Inactivation of Sperm by X-Radiation in HabrobraconAuthor(s): Jane MaxwellSource: Biological Bulletin, Vol. 74, No. 2 (Apr., 1938), pp. 253-255Published by: Marine Biological LaboratoryStable URL: http://www.jstor.org/stable/1537759 .

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INACTIVATION OF SPERM BY X-RADIATION IN HABROBRACON

JANE MAXWELL

(From the Marine Biological Laboratory, Woods Hole, Mass.)

Sterility of the male may be due to lack of sperm, to defective or inactivated sperm unable to fertilize the eggs or to sperm carrying dominant lethals which kill the fertilized eggs.

The wasp Habrobracon is convenient material for the study of these types of male sterility. Normally males develop from unfertilized eggs by haploid parthenogenesis, females from fertilized eggs. Ab- sence or inactivation of sperm would result in the production of no daughters and of sons equal in number to those of unmated females. If all the sperm contain dominant lethals no daughters are produced and the fecundity of the mated females is correspondingly reduced. Consequently analysis of differences in biparental ratio and in fecundity indicates the type of male sterility which has been operative.

P. W. Whiting (1937) demonstrated that treatment of sperm with X-ray dosages of 20,000, 40,000 and 75,000 r units produces at least one dominant lethal in every sperm cell. No daughters occur in the progeny and the average number of males produced per day does not equal that to be expected from virgin females, indicating that many eggs are fertilized and die. Sperm treated with 75,000 r units fertilized almost as many eggs as untreated sperm; therefore the treatment ap- parently did not cause inactivation. However, a slight increase in the average males per day from mates of males treated with 75,000 r units as compared with those from mates of untreated controls sug- gested the possibility that spermatogenesis might to some extent be stopped and sperm supply decreased.

An experimnent carried out with the X-ray equipment at the Marine Biological Laboratory, Woods Hole, Mass., July-August, 1937, was designed to test this hypothesis (Table I). One group of wild-type males (stock 32) was treated with 41,000 r units, another group with 142,000 to 143,000 r units. A third group was untreated. Each male was mated on each successive day to a different female which was

1 The author is indebted to the University of Pennsylvania for furnishing labora- tory space at the Marine Biological Laboratory during the summer of 1937, and to the Committee on Effects of Radiation on Living Organisms (National Research Council) for technical assistance furnished from a grant to Dr. P. W. Whiting.

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JANE MAXWELL

segregated for breeding. Unmated females of the same stock were segregated each day as controls. The total number of days of the egg- laying periods of all females of any one group mated on the same day is the basis of the averages of offspring per day.

It was expected that successive matings would exhaust the sperm of the treated males provided that no spermatogenesis took place after the treatment. Such exhaustion does not occur since the last matings of these males produce average males per day equivalent to those from mates of untreated males and lower than the average for the offspring of unmated females.

TABLE I

Offspring from orange-eyed females (stock 11-o) mated with untreated or with x-rayed wild-type males (stock 32) or bred unmated.

Offspring from Offspring from Offspring from untreated males 41,000 142,000 and

r males 143,000 r males Day of mating

Per Per Da Per Per Days +99 9 o cT I ays ocfcT ^ Days od^ ^ Days day y ooe day s d' day

1st............... 152 524 3.44 247 1.62 139 184 1.32 219 464 2.11 2nd ............. 136 671 4.93 203 1.49 129 257 1.99 208 368 1.76 3rd............. 145 337 2.32 116 .80 120 245 2.04 120 285 2.37 4th.............. 168 487 2.89 174 1.03 137 223 1.62 89 176 1.97 5th ............. 113 303 2.68 103 .91 120 128 1.06 41 71 1.73 6th ...... ....... 93 185 1.99 62 .67 128 112 .88 7th ..............117 302 2.58 59 .50 60 44 .73 8th.............. 100 258 2.58 87 .87 128 194 1.51 9th and 10th ...... 59 188 3.18 82 1.38 116 128 1.10

Totals from mated females ......... 1083 3255 3.01 1133 1.05 1077 1515 1.41 677 1364 2.01

Total from unmated females.... Days, 344. Males, 1073. Males per day, 3.12.

In the total averages of males per day for all the fraternities from treated, evidence is found of failure of sperm to fertilize and thus kill some of the eggs. The total average of males per day increases with increasing dosage and for 142,000 to 143,000 r units is intermediate (2.01) between the mated controls (1.05) and the unmated controls (3.12).

Inactivation of sperm following higher dosages rather than partial exhaustion of sperm supply due to partial inhibition of spermato- genesis is indicated by the fact that there is no increase in males per day from the later matings. It is probable that even much weaker dosages than those here used completely stop spermatogenesis. Thus

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INACTIVATION OF SPERM BY X-RADIATION 255

we have partial male sterility due to dominant lethals at relatively weak dosages, complete male sterility due to dominant lethals at stronger dosages, and partial sperm inactivation at very high dosages.

The average offspring per day (males) from unmated females (3.12) is less than the average offspring per day (females and males) from females mated to untreated males (4.05). This is attributed to re- cessive lethals segregating in certain fraternities summarized together in Table I. In other experiments viability of males and females has been about equal.

LITERATURE CITED

WHITING, P. W., 1937. Habrobracon as a means of testing the effectiveness of physical agents in causing mutations. Proc. Penna. Acad. Sci., 11: 50.

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