Intra-Specific Variation in the Common Shiner, Notropis cornutus frontalis (Agassiz) from Minnesota and South Dakota

The voluminous literature relating to intra-specific variations in fishes has been reviewed by Hubbs (1934, 1940), Tanning (1952), Lindsay (1953) and others. A majority of the workers have supported the interpretation that the variation is influenced by various environmental factors, primarily the temperature during the pre-fry stages of development. Certain of the meristic characters which show such variability have been generally used in identifying various races of minnows. If such characters as the number of anal fin rays or scales in the lateral line are easily influenced by the environment, their usefulness in defining races is certainly open to question. However, if they are little influenced by environmental conditions, then their usefulness is not subject to such criticism. Support for the latter view can be found in certain experimental studies (Gabriel 1944, Heuts 1949)

Cellular localisation of polyphenol oxidase and peroxidase activity in Litchi chinensis Sonn. pericarp

Cellular localisation of visual browning and oxidative activity studies were conducted to determine the relative significance of polyphenol oxidase (PPO) and peroxidase (POD) activities during pericarp browning. Pericarp browning was first observed on the protuberance apices and subsequently extended uniformly over the entire pericarp surface. Anatomically, browning was highly localised and restricted to the epicarp and the upper mesocarp. PPO and POD activities were highest in the epicarp, with progressively less activity in both the mesocarp and endocarp. In situ localisation of oxidative activity using tissue blots confirmed high epicarp PPO activity. POD activity, although primarily restricted to mesocarp vascular tissue, was also detected in the epicarp. We believe that litchi pericarp browning is due to highly localised oxidative activity in the epicarp and upper mesocarp. As PPO and POD activities were significantly higher in this tissue and browning was not observed when both enzymes were selectively inhibited, it is postulated that both PPO and POD activities are associated with litchi pericarp browning. The current theory that litchi pericarp browning is only caused by PPO activity needs to be re-appraised to determine the relative role of POD activity

Substrate stiffness and VE-cadherin mechano-transduction coordinate to regulate endothelial monolayer integrity.

The vascular endothelium is subject to diverse mechanical cues that regulate vascular endothelial barrier function. In addition to rigidity sensing through integrin adhesions, mechanical perturbations such as changes in fluid shear stress can also activate force transduction signals at intercellular junctions. This study investigated how extracellular matrix rigidity and intercellular force transduction, activated by vascular endothelial cadherin, coordinate to regulate the integrity of endothelial monolayers. Studies used complementary mechanical measurements of endothelial monolayers grown on patterned substrates of variable stiffness. Specifically perturbing VE-cadherin receptors activated intercellular force transduction signals that increased integrin-dependent cell contractility and disrupted cell-cell and cell-matrix adhesions. Further investigations of the impact of substrate rigidity on force transduction signaling demonstrated how cells integrate extracellular mechanics cues and intercellular force transduction signals, to regulate endothelial integrity and global tissue mechanics. VE-cadherin specific signaling increased focal adhesion remodeling and cell contractility, while sustaining the overall mechanical equilibrium at the mesoscale. Conversely, increased substrate rigidity exacerbates the disruptive effects of intercellular force transduction signals, by increasing heterogeneity in monolayer stress distributions. The results provide new insights into how substrate stiffness and intercellular force transduction coordinate to regulate endothelial monolayer integrity

Revised Distribution Records of Some Minnesota Fishes, With Addition of Two Species to the Faunal List

Recent collections of fishes in Minnesota hove resulted in the addition of two species, Moxostoma carinatum (Catostomidae) and Ammocrypta asprella (Percidae), to the state\u27s inland faunal list. Additional information on the distribution of 11 other species (Minytrema melanops, Hybopsis x-punctata, Opsopoeodus emiliae, Dionda nubiloa, Notropis amnis, Notropis texanus, Notropis umbratilis, Pimephales vigilax, Lepomis humilis, Etheostoma asprigene, ond Etheostoma microperca) is presented . Collections in large rivers are responsible for several new distribution records, and further sampling in such habitats should lead to further discoveries

The Summer Standing Crop, Growth and Distribution of Chironomus plumosus, in Lake Itasca, Minnesota

During the period 15 June to 3 September 1965, 626 Ekman dredge hauls were made in Lake Itasca, Minnesota. The numbers and weights of Chironomus plumosus L. at 6 m, 7 m, 8 m, Siefert\u27s Hole (9.5 - l 0.4 m), and Peace Pipe Vista (11.5 - 13.7 m) depression were determined. In addition, the numbers and weights of several other benthic dipteran larvae, Cryptochironomus, Palpomyia, and Procladius, normal associates of C. plumosus, were determined. A loss of 98,407 larvae/ha/day occurred in the 6-9 m stratum during the 12 weeks. There was a decrease in numbers of larvae of 79.3% and 84% at Siefert\u27s Hole and Peace Pipe Vista depression, respectively. The summer decrease in biomass was 4.23 kg/ha/day in the 6-9 m stratum, 1.72 kg/ha/day in Siefert\u27s Hole, and 0.98 kg/ha/day in the Peace Pipe Vista depression. The individual larvae were gaining weight during the 12 week period when the biomass was decreasing. The ANOVA of numbers of larvae during the last seven weeks of the sampling period showed significant effects of depth and time on numbers, but no significant interaction. Fisher\u27s coefficient of dispersion was used to determine the distributional patterns of larvae al the various sampling depths; few collections varied significantly from random distribution, in several samples from Siefert\u27s Hole and the Peace Pipe Vista depression the larvae showed a clumped distribution. The number of larvae surviving to 3 September were estimated to represent a potential pupal crop of 87.31 kg/ha in the 6-10.5 m stratum

Lanthanides and other spectral oddities in a Centauri

Context: There is considerable interest in the helium variable a Cen as a bridge between helium-weak and helium-strong CP stars. Aims: We investigate Ce III and other possible lanthanides in the spectrum the of hottest chemically peculiar (CP) star in which these elements have been found. A {Kr II line appears within a broad absorption which we suggest may be due to a high-level transition in C II. Methods: Wavelengths and equivalent widths are measured on high-resolution UVES spectra, analyzed, and their phase-variations investigated. Results: New, robust identifications of Ce III and Kr II are demonstrated. Nd III is likely present. A broad absorption near 4619[A] is present at all phases of a Cen, and in some other early B stars. Conclusions: The presence of lanthanides in a Cen strengthens the view that this star is a significant link between the cooler CP stars and the hotter helium-peculiar stars. Broad absorptions in a Cen are not well explained.Comment: Research Note accepted by Astronomy and Astrophysics; 4 pages, 4 Figs. 2 Table

New Distributional Records of Some Minnesota Fishes

Minnesota is almost unique in that its waters drain by three divergent courses: the Red River to the Arctic, the Great Lakes to the Gulf of St. Lawrence and the Mississippi River to the Gulf of Mexico. The close proximity of the headwaters of these several drainages present opportunities for certain species to move from one basin to another. Species restricted to the Arctic basin have their southern limits in northern and western Minnesota. Many eastern and southern species have their northern and western limits within the state. In spite of the fact that intensive collecting has been carried on since 1890 by various workers new records or range extensions are made each year