共查询到18条相似文献,搜索用时 171 毫秒
1.
观察了同翅目头喙亚目12种沫蝉雄性的染色体数目和减数分裂行为。通过对沫蝉总科现有核型资料的分析,认为沫蝉总科的核型特点是:①染色体较小,数目较多,总科内染色体数目变化范围较大,众数为2n=26(24+XO);②染色体的易位现象极为普遍,因此可以推测,通过染色体的易位导致染色体数目增加是核型进化的主要机制;③减数分裂前期Ⅰ具有典型的花束期,但没有弥散期。因此从精子发生来看沫蝉总科与叶蝉总科、角蝉总科和蝉总科的关系更为密切,而与蜡蝉总科的关系较远。头喙亚目的亲缘关系可能是:蜡蝉总科+{蝉总科+[沫蝉总科+(叶蝉总科+角蝉总科)]}。 相似文献
2.
3.
本文记载了中国25种角蝉的染色体,研究表明染色体的数目、大小及其在减数分裂过程中的行为具有种或属一级的分类特征。该科昆虫染色体的数目变异在n=5到12之间,众数为n=11,另外,n=10的类型也较为普遍。绝大多数种类的性别决定机制为XO型,仅个别种类具有新XY性染色体系统。 相似文献
4.
5.
6.
利用整体压片法 ,对分别隶属于球角科和长角科的两种跳虫似微小球角 (Hypogastruraadex ilis (Stach ,196 4 ) )和曲毛裸长 (SinellacurvisetaBrook 1889)的染色体进行了首次观察。发现似微小球角单倍染色体数目n =7,雄性有 13条染色体 ,雌性有 14条 ,为XO型性别决定 ;曲毛裸长n =6 ,雄性 2n =11,雌性 2n =12 ,同样为XO型性别决定。还记述了雄性似微小球角的减数分裂过程 :在分裂前期 ,同源染色体进行配对 ;部分同源染色体发生交叉 ,部分仅末端相连 ;早后期Ⅰ ,当常染色体向两极移动时 ,性染色体仍滞后于赤道板中央。 相似文献
7.
黄芩的花粉母细胞减数分裂及核型分析 总被引:1,自引:0,他引:1
采用压片法,对黄芩花粉母细胞减数分裂及核型进行了研究。结果表明:黄芩的大多数花粉母细胞减数分裂中染色体的行为正常,在终变期同源染色体配对后可形成9个二价体,后期Ⅰ染色体以9∶9的方式向细胞两极分离,其减数分裂为同时型;在少数花粉母细胞减数分裂中观察到落后染色体、染色体桥等异常行为;其花粉粒育性为76.49%。黄芩的染色体数目为2n=2X=18,核型公式为K(2n)=2X=18=16m+2 sm,染色体相对长度组成为2n=1 s+4M1+3M2+1L,其核型为"1A"型。 相似文献
8.
9.
蛾螺科三种螺的核型观察 总被引:5,自引:0,他引:5
本文介绍了蛾螺科三种螺的核型。水泡蛾螺(Buccinum pcmphigum)为2n=30,染色体的形态分类组成为16m+10sm+4st,NF=56;Plicifusus scissuratus为2n=34,染色体的形态分类组成为20m+10sm+4st,NF=64;香螺(Neptumea cumingi)为2n=60,染色体的形态分类组成为30m+22sm+8st,NF=112。 蛾螺科核型分析,显示贝类染色体数目及其形态与贝类进化有关。 相似文献
10.
麦蓝菜的花粉母细胞减数分裂及核型分析 总被引:1,自引:0,他引:1
采用压片法,对麦蓝菜的花粉母细胞减数分裂及体细胞核型进行了研究。结果表明,麦蓝菜的绝大多数花粉母细胞减数分裂中染色体的行为正常,在终变期同源染色体配对后可形成15个二价体;在少数花粉母细胞减数分裂中观察到落后染色体、染色体桥等异常行为;其减数分裂为同时型,其花粉粒育性为88.04%。麦蓝菜的染色体数目为2n=2X=30,核型公式为K(2n)=2X=30=22m(2SAT)+8 sm,染色体相对长度组成为2n=16M2+14M1,其核型为"1A"型。 相似文献
11.
R J O'Neill M D Eldridge R Toder M A Ferguson-Smith P C O'Brien J A Graves 《Génome》1999,42(3):525-530
Marsupial mammals show extraordinary karyotype stability, with 2n = 14 considered ancestral. However, macropodid marsupials (kangaroos and wallabies) exhibit a considerable variety of karyotypes, with a hypothesised ancestral karyotype of 2n = 22. Speciation and karyotypic diversity in rock wallabies (Petrogale) is exceptional. We used cross species chromosome painting to examine the chromosome evolution between the tammar wallaby (2n = 16) and three 2n = 22 rock wallaby species groups with the putative ancestral karyotype. Hybridization of chromosome paints prepared from flow sorted chromosomes of the tammar wallaby to Petrogale spp., showed that this ancestral karyotype is largely conserved among 2n = 22 rock wallaby species, and confirmed the identity of ancestral chromosomes which fused to produce the bi-armed chromosomes of the 2n = 16 tammar wallaby. These results illustrate the fission-fusion process of karyotype evolution characteristic of the kangaroo group. 相似文献
12.
同翅类昆虫的雄性生殖系统及精子发生(昆虫纲:半翅目) 总被引:3,自引:1,他引:2
本文比较了同翅类昆虫雄性生殖系统的结构、减数分裂期间染色体的行为和精子尾部的超微结构。研究表明蜡蝉总科和异翅类的精巢具有被膜,而蝉总科、叶蝉总科、沫蝉总科、角蝉总科、木虱总科、蚜总科、粉虱总科和蚧总科的精巢均不具有被膜。也可以根据精巢小叶的形状将精巢分为三类,蝉总科、叶蝉总科、沫蝉总科、角蝉总科、蚜总科和粉虱总科的精巢小叶为球形,蜡蝉总科、木虱总科和蚧总科的精巢小叶为管状,而异翅类的精巢小叶为片层状。减数分裂可以被分为5类:①蝉型(Cicadoidtype);②蜡蝉型(Fulgoroidtype);③木虱型(Psyloidtype);④蚜型(Aphidoidtype);⑤粉虱型(Aleyrodoidtype)和⑥蚧型(Coccoidtype),至少具有四个类群的减数分裂前期I具有弥散期,它们是:木虱总科、蜡蝉总科、蚧总科和异翅类。除粉虱总科和蚧总科的精子尾部退化以外,其余种类的精子鞭毛均具有典型的9 9 2轴丝结构。 相似文献
13.
Abstract Chromosomes in 25 species of Membracidae are recorded. Numbers, size and behaviors of the chromosomes during meiosis and mitosis are used as specific or generic features for the taxonomy of this group. Chromosome numbers vary from n=5 to 12, and sex mechanism are of XO type except two species with neo-XY system. The histogram indicates that 2n=11 with XO sex mechanism is the modal chromosome number, and another type n=10 is also commonly found in this family. 相似文献
14.
Rens W O'Brien PC Fairclough H Harman L Graves JA Ferguson-Smith MA 《Cytogenetic and genome research》2003,102(1-4):282-290
The karyotypes of marsupial species are characterized by their relatively low number of chromosomes, and their conservation. Most species have diploid numbers lying between the two modes, 2n = 14 and 2n = 22, but the karyotype of Aepyprymnus rufescens is exceptional in containing 2n = 32 chromosomes. Many differences in diploid number between marsupial species can be accounted for by particular fissions and fusions, which are easy to detect because of the low numbers of chromosomes in each karyotype. This should be a system in which it is possible to detect reversals and repeated chromosome rearrangements. We have used chromosome-specific paints derived from A. RUFESCENS to compare the karyotypes of eight marsupial species, representing closely and distantly related taxa, to trace chromosome change during evolution, and especially to detect reversals and convergence. From these and other painting comparisons, we conclude that there have been at least three reversals of fusions by fissions, and at least three fusions or fissions that have occurred independently in different lineages. 相似文献
15.
The genus Lycoris (Amaryllidaceae) consists of about 20 species, all of which are
confined to temperate China, Japan and Korea.
Cytological investigations, including a reexamination of the karyotypes of 14 taxa, measurements of relative nuclear DNA content, and meiotic configuration observations on some specific
forms and interspecific hybrids, have been carried out by the present authors in order to re-evaluate the mode of karyotype evolution and the role of hybridization in the speciation of Lycoris.
These have resulted in a new theory for explaining the karyotype evolution in the genus, which
will be considered elsewhere. The present paper deals with observations on karyotypes of 11
species, 1 variety and 2 artificial hybrids.
Results obtained through karyotype analysis, as shown by the data in Table 1, Plates I-VI
and Figs. 1-2, reveal that: (1) the karyotypes of Lycoris rosea, L. radiata var. pumila, L. sprengeri, L. haywardii, L. caldwellii, L. squamigera and L. radiata are, on the whole, consistent with
those reported by the previous authors[1,2,3,4,5,8,10,12];(2) the I (rodshaped) chromosomes of L.
chinensis and L. longituba are all T’s (telocentric) instead of t’s (acrocentric) or t(Sat)’s;
(3) the three materials of L. aurea of different sources have shown a karyotypic differentiation:
one with 2n=14=8m+6T, and the others with 2n=16=6m+10T: (4) both of the karyotypes
of L. straminea and L. albiflora are 2n=19=3V+6I, inconsistent with 2n=16=6V+10I for the
former and with 2n=17=5V+12I for the latter as reported by Inariyama (1953), Bose and
Flory (1963) and Kurita (1987).
The following aspects are worthwhile discussing:
1. The types of chromosomes.
Karyotype analyses reveal the existence of three major chromosome types in Lycoris: (1)
m (metacentric) chromosomes: (2) t (acrocentric) chromosomes, with short arms, (3) T (telocentric) chromosomes, sometimes with dot-like terminal centromeres. To distinghish t’s from
T’s is of paramount importance for solving the problem of karyotype evolution in Lycoris.
Bose (1963) pointed out that in the species with 2n=22, all I chromosomes were t’s, while in
species with 2n=12-16, all I chromosomes were T’s. Our results of chromosome observations
are consistent with Bose’s remarks. Some authorst[3,6] have probably mistaken the dot-like terminal centromeres of T’s of L. longituba and L. chinensis as the short arms of t’s.
2. The significance of Robertsonian change in karyotype evolution.
Although chromosome numbers and karyotypes are very variable in Lycoris, as shown in
Table 1, the total number of arms of a chromosome complement of any species is always multiples of 11. Hence, it seems likely that Robertsonian changes have taken part in karyotype
alteration, The genus has a series of basic chromosome numbers: 6, 7, 8 and 11. But which is
the most primitive one? It is uncertain whether a successive decrease in chromosome numbers
as a result of Robertsonian fusion or a gradual increase in chromosome numbers brought about
by fission (fragmentation) has been the essential mechanism for karyotype evolution and speciation in Lycoris. These problems are of crucial importance and will be discussed in our
subsequent papers.
3. The origin of polyploids.
As evident from Table 1, there are two levels of ploidy differentiation in Lycoris: (1) di ploids with 2n=22 or the equivalent of 22, (2) triploids with 2n=33 or the equivalent of 33.
The most common way of origination of triploids in plants is the hybridization of diploids with
Tetraploids. But tetraploids have never been found in Lycoris. Thus, it is suggested that the
triploids have originated from the combination of an unreduced gamete of a diploid with a
normal gamete of another diploid.
4. The role of hybridization in speciation.
Results of karyotype analyses show that hybridization has taken an important part in the
speciation of Lycoris. Two types of hybrids have been found: (1) 2n=19= 3V+ 16I, L. straminea, L. albiflora and the two artificial hybrids L. sprengeri×L. chinensis and L. haywardii×
L. chinensis all possess this karyotype. It could be seen from the above chromosome number and
karyotype that this sort of karyotype is exactly half of the total sum of 2n=22I and 2n=16=
6V+10I. It is, therefore, quite evident that taxa possessing this karyotype are all diploid
hybrids of 2n=22 and 2n=16, (2) 2n=27=6V+21I, L. caldwellii and L. squamigera possess
this karyotype. It is reasonable to assume, too, that they are segmental allotriploids and have
arisen from the combination of an unreduced diploid gamete of 2n=16 and a normal haploid
gamete of 2n=22. The origin of the hybrid karyotype 2n=17=5V+12I reported by Inari-
yama (1953) is similar to that of 2n=19, except that one of the parents possesses 2n=12=
10V+2I instead of 2n=16=6V+10I. The origin of the other hybrid karyotype 2n=30=3V+
27I reported by Bose (1963) is similar to that of 2n=27, but the diploid gamete comes from
taxa possessing 2n=22 instead of 2n=16. 相似文献
16.
青海四种雏蝗染色体核型的比较分析 总被引:1,自引:0,他引:1
采用常规染色体制片方法对雏蝗属的褐色雏蝗Chorthippusbrunneus(Thunb .) ,异色雏蝗C .big uttulus(Linnaeus) ,小翅雏蝗C .fallax(Zub .) ,青藏雏蝗C .qingzangensis(Ying)的染色体核型进行分析 ,结果 :染色体数目均为 2n(♂ ) =1 7=1 6+XO ;常染色体类型为两类 ,中着丝点染色体 (m ,6条 )和端着丝点染色体 (T ,1 0条 ) ;性染色体类型为端着丝点。褐色雏蝗、异色雏蝗和青藏雏蝗的核型公式和染色体的相对长度组成为K( 2n ,♂ ) =1 7=6m +1 1T =6L +6M +4S +XO ,K( 2n ,♀ ) =1 8=6m +1 2T =6L +6M +4S +XX ;小翅雏蝗的为K( 2n,♂ ) =1 7=6m +1 1T =6L +4M +6S +XO ,K( 2n ,♀ ) =1 8=6m +1 2T =6L +4M +6S+XX。褐色雏蝗性染色体中部有次缢痕。染色体臂数 4种均为NF =2 3(♂ ) ,2 4 (♀ )。 相似文献
17.
18.
de Bigliardo GR Gabriel Virla E Caro S Murillo Dasso S 《Revista de biología tropical》2011,59(1):309-314
Cicadellidae in one of the best represented families in the Neotropical Region, and the tribe Proconiini comprises most of the xylem-feeding insects, including the majority of the known vectors of xylem-born phytopathogenic organisms. The cytogenetics of the Proconiini remains largely unexplored. We studied males of Tapajosa rubromarginata (Signoret) collected at El Manantial (Tucumán, Argentina) on native spontaneous vegetation where Sorghum halepense predominates. Conventional cytogenetic techniques were used in order to describe the karyotype and male meiosis of this sharpshooter. T. rubromarginata has a male karyological formula of 2n = 21 and a sex chromosome system XO:XX (male:female). The chromosomes do not have a primary constriction, being holokinetic and the meiosis is pre-reductional, showing similar behavior both for autosomes and sex chromosomes during anaphase I. For this stage, chromosomes are parallel to the acromatic spindle with kinetic activities in the telomeres. They segregate reductionally in the anaphase I, and towards the equator during the second division of the meiosis. This is the first contribution to cytogenetic aspects on proconines sharpshooters, particularly on this economic relevant Auchenorrhyncha species. 相似文献