close

Вход

Забыли?

вход по аккаунту

?

Chromosome variability in the Lemuridae.

код для вставкиСкачать
Chromosome Variability in the Lemuridae '
J. EGOZCUE
Department of Genetics, Oregon Regional Primate
Research Center, Beaverton, Oregon
Chromosome studies have been conducted in Lemur catta, L. macaco,
ABSTRACT
L. mongoz, L. fztlvus fulvus, and a hybrid L. fulvus fulvus x L. fulvus albifrons. Comparative analysis shows that inter- and intraspecific chramosome variability is a common finding in Lemurs. The Lemuridae are divided into three groups according to the
characteristics of their chromosome complement. A reclassification of L. catta with
the Hapalemurs is suggested, based on chromosomal and nonchromosomal data.
Some years ago (Chu and Swomley, '61 ;
Chu and Bender, '61), chromosome studies
were published on several species of
Lemurs, including L. catta, L. fulvus, L.
variegatus, L . macaco, Hapalemur griseus,
and Microcebus murinus. Interspecific
chromosome variability was found to be
the rule for the genus, the chromosomes
ranging in number from 44-66, but intraspecific variability was seen only in L.
fulvus and H . griseus.
Based on these studies, a three-group
division of the Lemurine lemurs was proposed: the first composed of the Hapalemurs; the second, of L. cutta, 1,.mongoz,
L. fuluus rufus, and L. fuluus albifrons;
the third, of L. fuluus fulvus, L. variegatus,
L. macaco, and a new subspecies, L. SQ.,
which resemble the brown lemurs (Chu
and Swomley, '61; Bender and Chu, ' 6 3 ) .
We report here our studies on L . catta,
L. macaco, L. mongoz mongoz, L . fulvus
fulvus, and a hybrid, L. fulvus fuluus x
L. fulvus albifrons. The results show that
chromosome variability is even more widespread among the Lemuridae than was
formerly supposed and suggest that a revision of the genus Lemur is in order.
MATERIALS AND METHODS
Two female L. catta, three male and
three female L. macaco, one male and
seven female L. mongoz, two male and one
female L. fuluus fulvus, and one hybrid,
L. fulvus fulvus x L. fulvus albifrons, were
used i n this study. Blood (Egozcue and
Vilarasau de Egozcue, '66) and kidney
cultures (Melnick, '66; Hagemenas and
Egozcue, in preparation) were set up for
Am. J. PHYS.ANTHROP.,26: 341-348.
chromosome studies, incubated for three
days (blood) or two weeks (kidney) at
37"C, and chromosome preparations made
up according to a technique described by
us (Egozcue and Vilarasau de Egozcue,
'66).
Micrographs were taken at 1000 X and
the karyograms constructed from metaphase prints at 2000 X.
TABLE 1
Species
Specimens
Chromosomes
Male Female
2n
L e m u r catta
-
L.macaco
3
3
44
L. mongoz
1
7
58
L.fulvus fulvus
2
1
58
Hybrid L . fulvus
fUlV7LS x L .
fulvus albifrons
1
-
58
2
56
RESULTS
Most of the metaphases in the preparations were normal and diploid. The chromosome number turned out to be 2n=56
in L . catta, 2n=44 in L. macaco, and
2n=58 in all other animals studied (table
1).In L. mongoz, of 232 cells counted, 186
had 58 chromosomes; in L. fulvus fulvus,
of 95 cells counted, 86 had 58 chromosomes; and in the hybrid, of 48 cells
counted, 42 had 58 chromosomes.
IPublication no. 214 of the Oregon Regional Primate Research Center, supported in part by Grant
FR 00163-07 from the National Institutes of Health.
341
342
J. EGOZCUE
The chromosomes were paired and arranged visually in order of decreasing size.
The sex chromosomes were determined by
elimination in the males. The chromosome
complement of L. catta is composed of four
pairs of metacentric chromosomes, three
pairs of submetacentrics and 20 pairs of
acrocentrics; the sex chromosomes are
acrocentric (fig. 1). Our results differ
somewhat from those previously reported
(Chu and Swomley, '61). There are in the
complement one more pair of metacentric
and submetacentric chromosomes and two
Iess pairs of acrocentrics. Our results in
L. macaco are identical to those of Chu
and Bender ('61) (fig. 2). The chromosome complement is composed of six pairs
of metacentrics, four pairs of submetacentrics and 11 pairs of acrocentrics; the
X chromosome is the longest acrocentric,
Fig. 1
the Y a very small acrocentric. The chromosome complements of L. mongoz, L.
fulvus fuluus and the hybrid (figs. 3,4,5)
are composed of two pairs of submetacentric chromosomes (pairs no. 1 and 2) and
26 pairs of acrocentrics. The X chromosome is the longest acrocentric, similar in
size to pair no. 3. The Y chromosome is
the smallest acrocentric. The only individually identifiable pairs are no. 1 and 2;
both are submetacentric and differ considerably in size from one another.
In the complement of all Lemurs studied
by us, two pairs of chromosomes bear a
rather long acromatic region in the midproximal third of the long arms (fig. 1, 5).
The size of the chromosomes makes its visualization difficult. These pairs are found,
by size, in positions ranging from no. 1618 for the long pair, and from no. 18-20
Chromosome complement of a female L. catta.
CHROMOSOMES OF L E M U R I D A E
Fig. 2
343
Metaphase of a female L. macaco.
for the short one. In the karyograms, we
opted to position them according to size
rather than to assign a definite position
€or each of them.
DISCUSSION
A comparison of all the Lemuridae
studied (table 2) reveals that there is a
wide range of variability in their chromosome numbers. Intraspecific variability is
found in L. mongoz mongoz (2n=58,
2n=60) and in L. fulvus albifrons
(2n=58, 2n=60), as well as in L. fulvus
fulvus (2n=58, 2n=48). The type of chromosome variability is the same for the
mongoose lemurs and the white-fronted
lemurs but quite different for L. fulvus
fulvus. Our specimens of L. m o n g m have
one less small pair of acrocentric chromosomes than the ones studied by Chu and
Swomley ('61).
There is a striking difference between
our counts in L. fulvus fulvus and the ones
by Chu and Swomley ('61). While the
karyotype of our animals is the same as
in L. mongoz and L. fulvus albifrons and
almost identical to that of other L. mongoz
and L. fulvus rufus, the karyotype of the
two animals described by Chu and Swomley ('61) is closer to the type found in
L. variegatus and L. macaco.
The results in the hybrid L. fulvus f u L
vus x L . fulvus albifrons support our count
of 2n=58 for L. fulvus fulvus and suggest that the same chromosome number
and morphological characteristics (fig. 5)
344
J. EGOZCUE
Fig. 3
Chromosome complement of a female L. mongoz.
should be found in L. f u l v u s albifrons,
since half of the complement is contributed by each of the parents and no differences were found in the chromosome complement of the hybrid.
On the grounds of their results, Chu and
Swomley ('61) and later Bender and Chu
('63) suggested that the Lemuridae be divided into three groups: (1) Hapalemurs;
(2) L. catta, L. mongoz, L. fulvus r u f u s ,
and L . f u l v u s albifrons; (3) L. f u l v u s fulvus, L. variegatus, L. macaco, and L. s p .
The data obtained in our studies indicate that a revision of these groups is in
order without, however, altering their basic
structure. The first group would consist
of the lemurs with a diploid number of
2n=60 or 2n=58, with no metacentric
chromosomes and with a significant predominance of acrocentrics. It would include the two subspecies of L. mongoz, the
subspecies of L. f u l v u s f u l v u s studied by
us, L. fulvus r u f u s , and L. fulvus albifrons.
The species with a diploid number
around 46, with a high number of metacentric and acrocentric chromosomes,
would form the second group. These are
L. f u l v u s fulvus, L. variegatus, and L.
macaco. It is rather surprising that while
most subspecies of L. fulvus have firstgroup type karyotypes, a single subspecies
of L. fulvus fulvus should have a different
chromosome complement, especially when
other animals supposedly belonging to the
same subspecies have first-group karyotypes like all other fulvus lemurs.
CHROMOSOMES O F LEMURIDAE
345
Fig. 4 Chromosome complement of a female L . fuZvus fulvus.
The third group would be composed of
the Hapxlemurs.
L. catta is a rather special case. Bolwig
('60) suggested that it be classified as a
new genus, Odorlemur catla, based upon
analysis of the brachial glands, the antebrachial organs (carpal glands), and the
associated spurs of the animal. Affolter
('38), in a description of the brachial organs of Hapalemur griseus, points out the
close res,emblance between such organs in
Hapalemur and L. catta, although he does
not think that this means they are closely
related. Montagna and Yun ('62), in a detailed histological, histochemical, and anatomical study of the dermal and carpal
glands and organs of L. catta, find many
resemblances to similar structures in Hapalemur. .Buettner-Janusch ('63) on these
grounds states that if ever they had t o be
reclassified, L. catta should be mare logically placed in a taxon with Hapalemur.
Based on chromosomal evidence, we
suggest that L. catta be included in the
Hapalemur group, characterized by a chromosome number around 56, with a low
count of both metacentric and submetacentric chromosomes and a predominance
of the acrocentric.
The new species of lemur, L. sp., described by Chu and Swomley ('61) is chromosomally closer to the Hapalemur group
although it has the general morphological
characteristics of L. fuluus. As only one
animal has been studied, we believe that
further studies are needed before any definitive classification of this possibly new
species can be made; it may prove to be
only a case of individual variability.
Thus, the three groups would be: ( 1 )
L. mongoz and L. fuZuus; (2) L. uariegatus
and L. macaco, with the inclusion of the
specimens of L. fuluus fuluus with a dip-
Fig. 5
Chromosome complement of a male hybrid L. fulvus fulvus x L. fulvus albifrons.
TABLE 2
Species
Common name
Chromosomes
Specimens
Reference
~~
Male Female
2n
M
S
A
X
Y
60
0
4
54
A
A
ChuandSwomley,’61
0
4
52
A
A
Thisreport
~
Lemur mongoz
L. mongoz
L. fulvus
L . fulvus fulvus
L. f U l V U S T U f U S
L. fulvus albifrons
Hybrid L. fulvus
fulvus x L.
fulvus albifrons
L. fulvus fulvus
Mongoose
lemur
2
3
Mongoose
lemur
1
7
Brown
lemur
...... 1
Brown
lemur
2
1
Red-fronted
lemur
2
White-fronted
lemur
1
1
L. macaco
L. macuco
L. s p .
L. catta
L. catta
Hapalemur
griseus griseus
H . griseus
olivaceus
1 Not
stated.
(58)
Chiarelli, ’61
2
58
0
4
52
A
A
Thisreport
GO
0
4
54
A
A
ChuandSwomley,’Gl
60
0
4
54
A
A
ChuandSwomley,’61
58
0
4
52
A
A
Thisreport
48
10 6
30
A
A
ChuandSwomley,’Gl
46
14 4
26
M
A
Chu andSwomley,’61
Brown
lemur
L. variegatus
58
Ruffed
lemur
Black
lemur
Black
lemur
Ringtail
lemur
Ringtail
lemur
Gray gentle
lemur
2
Tentative.
1
1
1
1
1
44
12 8
22
A
A
ChuandBender,’Gl
3
1
3
44
52
12 8
8 4
22
38
A
M
A
A
Thisreport
Chu andSwomley,’61
56
6
4
44
A
A
Chu andSwomley,’Gl
2
56
8
6
40
A
A
Thisreport
1
54
4
6
42
A
A
Chu andSwomley,’61
1
58
2
4
52
-
-
Chu andSwomley,’61
2
1
CHROMOSOMES OF LEMURIDAE
loid number of 2n=48; ( 3 ) L. catta and
Hapalemur.
Further investigation with more animals
may disclose new cases of chromosome
variability in the Lemuridae.
LITERATURE CITED
Affolter, M. 1938 Lcs organes cutanks brachiaux d’HapaZemur griseus. Bull. Acad. Malgache.
Tananarive, 20: 77-100.
Bender, M. A., and E. H. Y. Chu
1963 The
chromosomes of Primates. In: Evolutionary and
Genetic Biology of Primates. J. BuettnerJanusch, Ed. Academic Press, New York.
Bolwig, N.
1960 A comparative study of the
behaviour of various lemurs. Mem. Inst. Sci.
Madagascar, Ser. A: Biologic Anirnale, 14:
205-21 7.
Buettner-Janusch, J. 1963 An introduction to
Primates. In: Evolutionary and Genetic Biology
of Primates. J. Buettner-Janusch, Ed. Academic
Press, New York.
347
Chiarelli, B. 1961 Cited by M. A. Bender and
E. H. Y. Chu
1963 The chromosomes of
Primates. In: Evolutionary and Genetic Biology
of Primates. J. Buettner-Janusch, Ed. Academic
Press, New York.
Chu, E. H. Y., and M. A. Bender 1961 Chromosome cytology and evolution i n primates. Science, 133: 1399-1405.
Chu, E. H. Y., and B. A. Swomley 1961 Chromosomes of lemurine lemurs. Science, 133:
1925-1926.
Egozcue, J., and M. Vilarasau de Egozcue 1966
Simplified culture and chromosome preparations of primate lcukocytes. Stain Technol., 41:
173-1 77.
Hagemenas, F., and J. Egozcue ( I n preparation)
Simplified tissue culture and chromosome preparations in primates.
Melnick, J. L. 1956 In: Diagnostic Procedure
f o r Viral and Rickettsial Diseases. 2nd Ed.
American Public Health Association, New York.
Montagna, W., and J. S. Yun 1962 The skin of
Primates. X. The skin of the Ring-tailed Lemur.
Am. J. Phys. Anthrop., 20: 95-118.
Документ
Категория
Без категории
Просмотров
1
Размер файла
842 Кб
Теги
lemuridae, chromosome, variability
1/--страниц
Пожаловаться на содержимое документа