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THS DEPARTISNT OF THs HOSPITAL

Dr. Rivers, Director

STUDIZS ON PNSUMOCOCCI. THS CAUSATIVS ACENT OF LOBAR PNSUMONIA
Dr. Avery and associates.

Dr. Avery and his associates have continued their work on the
transformation of one type pneumococcus to another. Results of previous
work showed that the essential transforming substance is desoxyribonucleic
acid. If, under vroper conditions, desoxyribonucleic acid derived from a
smooth Type III pneumococcus is added to a culture of a rough variant of
Type I pneumococcus, this variant becomes a smooth Type III pneumococcus.
In addition to the essential transforming agent, other factors are required
for transformation. In last year's report was a description of work on the
accessory factors. At that time it was stated thet rough variants, in
order to be transformed, had to be clumped either by agglutinating anti-
bodies or by some physical means; that a dialyzable factor in serum is
essential; and, finally, that a globulin factor, which may be obtained
from serum or certain organs, is required.

Work on the accessory factors has been continued during the past
year and it has been found that sodium pyrophosphate can act as the dialyz—
able factor and that the nondialyzable factor previously thought to be
globulin is actually albumin. Evidence that it is albumin instead of
f@lobulin has been obtained by using exceedingly small amounts of crystal- _
line albumin obtained by methods recently described by Cohn of Harvard.

As little as 300 micrograms of purified serum albumin per cubic centimeter
of culture medium can under the proper conditions be the decisive factor

determining prompt and typical transformation.
al

The idea, previously mentioned, that globulin instead of albumin
was one of the accessory fectors for transformation can be explained in the
following manner. Before testing human sera or serous fluids for their
ability to support transformation, it as customary to subject them to
heating (60°C. for 30 minutes) at their normal slightly alkaline reaction.
This was done in order to inactivate a serum enzyme, desoxyribonuclease,
which would otherwise depolymerize and thus destroy the transforming
activity of the specific nucleic acid present in the transforming system.
It is not necessary to heat purified serum albumin for this vurpose, but
when it is heated under these conditions, the protein becomes more readily
precipitable at lower concentrations of salt. Accordingly, it appears not
unlikely that the activity previously observed in globulin fractions of
the serum may have been due to such altered albumin.

Pneumococei exhibit mariced variability in colonial forms covering
a wide range of differences in contour, morphology and surface topography.
The colonial variants disvlay all degrees of smoothness and roughness from
the glistening mucoid to the extremely granular and pebbled~surfaced colony.
These physical features are in many instances reflected in recognized
differences in biochemical and vhysiological properties of the cells.
Considerable information is available with regard to alterations in the
antigenic structure, serological behavior and virulence associated with
these colonial changes. It seemed possible to Dr. Avery and his associates
that the principles and techniques of transformation might afford a
specific means of investigating the hereditary basis of this phenomenon.
Work along these lines has vrogressed favorably and findings to date are
summarized in the next two paragranhs.

The property of extreme roughness (ER) as opposed to moderate

 
been

22
roughness (MR) is apparently due to the lack of a factor or factors which
can be experimentally introduced into the cells by the techniques of
transformation. The I factor is present in the desoxyribonucleic acid
fraction of the moderately rough variant and of smooth Type III organisms
as well. The factor MR, which determines the change from extreme to
moderate roughness, can be introduced independently of the SIII factor.
Indeed, the &R forms cannot be transformed to encapsulated Tyoe III
organisms until they have first been converted into MR cells, that is,
the MR factor must be introduced first, the reaction being ER-~> MR--SSIII.

This form of analysis is being pursued with three objectives
in mind. First, it is hoped that some information may be gained on the
nature of "competence", that property of cells which determines their
capacity to respond to a given specific stimulus or factor in transforma~
tion. Second, such experiments may make possible further analysis of the
nature of the specificity of the transforming substances. Third, the
demonstration that two factors, one for moderate roughness (MR), the other
for synthesis of capsular polysaccharide (SIII), each coexisting in the
same preparation of nucleic acid, can be selectively taken up by pneumo~
coccal cells and independently bring about development of the correspond-
ing traits, justifies the hope that the pneumococcal cell may prove a
delicate tool for the study of many hereditary characters at a biological

level heretofore unrealized by geneticists.

ACUTS_AND CHRONIC DISORDERS OF THES LIVER
Dr. Hoagland and his associates.
As stated in previous reports, Navy vatients with infectious
hepatitis or epidemic jaundice were admitted to the Rockefeller Hospital

for treatment and study. Hention was made in last year's report that