Fisheries. Population of origin of Atlantic cod

Most of the world's cod (Gadus morhua) fisheries are now tightly regulated or closed altogether. Being able to link individual fish to their population of origin would assist enormously in policing regulations and in identifying poachers. Here we show that microsatellite genetic markers can be used to assign individual cod from three different populations in the northeastern Atlantic Ocean to their population of origin.     

Contributions of microbial biofilms to ecosystem processes in stream mesocosms

In many aquatic ecosystems, most microbes live in matrix-enclosed biofilms and contribute substantially to energy flow and nutrient cycling. Little is known, however, about the coupling of structure and dynamics of these biofilms to ecosystem function. Here we show that microbial biofilms changed the physical and chemical microhabitat and contributed to ecosystem processes in 30-m-long stream mesocosms. Biofilm growth increased hydrodynamic transient storage-streamwater detained in quiescent zones, which is a major physical template for ecological processes in streams-by 300% and the retention of suspended particles by 120%. In addition, by enhancing the relative uptake of organic molecules of lower bioavailability, the interplay of biofilm microarchitecture and mass transfer changed their downstream linkage. As living zones of transient storage, biofilms bring hydrodynamic retention and biochemical processing into close spatial proximity and influence biogeochemical processes and patterns in streams. Thus, biofilms are highly efficient and successful ecological communities that may also contribute to the influence that headwater streams have on rivers, estuaries and even oceans through longitudinal linkages of local biogeochemical and hydrodynamic processes.     

Minimum Sum of Squares Clustering in a Low Dimensional Space

Clustering with a criterion which minimizes the sum of squared distances to cluster centroids is usually done in a heuristic way. An exact polynomial algorithm, with a complexity in O(N ^p+1 logN), is proposed for minimum sum of squares hierarchical divisive clustering of points in a p-dimensional space with small p. Empirical complexity is one order of magnitude lower. Data sets with N = 20000 for p = 2, N = 1000 for p = 3, and N = 200 for p = 4 are clustered in a reasonable computing time.     

Morphometric study of the aortic body types I cell

Summary The subclavian glomus (aortic body) of New Zealand white rabbits was examined ultrastructurally using stereological morphometric analysis. The Type I cells of the glomus possess numerous electron-opaque vesicles which occupy approximately 12% of the cytoplasmic volume of the cells. The amine-containing vesicles comprise a heterogeneous population of vesicles with a mean caliper diameter of 113.5 nm. Differences in vesicle diameters may indicate the storage of different biogenic amines, different secretion or maturation states between glomera and/or additional physiological functions for the glomera.Supported by NIH Grant 5-TO1-GM793 and The University of Texas.     

Monomeric insulins obtained by protein engineering and their medical implications

The use of insulin as an injected therapeutic agent for the treatment of diabetes has been one of the outstanding successes of modern medicine. The therapy has, however, had its associated problems, not least because injection of insulin does not lead to normal diurnal concentrations of insulin in the blood. This is especially true at meal times when absorption from subcutaneous tissue is too slow to mimic the normal rapid increments of insulin in the blood. In the neutral solutions used for therapy, insulin is mostly assembled as zinc-containing hexamers and this self-association, which under normal physiological circumstances functions to facilitate proinsulin transport, conversion and intracellular storage, may limit the rate of absorption. We now report that it is possible, by single amino-acid substitutions, to make insulins which are essentially monomeric at pharmaceutical concentrations (0.6 mM) and which have largely preserved their biological activity. These monomeric insulins are absorbed two to three times faster after subcutaneous injection than the present rapid-acting insulins. They are therefore capable of giving diabetic patients a more physiological plasma insulin profile at the time of meal consumption.     

Effects of 6-hydroxydopamine on rat carotid body chief cells

Summary Administration of 6-hydroxydopamine (6-OHDA) in concentrations high enough to cause degeneration of perivascular adrenergic nerve terminals has no morphological effect on the catecholamine-storing cells of the rat carotid body. Uptake of 6-OHDA by carotid body chief cells may be more selective than that exhibited by small-intenselyfluorescent cells and other catecholamine-storing cells which are affected by 6-OHDA. Alternatively, the sustentacular cells which envelope the chief cells may provide an effective barrier against the uptake of 6-OHDA.Supported by a Grant-in-Aid from the American Heart Association (77 630) and with funds contributed in part by the Texas Affiliate.