Sampling errors in anchovy egg abundance estimates using the PAIROVET net

A replicate haul experiment was carried out using the verticallytowed PAIROVET net in an area of high abundance of anchovy eggsin the Bay of Biscay. The main aim of the experiment was tocompare the performance of ships of different size working inthe same area. In addition, we tested the performance of thePAIROVET net and the deployment methodology used to sample anchovyeggs for biomass assessment purposes. We concluded that underthe experimental conditions experienced in this cruise, differentships yield similar performances of the vertically towed PAIROVETnet if the methodology is kept similar. The ANOVA suggests thatthe systematic central sampling (SCS) scheme currently in usefor the Bay of Biscay anchovy biomass estimations (one stationout at 3 miles) adequately represents the surrounding area alongthe transect line. The among-station component of variance withinthe unit sampling area of the current SCS turned out to be comparableand, in some cases, smaller than the within-station variance.Consequently, the spatial design of the SCS adopted during routinesurveys appears to be a reliable strategy for sampling anchovyeggs in areas of high egg abundance, as in this experiment.In addition, it ensures fairly independent data units. In thearea of the experiment, the most disperse egg stages (like 2-and 3-day-old eggs) show a larger within-station component ofvariance than the spatial component of variance within the rectanglesof the current SCS. This suggests that for these stages, thesampling can still be improved cheaply by increasing the precisionof egg abundance estimates per station with larger sample sizes,without changing the spatial sampling scheme or the number ofstations. However, the benefits of this strategy will hardlyaffect the precision of the 1-day-old egg estimates becauseof their patchy distribution.     

Les sporophylles de Lepidodendron dissitum Sauveur, 1848

One specimen belonging to the arborescent lycopod stem species Lepidodendron dissitum SAUVEUR was found in connection with sporophylls named Lepidophyllum anthemis (KÖNIG) JONGMANS, species of a great stratigraphical and geographical range during the Upper Carboniferous, and specially abundant in the Spanish Stephanian. These two parts from the same plant are described and discussed in detail.     

The equilibration of lead between blood and milk of lactating rabbits

The basal concentration of lead in milk of lactating rabbits is approximately 65% that of blood. After the intravenous injection of lead acetate, the lead concentration in blood peaked at 1 hour and thereafter declined rapidly, reaching a plateau within 5 days. In contrast, the lead concentration in milk continuously increased with time and by 7.5 days (maximum) exceeded that of blood 8-fold. The possibility that passage of Pb⁺⁺, like Ca⁺⁺, Sr⁺⁺ and other ions from blood to milk occurs against a concentration gradient is suggested. The consequences of this observation on subclinical lead poisoning in neonates is discussed.     

Purification and properties of a 3'-phosphoryl former endodeoxyribonuclease from eggs of Asterias forbesi.

A DNA endonuclease has been purified from eggs of Asterias forbesi by a simple four-step-purification procedure. The purified enzyme is at least 96% pure and is free of phosphatase, phosphodiesterase, and RNase. It has a pH optimum of 6.5 and does not require divalent cations. The enzyme produces 3'-phosphoryl and 5'-hydroxyl end groups. The products of exhaustive hydrolysis can be grouped in two fractions. The first fraction, 40%, contains a small amount of mononucleotides and di-, tri-, tetra-, penta-, and hexanucleo-tides. The second fraction, 60%, contains oligonucleotides larger than hexanucleotides.     

Competitive inhibition of the auxin-induced elongation by α-D-oligogalacturonides in pea stem segments

Branca, C, De Lorenzo, G. and Cervone, F. 1988. Competitive inhibition of the auxin-induced elongation by α-D-oligogalacturonides in pea stem segments. - Physiol. Plant. 72: 499–504.
α-D-galacturonide oligomers (OG) were prepared by partial hydrolysis of sodium polypectate with an homogeneous Aspergillus niger endopolygalacturonase (EC 3.2.1.15). OG, obtained after digestion for 10, 20, 30, 60, 120 min and 24 h, were assayed for their ability to interfere with the IAA-induced elongation of pea ( Pisum sativum L. cv. Alaska) stems. Maximum inhibiting activity was exhibited by oligomers with an approximate degree of polymerization higher than 8. Inhibition by longer OG was much lower, and the products of the 24 h digestion and the unhydrolysed polypectate were ineffective. The addition of OG to pea stems caused a parallel shift to the right of the IAA dose-effect curve. The shift depended on the amount of OG used, showing that oligogalacturonides behave as competitive antagonists of IAA. The presence of OG caused the disappearance of the second maximum of the elongation rate and reduced the first maximum. OG were also tested for their ability to inhibit IAA-induced ethylene evolution of pea stem segments. Maximal inhibition was obtained with OG of the same size as those that interfered with IAA-induced elongation. Inhibition of the auxin action seemed to be specific as OG did not interfere with the activity of gibberellic acid (GA₃) or kinetin. It was concluded that oligogalacturonides strongly interfere with the activity of IAA, although they are by themselves incapable to influence the elongation of pea stem segments directly.