Eskil Hultin

Alkaloid-screening of swedish plants

Abstract A method is given for a semi-quantitative determination of the alkaloid concentration in dried plant material. In a screening of two hundred plants in Sweden, wild and cultivated, the following plants not previously known to contain alkaloids gave a positive reaction corresponding to an alkaloid concentration of more than 0·05 per cent of the dried plant: Linnea borealis and Valeriana sambucifolia; and, additionally, the following gave a positive reaction corresponding to at least 0·01 per cent: Armeria maritima, Bartonia aurea, Cobaea scandens, Euphrasia frigida, Galium aparine, Hemerocallis conspicua, Lonicera periclymenum, Melampyrum pratense, Odontites litoralis, Pedicularis palustris, Pedicularis silvatica, Phragmites communis, Picea abies, Pinguicula vulgaris, Platanthera bifolia, Plantago media, Polygala vulgaris, Polygonum viviparum, Rhamnus cathartica, Rhamnus frangula. Silene rupestris, Sorbus intermedia, Spergula arvensis, Spergula marginata, and Veronica officinalis. The following plants, previously reported to contain alkaloids, gave a positive reaction corresponding to more than 0·05 per cent: Ligustrum vulgare, Succisa pratensis, and Valeriana officinalis. In the plant family Scrophulariaceae ten out of nineteen species investigated gave a positive reaction corresponding to at least 0·01 per cent of alkaloids. Earlier reports indicating the presence of alkaloids in the following plants were not confirmed: Alnus glutinosa, Anthemis tinctoria, Butomus umbellatus, Calla palustris, Chamaenerion angustifolium, Corylus avellana, Euphorbia peplus, Geranium molle, Glaux maritima, Herniaria glabra, Odontites verna, Pyrola rotundifolia, and Scirpus Tabernaemontani. The present results are compared with earlier reports available from the literature.

The variability in the fertilization rate

Abstract The rate of fertilization in a mixture of eggs and spermatozoa can be characterized by the time FT 50 at which 50 per cent of the eggs are fertilized and by the standard deviation of the distribution about the 50 per cent fertilization time. The logarithms of the times, at which the individual eggs are fertilized, are—at least approximately—normally distributed about the logarithm of the 50 per cent fertilization time. The calculation of the 50 per cent fertilization time and of the standard deviation is easily made from a graph in which the probits of the percentage of fertilized eggs are plotted versus the logarithms of the times; cf. dosage-mortality curves from toxicity experiments. There are four kinds of fertilization rate variability for the eggs of Paracentrotus lividus : the occurrence of several groups of eggs with different 50 per cent fertilization times in one single female, the distribution of the eggs in one group about their 50 per cent fertilization time, the difference between females collected at the same time and place and the difference between females collected at different times and places. The rate of the development of the fertilized eggs is different for different groups of eggs. The variability in fertilizability and in fertilization rate is remarkable even in selected material of apparently the best quality available. For the various groups of eggs from 12 high quality females FT 50 varied between 7 and 135 seconds. The standard deviation for the logarithm of the fertilization time for the eggs in the various groups differed between 0,1 and 0,4. The differences between the females collected at the same time and place were not noticeably less than the differences between females collected at different times and places. The variability is thus so great that it is indispensible to check the fertilization rate of eggs intended to be used for investigations in which material of a high uniformity is desirable.

Mechanism of fertilization by rate determinations.

Abstract A theoretical interpretation is given for the influence of sperm concentration on fertilization rate: only those spermatozoa which are near the eggs have a prime influence, either chemical—as spermatozoa give off substances which have an influence upon the fertilization—or mechanical. As there is space only for a limited number of spermatozoa in the first orbit round the egg, the fertilization rate cannot incresae over a certain limit as the sperm concentration is increased. The influence of the sperm concentration n on the 50 per cent fertilization time FT50 is, according to this orbit theory, given by the following equivalent equations, which are suitable for the graphical computation of lim FT50 = the limit 50 per cent fertilization time, and of n 1 2 = the sperm concentration, at which the fertilization rate is half the limit rate at high sperm concentrations; it is possible using these equations to fit straight lines to the plottings: FT 50 = lim FT 50 + n 1 2 · ( lim FT 50 ) · 1/n; n · FT 50 = n 1 2 ( lim FT 50 ) + ( lim FT 50 ) · n, and 1/FT 50 = 1/( lim FT 50 ) −n 1 2 · 1/(n · FT 50 ). The measurements of Rothschild and Swann on Psammechinus miliaris fit the equations well. The influence of fertilization rate regulators in the sperm medium should be eliminated in experiments for the determination of lim FT50 and n 1 2 .

Degradation of starch, hydroxiethyl cellulose ether and chitosan by enzymes in spermatozoa and sperm fluid from Psammechinus and Modiola☆☆☆

Abstract The semen of Psammechinus and Modiola contains cellulase, and has also the ability of depolymerizing chitosane. The semen of Psammechinus also contains amylase, whereas Modiola was not tested in this respect. The enzymes are present both in the spermatozoa and in the suspending medium. The optimum pH for activity is for amylase about 7 and for cellulase about 6.

Fertilization rate regulators.

Abstract 1. 1. The investigation was carried out with Echinocardium cordatum on the west coast of Sweden in July and August, 1953. 2. 2. The fertilizing power of spermatozoa is removed immediately in a 0.0007 per cent solution of sodium lauryl sulphate. This makes it possible in fertilization experiments to measure decreases in the proportion of unfertilized eggs during the period after insemination. 3. 3. The proportion of fertilizable eggs is dependent upon the properties of the eggs and the spermatozoa and on any regulators that may be present. 4. 4. The fertilization rate, the probability that a given egg will be fertilized within unit time, depends on the properties of the egg and the spermatozoa and may be influenced appreciably by fertilization rate regulators. 5. 5. The individual fertilizable eggs in a group of animals in the same catch may be uniform with respect to fertilization rate, with due allowance for the statistical scatter usually found with biological material. Usually, however, the fertilization rates are highly varied. 6. 6. In measurements of the relative (or percentage) distribution of eggs of different fertilization rates, the eggs could usually be assigned to three groups: unfertilized eggs, eggs of low fertilization rate and eggs of high fertilization rate. 7. 4. Under the influence of fertilization rate regulators the proportions in which these three groups occur may be altered and the fertilization rates within the groups may be changed. 8. 8. The spermatozoa release fertilization rate regulators into the medium, which act in considerable dilution. 9. 9. Ultrafiltered sperm medium promotes fertilization in low concentrations by increasing the proportions of fertilizable eggs and rapidly fertilized eggs and by increasing the fertilization rate of rapidly fertilized eggs. If a certain optimal concentration of ultrafiltrate is exceeded, inhibitory effects appear. 10. 10. The fraction of the sperm medium precipitable with tannic acid promotes fertilization in low concentrations. If, however, an optimal concentration is exceeded, an inhibitory action becomes evident. 11. 11. In the study of fertilization rate regulators from sperm, account must be taken of the amounts of regulators accompanying the spermatozoa in their medium. It may be advantageous to employ washed spermatozoa. 12. 12. Ultrafiltered sperm medium in considerable dilution can retard the ageing of the sperm. 13. 13. Ultrafiltered sperm medium contains a low-molecular fertilizatiom promoting substance which is soluble in a mixture of ether and petroleum-ether.

The influence of antibodies upon the fertilization rate

Abstract The present authors orbit hypothesis for the fertilization mechanism implies that fertilization rate increases with increased number of spermatozoa in the first orbit nearest to an egg and has a limit value which is attained only if the first orbit is completely filled up. This hypothesis has been expanded to the case in which the egg surface has been pretreated with an inhibitor, e.g. antibodies; spermatozoa close to those parts of the egg surface which have reacted with the inhibitor do not contribute to the fertilization rate. The result from experiments with the sea urchin Paracentrotus lividus are in agreement with the orbit hypothesis. At constant sperm concentration, if there is no correlation between the tendency to react with antibodies and the susceptibility to fertilization initiation for various parts of the egg surface, the following relationship is valid between half fertilization period FT50, half fertilization period in absence of antibodies (FT50)a = 0, amount of antiserum a, number of eggs ne, and limit amount of antiserum per egg lim a n e , at which the fertilization is just completely inhibited: 1/FT 50 = 1/(FT 50 ) a = 0 − (1/FT 50 ) a = 0 · lim a n e · a n e . If various parts of the egg surface have different susceptibilities to fertilization initiation and different tendencies to react with antibodies, and if these two qualities are correlated, the value of the expression (1 − (FT 50 ) a = 0 /FT 50 )/ ( a n e ) for various values of a n e can be expected to show a maximum or minimum value, provided that the differences between various parts of the egg surface and the correlation are high enough compared to the accuracy by which fertilization rates can be measured. No significant maximum or minimum was noticed in two experimental series with Paracentrotus lividus, possibly because the anti-egg serum used contained several antibodies which may have counter-acted each other in this respect or because the number of experiments was not sufficient to give significance.