Karyotypes of Pneumocystis carinii from Korean rats.

Molecular karyotyping was applied to Pneumocystis carinii(Pc) from two strains of experimental rats, Sprague Dawley(SD) and Fisher(F), in Korea. Field inversion gel electrophoresis and contour clamped homogeneous electric field electrophoresis resolved 15 chromosomal bands from the Pc. The size of the bands was estimated 270kb to 684kb from SD rats, and 273kb to 713 kb from F rats. The bands of 283 kb from SD rats and of 273 kb from F rats stained more brightly suggesting duplicated bands. Total number of chromosomes was at least 16, and total genomic size was estimated 7 x 10(6) bp. All of the bands from F rats hybridized to the probe of repeated DNA sequences of Pc and the band of 448 kb size was proved to contain rDNA sequences, but Pc. chromosome bands from SD rats showed no reactions to the probes. The 2 different karyotypes of P. carinii from 2 strains of rats were maintained consistently for 2 years.     

Susceptibility of various animals to Pneumocystis carinii infection.

Pneumocystis carinii (Pc) is an important opportunistic pathogen of immune compromised hosts, and is known to infect various animals. The present study observed the infection status of 6 mammals and 3 strains of albino rats with Pc after suppression of their immunity. Methyl-prednisolone was injected once a week and tetracycline was supplied with water for 5 to 21 weeks. Hamsters, guinea pigs, rabbits, dogs, cats and pigs were negative by impression smear, and only the rats were found infected by Pc. All of the three strains of rats, Sprague-Dawley(SD), Wistar(W) and Fisher(F), were infected by Pc but W rats showed heavier degree of infection in earlier period than F or SD rats. The present findings suggest that W rat is the best among the animals used in the present study for production of Pc.     

Observation on the air-borne bacteria and ammonia (NS3) gas in laboratory animal facility with rotary heat exchanger]

The number of air-borne bacteria in air ducts and barrierred laboratory animal rooms with the so-called econovent rotary heat exchanger, were checked monthly during a year by the pin-hole sumpler method for air ducts and Koch method for animal rooms. Also, concentration of ammonia was checked with the same samples by gas impinger. No significantly difference in number of air-borne bacteria was seen between before and after passing the econovent. Those passing through HEPA filter was not detected. There were more air-borne bacteria in animal rooms, outside locker room and shower room than in the corridor, utensil storage, inside locker room and pass box. No ammonia were detected in the outdoor, but exhaust air duct after passing the econovent contained very small amount of ammonia. On the other hand, high concentration of ammonia were preserved in the supplying air duct, exhaust air duct and mice and rats rooms, about 86% of ammonia in exhaust air duct returned back into the supplying air duct. No influences on reproduction in mice and rats were recognized.     

Comparison of pulsed field gel electrophoresis karyotypes of Pneumocystis carinii derived from rat lung, cell culture, and ferret lung

Pulsed field gel electrophoretic karyotypes of Pneumocystis carinii derived from three sources were compared: immunosuppressed virus-free rats transtracheally inoculated with Pneumocystis-infected rat lung; WI-38 cell/Cytodex bead cell cultures inoculated with the same material; and immunosuppressed ferrets which reactivated latent Pneumocystis pneumonia. Karyotypes of DNA from Pneumocystis trophozoites or cysts from rat lung, and trophozoites from cell culture were identical. In contrast, ferret Pneumocystis DNA karyotypes were distinctly different. Rat Pneumocystis gene probes reacted with Southern- transferred rat Pneumocystis DNA but not with ferret Pneumocystis DNA. We concluded that neither the source nor life stage of rat Pneumocystis carinii influenced genomic karyotype, and that rat and ferret Pneumocystis are genetically diverse.     

Inapparent Streptococcus pneumoniae type 35 infections in commercial rats and mice

Streptococcus pneumoniae was isolated from specific-pathogen-free rodents in two rooms at a commercial breeding facility during vendor surveillance testing. In a survey of 274 animals from the two rooms over a period of 7 months, capsular serotype 35 S. pneumoniae was isolated from the upper respiratory tracts of 11% (9 of 82) of C57BL/6 mice in room A and 14% (10 of 72) of F344 rats in room B, but not from WKY rats, BALB/c mice or DBA/2 mice from room A. In both C57BL/6 mice and F344 rats, older rodents had higher colonization frequencies. Nasal lavage cultures gave the best results in identifying colonized rodents. No clinical illness or microscopic lesions were associated with pneumococcal colonization in rats or mice, and no other evidence of potential pathogen infection was found except for positive serologic tests for mouse rotavirus in mice. This is the first report of natural pneumococcal infection in mice, and the first report of type 35 S. pneumoniae infection in rodents. The findings support an earlier observation that pneumococcal infections in rat colonies tend to be monotypic and suggest that the same may be true in mice.     

Variation in the Form of Pavlovian Conditioned Approach Behavior among Outbred Male Sprague-Dawley Rats from Different Vendors and Colonies: Sign-Tracking vs. Goal-Tracking

Even when trained under exactly the same conditions outbred male Sprague-Dawley (SD) rats vary in the form of the Pavlovian conditioned approach response (CR) they acquire. The form of the CR (i.e. sign-tracking vs. goal-tracking) predicts to what degree individuals attribute incentive salience to cues associated with food or drugs. However, we have noticed variation in the incidence of these two phenotypes in rats obtained from different vendors. In this study, we quantified sign- and goal-tracking behavior in a reasonably large sample of SD rats obtained from two vendors (Harlan or Charles River), as well as from individual colonies operated by both vendors. Our sample of rats acquired from Harlan had, on average, more sign-trackers than goal-trackers, and vice versa for our sample of rats acquired from Charles River. Furthermore, there were significant differences among colonies of the same vendor. Although it is impossible to rule out environmental variables, SD rats at different vendors and barriers may have reduced phenotypic heterogeneity as a result of genetic variables, such as random genetic drift or population bottlenecks. Consistent with this hypothesis, we identified marked population structure among colonies from Harlan. Therefore, despite sharing the same name, investigators should be aware that important genetic and phenotypic differences exist among SD rats from different vendors or even from different colonies of the same vendor. If used judiciously this can be an asset to experimental design, but it can also be a pitfall for those unaware of the issue.     

Standard Giemsa C-banded karyotype of Russian wildrye (Psathyrostachys juncea) and its use in identification of a deletion-translocation heterozygote.

Ten accessions of Russian wildrye, Psathyrostachys juncea (Fisch.) Nevski (2n = 2x = 14; NsNs), collected from different geographical regions were analyzed using the C-banding technique. C-banding pattern polymorphisms were observed at all levels, i.e., within homologous chromosome pairs of the same plant, among different individuals within accessions, between different accessions of the same geographic area, and among accessions of different origins. The seven homologous groups varied in the level of C-banding pattern polymorphism; chromosomes A, B, E, and F were more variable than chromosomes C, D, and G. The polymorphisms did not hamper chromosome identification in Ps. juncea, because each chromosome pair of the Ns genome had a different basic C-banding pattern and karyotypic character. A standard C-banded karyotype of Ps. juncea is proposed based on the overall karyotypes and C-bands in the 10 accessions. The C-bands on the Ns-genome chromosomes were designated according to the rules of nomenclature used in wheat. A deletion-translocation heterozygote of Russian wildrye was identified based on the karyotype and C-banding patterns established. The chromosome F pair consisted of a chromosome having the distal segment in the long arm deleted and a translocated chromosome having the distal segment of long arm replaced by the distal segment of the long arm of chromosome E. The chromosome E pair had a normal chromosome E and a translocated chromosome having the short arm and the proximal segment of the long arm of chromosome E and the distal segment of the long arm of chromosome F.     

Electrophoretic karyotype polymorphism of sibling species of the Paramecium aurelia complex

Variability of karyotypes is one of the main mechanisms of speciation in organisms. Electrophoretic karyotypes of the macronucleus (MAC) obtained by pulsed-field gel electrophoresis were compared for 86 strains of all 15 sibling species of the Paramecium aurelia complex in order to determine if karyotype differences corresponded to biological species boundaries. Because the electrophoretic karyotype of the MAC reflects indirectly the frequency and distribution of fragmentation sites in the micronuclear (MIC) chromosomes, any change in MAC electrophoretic karyotype may be a marker of certain chromosomal mutations in the MIC. Thirteen main variants of electrophoretic MAC karyotypes were observed in this species complex. Ten of them appeared to correspond to biological species, while the three other variants characterized several species each. Intraspecific polymorphism was observed for several species: in some cases a certain variant of MAC karyotype was specific for all strains from the same part of the world. Distribution of the MAC karyotype variants along molecular phylogenetic trees of the P. aurelia complex shows that isolation of each species or group of species of this complex was accompanied by divergence in the molecular organization of the genome.     

Growth phase-dependent modification of RNA polymerase in Escherichia coli.

Summary The electrophoretic karyotiype of 11 strains of the phytophatogenic fungus Septoria nodorum has been established by pulsed field gel electrophoresis with the CHEF DRII system. Each strain had a similar overall karyotype with 14–19 chromosomes being resolved in the size interval between approximately 0.5 and 3.5 megabase pairs (Mb). However, there were clear differences in karyotype both between and within groups of strains adapted to wheat or to barley. Considerable karyotype variation was apparent even among 6 wheat-adapted strains isolated from the same population. Only 2 strains possessed identical karyotypes; these were isolated from the same leaf and were heterokaryon-compatible and are probably independent isolates of the same clone.     

Genetic association of crown rust resistance gene Pc68, storage protein loci, and resistance gene analogues in oats

Segregating F(3) families, derived from a cross between oat cultivar Swan and the putative single gene line PC68, were used to determine the association of seed storage protein loci and resistance gene analogues (RGAs) with the crown rust resistance gene Pc68. SDS-PAGE analysis detected three avenin loci, AveX, AveY, and AveZ, closely linked to Pc68. Their diagnostic alleles are linked in coupling to Pc68 and were also detected in three additional lines carrying Pc68. Another protein locus was linked in repulsion to Pc68. In complementary studies, three wheat RGA clones (W2, W4, and W10) detected restriction fragment length polymorphisms (RFLPs) between homozygous resistant and homozygous susceptible F(3) DNA bulks. Four oat homologues of W2 were cloned and sequenced. RFLPs detected with two of them were mapped using F(3) and F(4) populations. Clone 18 detected a locus, Orga2, linked in repulsion to Pc68. Clone 22 detected several RFLPs including Orga1 (the closest locus to Pc68) and three RGA loci (Orga22-2, Orga22-3, and Orga22-4) loosely linked to Pc68. The diagnostic RFLPs linked in coupling to Pc68 were detected by clone 22 in three additional oat lines carrying Pc68 and have potential utility in investigating and improving crown rust resistance of oat.     

Karyological analysis of Proechimys cuvieri and Proechimys guyannensis (Rodentia, Echimyidae) from central Amazon

The aim was to characterize the karyotype of rodents of the genus Proechimys from three localities in the central Brazilian Amazon, in the search for new markers that might shed light on our understanding of the taxonomy and evolutionary history of this taxon. Two karyotypes were found, viz., 2n = 28, FN = 46 in individuals from the NRSP (Cuieiras River) and REMAN (Manaus), and 2n = 46, FN = 50 in individuals from the Balbina Hydroelectric Plant. While individuals with the karyotype with 2n = 28 chromosomes were morphologically associated with Proechimys cuvieri, their karyotype shared similarities with those of the same diploid number in two other regions. Although three karyotypes are described for Proechimys cuvieri, no geographic distribution pattern that defined a cline could be identified. Based on the morphological examination of voucher specimens and additional results from molecular analysis, the karyotype with 2n = 46 and FN = 50 could be associated with P. guyannensis.     

荞麦属2个野生荞麦种的染色体核型研究

对荞麦属皱叶野荞麦(Fagopyrum crispatifolium J.L.Liu)及其近缘种细柄野荞麦[F.gracilipes (Hemsl.) Dam.et Diels]的染色体核型进行了分析.结果表明,2个野生荞麦的染色体数目均为2n=4x=32,但二者在随体数目、染色体长度等方面差异明显,染色体核型不同,皱叶野荞麦的核型公式为:30m(4SAT)+2sm,细柄野荞麦的核型公式为:32m,属首次报道.     

大果榕亚组三种榕树传粉榕小蜂核型研究

研究了木瓜榕(Ficus auriculata Loureiro)、苹果榕(F.oligodon Miquel)及未知榕(Ficus sp.)3种榕树传粉榕小蜂的核型。结果表明:3种榕树对应的传粉榕小蜂具有非常相似的核型,染色体数目相同为2n=10,染色体全部为中着丝粒染色体;核型公式2n=2X=10=10M,核型均为Stebbins-1A型。以臂比不对称性系数Dc和相对长度不对称性系数Dt作二维散点图,Ceratosolen emarginatus Mayr(木瓜榕传粉榕小蜂)和C.emarginatus Mayr(苹果榕传粉榕小蜂)具有非常相近的核型不对称系数,核型不对称性大于Ceratosolen sp.(未知榕传粉榕小蜂),显示出两者更近的亲缘关系,而Ceratosolen sp.(未知榕)与前两者亲缘关系较远。此外,比较了Ceratosolen属和Blastophaga属在核型方面的差异,认为染色体数目包括染色体形态能够作为准确区分Ceratosolen属和Blastophaga属的依据,并对Ceratosolen属的核型进化进行了初步探讨。     

两种榕属植物的染色体核型分析

采用根尖压片法对菩提树(Ficus religiosa Linn.)和小叶榕(Ficus microcarpa L.f.)进行染色体核型分析.结果显示两种植物的染色体数目均为2n=30,核型类型均为1B,核型公式分别为菩提树2n=2x=30=24m(2SAT)+6sm,小叶榕2n=2x=30=28m(2SAT)+2sm.比较发现,两种植物的核型相似,亲缘关系相近,二者中小叶榕的不对称系数较小(58.16%),为较原始的类型.两者的核型均为首次报道.     

黑腹果蝇种组的核型与进化研究

观察了国内黑腹果蝇种组34种果蝇的有丝分裂中期核型,其中首次描述了一些新核型。系统地分析了黑腹果蝇种组8个种亚组之间的核型进化关系及种间亲缘关系。结果是:elegans种亚组的核型为A型;eugracilis、melanogaster和ficusphila种亚组的核型为C型;takahashii和suzukii种亚组的核型为C型和D型;montium种亚组的核型为B、C、C’、D、D’、和E型;ananassae种亚组的核型为F、G和H型。从核型分化的角度可以将黑腹果蝇种组分为5个谱系:elegans,eugracilis-melanogaster-ficusphila,takkahashii-suzukii,montium,ananassae。这与2004年Yang等的观点基本一致,正好从核型进化的角度验证了Yang通过DNA序列分析所得到的结果。差别只在于elegans种亚组,作者把它单独列为一支,认为是祖先种亚组。通过选取同一种果蝇的几个不同地域单雌系的核型分析,结果表明:同一种果蝇的核型存在地域差异。这种差异可能是由于不同生境造成,也可能是本身进化程度的差异,或是两种因素相互作用的结果。     

Electrophoretic karyotypes of clinically isolated yeasts of Candida albicans and C. glabrata.

One-hundred-and-four isolates of yeast were collected from the vaginas of 97 outpatients. The isolates were identified by their characteristics in a carbohydrate assimilation test, a serological test and from their morphology. Candida albicans and Candida glabrata were the major isolates (75% and 20%, respectively). The karyotypes of the isolates were analysed by pulsed-field gel electrophoresis and almost all the karyotypes were distinguishable from one another when the band mobilities were carefully compared. Characteristics and karyotypes were not directly correlated, but seven C. albicans isolates (from six patients) had a common atypical karyotype and shared the same phenotype. These isolates are inferred to be generated by a wide genomic reorganization and mutation and the phenotypic changes may be advantageous for survival. The karyotypes of the isolates recovered from individual patients after intervals of 1-6 months were all identical except for one or two highly variable bands which were identified with an rDNA probe. This suggests that the variable bands are too variable to be useful for distinguishing strains, but from the patterns of the identical bands (i.e. except for the variable bands) we concluded that strains from individual patients do not change, at least over short periods. This, coupled with the extensive inter-isolate variability in karyotype, will be useful for Candida source determination and epidemiological studies.     

Cytogenetic studies of Hynobiidae (Urodela)XVIII. A ZZ/ZW sex-determining mechanism in a hynobiid salamander species,Hynobius tokyoensis Tago

The karyotype of Hynobius tokyoensis (2n = 56) was analyzed using three kinds of banding methods to determine the morphological differentiation of the sex chromosomes of this species. Salamanders and egg sacs were collected from seven localities around Tokyo, Japan. Of 28 chromosome pairs, microchromosome No. 21 was identified as a ZZ/ZW-type sex chromosome. The Z chromosome was acrocentric, whereas the W chromosome was submetacentric, with a heterochromatic, elongated short arm. Interestingly, the W chromosome is of three distinct types, W(A), W(B), and W(C), based on R-banding and Ag-NOR patterns. W(A) was detected in five populations from southern habitats, whereas W(B) and W(C) were detected in one population each from northern habitats. W(A), W(B), and W(C) were all found to carry Ag-NORs on their heterochromatic short arms. Considering the karyotypes of other species belonging to the same genus, we discuss the evolution of the sex chromosomes of H. tokyoensis.     

Die überwinterung als adaptive leistung,Geprüft an verschiedenen karyotypen der inversionspolymorphen art Drosophila subobscura

Adult flies of Drosophila subobscura were kept in a refrigerator for 72 days. The animals belonged to a second generation derived from a cross between two homokaryotypic stocks. One of these was homozygous for the Standard (St) gene arrangement of the U-chromosome, the other one for the gene arrangement U₁₊₂, which differs from the U_St by two inversions. Both gene arrangements are abundant in natural populations of Northern and Central Europe.According to Mendelian expectations the karyotypes U_St/St, U_St/1+2 and U_1+2/1+2 should show up in the second generation in conformity with the proportion 1 : 2 : 1. A random sample of 70 adults taken before confining the animals to the refrigerator contained 11 : 43 : 16 specimens of the above mentioned karyotypes respectively. Karoytypic proportions observed after keeping the flies in the cold were therefore compared not only with the hypothetical 1 : 2 : 1 proportion but also with the 11 : 43 : 16 proportion of that prior sample. There was however no significant deviation from the latter proportion. For both males and females the result remained the same, independent of whether or not they had copulated. Animals which had been kept and normally fed for the same duration at 18°C showed no significant deviation from the initial karyotype proportion, either. Thus the attempt to show through karyotype proportions an adaptation to long periods of cold was entirely unsuccessful.In a second run I buried eggs, the three larval stages, and pupae as well as adults into the forest soil in autumn for exposure to the winter cold. A sample was removed 125 days later, the remaining 180 days after having been dug in. As in the first run the flies showed no significant changes in karyotype proportions. While death rate seemed to be homogeneous, the three karyotypes nevertheless showed some differences in viability.In laboratory tests, those male and female specimens which had not copulated withstood the cold better. The highest mortality rate occurred among sexually mixed groups. Further, a shorter life span and lower fertility rate were found in animals kept at 18°C than in those kept in the refrigerator.Among the animals that had been dug into the forest soil only those survived, which had started the cold period as immature stages. They developed very slowly. These ecological findings suggest that Drosophila subobscura hibernates in its immature stages rather than as adult flies.Very young larvae were found to have the best chance of survival. This observation led to a third experiment: I exposed young larvae to a cold shock treatment. Thereby a first hint was obtained concerning the presumed differences in adaptive capacities of different karyotypes. After a cold shock the development of the homokaryotypes, from the egg to the larval stage, was faster and in one case there even emerged more homokaryotype than heterokaryotype larvae.     

The Effects of Shipping on Early Pregnancy in Laboratory Rats

Although rats in various stages of pregnancy are routinely shipped by vendors, the effects of shipping on pregnancy outcomes have not been reported. This study examined the effects of shipping rats 1 day after mating. Two outbred stocks, (Crl:CD(SD), Crl:WI(Han)) and one inbred strain (F344/Crl) of rats (n = 300/strain) were mated in a vendor barrier room at 3‐month intervals five times, and either shipped the next day (total time in transit ～24 hr) or held in the room of origin until parturition. The pregnancy status, length of gestation, number of pups born per female, sex ratio of pups born, and neonatal mortality were compared between transported and nontransported rats. These pregnancy and litter parameters were also compared among strains and examined for seasonality; no seasonal effects were observed. Neonatal mortality was negligible at less than 2% in any of the groups. All sex ratios were normal. Transportation affected pregnancy rates only in the F344/Crl, in which 81.8% of the nontransported versus 70% of the transported rats had pups (p = 0.025). Overall, slightly fewer transported rats were pregnant, but they had larger litters (10.08 compared with 9.68, p = 0.02, pooling across all three strains) so produced the same numbers of pups. A total of 77 ± 8% of transported rats had gestation periods of 22 days or more compared with only 52 ± 10% in the nontransported rats. The reason for larger litters in transported females is unclear. Longer gestation in transported females may be due to facultative embryonic diapause, which might have implications for reproductive toxicology.