraphic resolution from Sirius Passet. After careful consideration of chemical alterations during burial, our results demonstrate that fossil preservation and biodiversity show significant correlation with iron enrichments (Fe_HR/Fe_T), trace metal behaviour (V/Al), and changes in nitrogen cycling (δ¹⁵N). These data, together with Mo/Al and the preservation of organic carbon (TOC), are consistent with a water column that was transiently low in oxygen concentration, or even intermittently anoxic. When compared with the biogeochemical characteristics of modern oxygen minimum zones (OMZs), geochemical and palaeontological data collectively suggest that oxygen concentrations as low as 0.2–0.4 ml/L restricted bioturbation but not the development of a largely nektobenthic community of predators and scavengers. We envisage for the Sirius Passet biota a depositional setting where anoxic water column conditions developed and passed over the depositional site, possibly in association with sea‐level change, and where this early Cambrian biota was established in conditions with very low oxygen.     

Small scale preparation of skeletal muscle mitochondria, criteria of integrity, and assays with reference to tissue function

Mitochondria prepared in small scale from skeletal muscle were studied with respiration measurements and low temperature spectroscopy. The method of preparation was developed for 25–100 mg tissue with pigeon breast muscle as model organ. The yield was 40%. Data collected during the developmental work were used to evaluate criteria of mitochondrial quality. The cytochrome c conservation, i.e. cytochrome c per mitochondrial quantity in the preparation relative to that in the tissue, is a most useful test parameter. It is bounded between 0–100%. Proportionality between the state 3 rate and the cytochrome c conservation was not rejected by statistical tests. The respiratory control ratio (RCR) was also highly correlated to the cytochrome c conservation. These correlations might be extrapolated to 100% conservation to give hypothetical tissue values. The cause for the correlations is discussed. The P/O ratio showed only weak dependence on the cytochrome c conservation and the state 4 rate s howed no dependence. Other, rather insensitive test parameters are also discussed. The pigeon breast muscle mitochondria isolated by the final method showed cytochrome c conservation of 73 ± 9% (n = 16). They are compared with pig biceps femoris mitochondria prepared by the same method. The two types of mitochondria show many similarities. Some differences may be explained by a different amount of inner mitochondrial membrane relative to mitochondrial protein. The pig tissue contains ten times less mitochondrial protein than the pigeon tissue does. (Mol Cell Biochem 174: 55–60, 1997)     

Temporal occurrence of planktotrophic bivalve larvae identified morphologically and by single step nested multiplex PCR

We report the application of a recently developed molecularmethod, single step nested multiplex PCR (SSNM-PCR) assay andmicroscopy to identify and investigate temporal patterns ofbivalve larvae in a Danish estuary, Isefjord. All samples werecollected during the SUSTAINEX program from June to November2001. Using the molecular assay, larvae could be categorizedinto six groups: the blue mussel, Mytilus edulis, Ensis spp.,species of the Myoidae superfamily (Mya spp.), the common cockle(Cardiidae family), members of the Abra and Macoma genera ofthe Tellinoidae superfamily and members of the surf clam genera,Spisula spp. A seventh group was composed of unknown larvae.Greater resolution was possible by microscopy, but only forrelatively large and intact individuals (>150–200 µm).The molecular approach was capable of differentiating betweenlarvae regardless of shell size. Where it was possible to directlycompare identifications based on both methods, concordance washigh for M. edulis, Macoma balthica/Abra alba and E. americanus,whereas identification of Myoidae spp. and Cardiids was lessconsistent. Over the course of the study, two patterns of larvaloccurrence were observed. Larvae from species known to exhibita protracted annual spawning period (M. edulis, Myoidae spp.,Mysella bidentata and Cardiids) were present in the water columnthroughout the sampling period, whereas larvae of Abra alba,Barnea candida, E. americanus, Macoma balthica, Musculus marmoratusScrobicularia plana and Tapes pullastra appeared at clearlydefined periods.     

Sex, seasonal, and stress-related variations in elasmobranch corticosterone concentrations.

Serum corticosterone was previously studied in numerous elasmobranch fishes (sharks, skates and rays), but the role of this steroid, widespread throughout many taxa, has yet to be defined. The goal of this study was to test whether corticosterone varied in response to acute and chronic capture stress, and across the reproductive cycle in the bonnethead shark, Sphyrna tiburo, and Atlantic stingray, Dasyatis sabina. Serum corticosterone in S. tiburo increased following capture and again 24 h post-capture, possibly caused by interference with 1alpha-hydroxycorticosterone, the primary stress hormone in elasmobranchs. Higher serum concentrations in males compared to females were observed in both species. Variations in corticosterone also occurred during the reproductive cycle in both species. Consistent with other taxa, elevations in male bonnethead sharks and stingrays coincided with peak testicular development and mating. Elevations in female bonnethead sharks occurred from the time of mating through sperm storage into early gestation. In contrast, corticosterone levels in female stingrays were low during their protracted mating season, but elevated through late gestation and parturition. These results indicate that corticosterone has a limited role, if any, in acute and chronic stress associated with capture in S. tiburo, but likely has physiological functions associated with its glucocorticoid properties across the reproductive cycle of both species.