Karyotype of North American shortnose sturgeon Acipenser brevirostrum with the highest chromosome number in the Acipenseriformes

The shortnose sturgeon Acipenser brevirostrum was revealed to have a larger number of chromosomes than previously reported for other sturgeon species. Its chromosome number ranged from 362 to 372 (of ten specimens examined), showing intraindividual variation. The karyotype of metaphase with the highest chromosome number (372) consisted of 89 pairs of macrochromosomes and 97 pairs of microchromosomes (fundamental number; NF=550). Although the microchromosomes were relatively shorter than the macrochromosomes, most of them had discernible arms and centromeres. Silver-stained nucleolar organizer regions (Ag-NORs) were localized on the telomeric regions of 5 pairs of chromosomes (Ag-NORs=10): 4 were made up of small meta/submetacentrics and 1 of acrocentrics. Polyploidy of A. brevirostrum should be hexaploid based on the karyotype, numerous chromosomes, Ag-NORs, and previously reported large genome size (ca. 13pg DNA/cell).Supplementary material to this paper is available in electronic format at http://dx.doi.org/10.1007/s10228-004-0257-z     

39K nuclear magnetic resonance and a mathematical model of K+ transport in human erythrocytes

³⁹K nuclear magnetic resonance was used to measure the efflux of K⁺ from suspensions of human erythrocytes [red blood cells (RBCs)], that occurred in response to the calcium ionophore, A23187 and calcium ions; the latter activate the Gárdos channel. Signals from the intra- and extracellular populations of ³⁹K⁺ were selected on the basis of their longitudinal relaxation times, T ₁, by using an inversion- recovery pulse sequence with the mixing time, τ₁, chosen to null one or other of the signals. Changes in RBC volume consequent upon efflux of the ions also changed the T ₁ values so a new theory was implemented to obviate a potential artefact in the data analysis. The velocity of the K⁺ efflux mediated by the Gárdos channel was 1.19±0.40 mmol (L RBC)⁻¹ min⁻¹ at 37°C.     

Somatic hybrids between unilateral cross-incompatible Petunia species

Summary Somatic hybrid plants regenerated following the fusion of leaf mesophyll protoplasts of Petunia parodii with those isolated from a cell suspension of albino P. inflata. These two species exhibit a unilateral cross-incompatability with a pre-zygotic mode of reproductive isolation preventing hybridizations with P. inflata as the maternal parent. Selection of somatic hybrids relied on the fact that unfused or homokaryon protoplasts of P. parodii did not develop beyond the cell colony stage while those of the putative somatic hybrids and albino P. inflata parent produced callus. Green somatic hybrid calluses were readily identified against the white background of P. inflata following complementation to chlorophyll synthesis proficiency and continued growth in hybrid cells. Shoots, and ultimately flowering plants, were identified as somatic hybrids based on their floral morphology and colour, chromosome number and the fact that they segregated for parental characters. The frequency of somatic hybrid production was comparable to that previously established for two sexually compatible Petunia species.     

Movements of wintering surf scoters: predator responses to different prey landscapes

The distribution of predators is widely recognized to be intimately linked to the distribution of their prey. Foraging theory suggests that predators will modify their behaviors, including movements, to optimize net energy intake when faced with variation in prey attributes or abundance. While many studies have documented changes in movement patterns of animals in response to temporal changes in food, very few have contrasted movements of a single predator species naturally occurring in dramatically different prey landscapes. We documented variation in the winter movements, foraging range size, site fidelity, and distribution patterns of a molluscivorous sea duck, the surf scoter (Melanitta perspicillata), in two areas of coastal British Columbia with very different shellfish prey features. Baynes Sound has extensive tidal flats with abundant clams, which are high-quality and temporally stable prey for scoters. Malaspina Inlet is a rocky fjord-like inlet where scoters consume mussels that are superabundant and easily accessible in some patches but are heavily depleted over the course of winter. We used radio telemetry to track surf scoter movements in both areas and found that in the clam habitats of Baynes Sound, surf scoters exhibited limited movement, small winter ranges, strong foraging site fidelity, and very consistent distribution patterns. By contrast, in mussel habitats in the Malaspina Inlet, surf scoters displayed more movement, larger ranges, little fidelity to specific foraging sites, and more variable distribution patterns. We conclude that features associated with the different prey types, particularly the higher depletion rates of mussels, strongly influenced seasonal space use patterns. These findings are consistent with foraging theory and confirm that predator behavior, specifically movements, is environmentally mediated.     

A remarkable range disjunction recorded in <Emphasis Type="Italic">Metarungia pubinervia</Emphasis> (<Emphasis Type="Italic">Acanthaceae</Emphasis>)

Summary  The first occurrence of the genus Metarungia Baden (Acanthaceae) in west Africa is recorded with the discovery of an isolated population of the widespread eastern African taxon M. pubinervia (T. Anderson) Baden in eastern Nigeria. The conservation status of this species is discussed.     

Abiotic factors control invasion by Argentine ants at the community scale

1. A prominent and unresolved question in ecology concerns why communities differ in their susceptibility to invasion. While studies often emphasize biotic resistance, it is less widely appreciated how the physical environment affects community vulnerability to invasion. 2. In this study we performed field experiments to test how abiotic variation directly and indirectly influences the extent to which Linepithema humile Mayr (Argentine ants) invade seasonally dry environments in southern California. 3. In controlled and replicated experiments involving drip irrigation, we demonstrate (i) that elevated levels of soil moisture increased both the abundance of Argentine ants and their ability to invade native ant communities and (ii) that cessation of irrigation caused declines in the abundance of Argentine ants and led to their withdrawal from previously occupied areas. 4. Because drip irrigation stimulated plant growth, in an additional experiment we manipulated both soil moisture and plant cover to assess the direct vs. indirect effects of added water on the abundance of L. humile. 5. Local abundance of Argentine ants increased in irrigated plots but was 38% higher in irrigated plots with plants compared to irrigated plots where plant growth was suppressed. The results of this experiment thus argue for a direct role of soil moisture in influencing Argentine ant abundance but suggest that that the indirect effects of added water may also be important. 6. Our study illustrates more generally that fine-scale variation in the physical environment can control whether communities become invaded by non-native species and suggests that an understanding of community susceptibility to invasion will be improved by a better appreciation of interactions between the biotic and abiotic environment.     

Quantitative detection of C-reactive protein using phosphocholine-labelled enzyme or microspheres

C-reactive protein (CRP) is a positive, acute-phase protein. Plasma levels rise dramatically in response to tissue injury or inflammation and fall rapidly after recovery or treatment. Antibody-based human CRP test systems do not readily detect CRP from other animals due to the species specificity of antibodies directed against human CRP. Thus, generic systems for CRP detection, based solely on the interaction between CRP and phosphocholine (PC), have been developed. PC-bovine serum albumin (PC-BSA) conjugates were produced and either labeled with horseradish peroxidase to facilitate CRP detection in a CRP enzyme-linked sorbent assay (ELSA) or coupled to carboxy-modified microspheres to facilitate the nonenzymatic, turbidimetric detection of CRP. The CRP-ELSA is a competitive assay, where the total assay time is 45 min, the assay sensitivity is 1.06 mg/L CRP, and the dynamic range of the assay is 0-500 mg/L. When PC-BSA conjugate is covalently coupled to carboxylated microspheres, agglutination occurs in the presence of CRP, the extent of which depends on the quantity of CRP present in the sample. Total assay time is 5 min with a dynamic range of 25-500 mg/L. Both assay formats are capable of accurately detecting human CRP and the CRP-ELSA can detect canine CRP as a disease state indicator.     

Quantitative Circulatory Physiology: an integrative mathematical model of human physiology for medical education

We have developed Quantitative Circulatory Physiology (QCP), a mathematical model of integrative human physiology containing over 4,000 variables of biological interactions. This model provides a teaching environment that mimics clinical problems encountered in the practice of medicine. The model structure is based on documented physiological responses within peer-reviewed literature and serves as a dynamic compendium of physiological knowledge. The model is solved using a desktop, Windows-based program, allowing students to calculate time-dependent solutions and interactively alter over 750 parameters that modify physiological function. The model can be used to understand proposed mechanisms of physiological function and the interactions among physiological variables that may not be otherwise intuitively evident. In addition to open-ended or unstructured simulations, we have developed 30 physiological simulations, including heart failure, anemia, diabetes, and hemorrhage. Additional stimulations include 29 patients in which students are challenged to diagnose the pathophysiology based on their understanding of integrative physiology. In summary, QCP allows students to examine, integrate, and understand a host of physiological factors without causing harm to patients. This model is available as a free download for Windows computers at http://physiology.umc.edu/themodelingworkshop.     

YC-1, a benzyl indazole derivative, stimulates vascular cGMP and inhibits neointima formation

The pathobiologic process of arterial stenosis following balloon angioplasty continues to be an enigmatic problem in clinical settings. This research project investigates the ability of YC-1, a benzyl indazole derivative that sensitizes sGC/cGMP, to stimulate endogenous cGMP and attenuate balloon injury-induced neointima (NI) formation in the rat carotid artery. Northern and Western blot analyses revealed enhanced acute expression of iNOS and inducible heme oxygenase (HO-1) mRNA and protein in the injured artery. The contralateral uninjured artery also demonstrated acute HO-1 mRNA and protein induction without detectable iNOS expression. Perivascular application of YC-1 immediately following injury significantly stimulated acute vessel wall cGMP compared to untreated controls. YC-1 treated sections demonstrated significant reduction in NI area (-74%), NI area/medial wall area (-72%), and NI thickness (-76%) 2 weeks post-injury. These results directly implicate YC-1 as a potent new therapeutic agent capable of reducing post-angioplasty stenosis through endogenous CO- and/or NO-mediated, cGMP-dependent processes.