The quantity of associated acrocentric chromosomes in human lymphocytes passing through 1st, 2d and 3d mitoses in culture

The reproductive ability of lymphocytes of peripheral blood with the usage of 5-bromine-deoxyuridine has been studied in 8 healthy children at the age of 5-6 years. Single second mitoses occurred in 48 hour cultures (6.5%), in 72 hour cultures the frequency of the first, second and third mitoses was equal, in 96 hour cultures the third mitoses dominated. Consequent divisions of lymphocytes were accompanied by a decrease in associative acrocentric chromosome, in average by 25%, within one mitotic cycle, while in mitoses of a given ordinal number the frequency of associations did not depend on the duration of cultivation. The fixation of the culture at the 48th hour of cultivation makes it possible to take into account the frequency of associations of acrocentric chromosomes without calculation of the ordinal number of mitosis because of an significant amount of second mitoses at this time, and of a sufficient value of the mitotic index (4.6 +/- 0.5%) necessary for cytogenetic analysis.     

Differences in fertility and suckling patterns between primiparous and multiparous rhesus mothers (Macaca mulatta)

Primiparous females gave birth around the same time as multiparous nonlactating females, and earlier than did multiparous lactating females. No differences in birth sex ratio were found between primiparous and multiparous females. During the breeding season following birth, primiparous mothers returned to oestrus later than did multiparous mothers, and while few primiparous mothers conceived successfully during that season, most multiparous mothers did. Primiparous females suckled their infants more frequently than did multiparous females at all ages; infants of primiparous females also made more nipple contacts per bout, and had shorter sucking bouts. When mothers came into oestrus, suckling frequency drastically increased for primiparous females, but not for multiparous females, magnifying the differences between the two groups. After the first oestrus, suckling frequency declined for all mothers, but multiparous mothers had consistently lower suckling frequencies than did primiparous mothers. The high suckling frequency, and numerous nipple contacts per bout, found among primiparous mothers are likely to be related to the low reproductive chances that these females faced during the breeding season. Multiparous mothers seemed to compensate for their low suckling frequency by lengthening the suckling bouts, and this suckling pattern did not hinder their reproduction. It is argued that primiparous mothers might have to suckle their infants more frequently because they can only produce milk at slow rates, being in this way forced into a reproductively inhibiting suckling pattern. However, the delay in subsequent reproduction could be ultimately advantageous for primiparous mothers if it enhanced infant survival, and allowed the mothers to regain physical condition before reproducing again.     

A comparison of primiparous and multiparous mother-infant dyads inMacaca mulatta

The relationships of 42 rhesus monkey mother-infant dyads were examined to investigate the effects of the mothers' parity. Primiparous mothers were found to be younger, more excitable and less confident than the multiparous mothers. They also received more aggression from other adult females living in their social group and were more anxious about their infants, approaching and leaving them more frequently. The primiparous mothers protected their daughters more than the multiparous mothers and their daughters correspondingly spent more time in the ventro-ventral position and more time on the nipple. Their sons however spent less time in contact with their mothers than did the sons of the multiparous mothers. Although the primiparous mothers protected their daughters more than their sons, for the multiparous mothers the converse was true and sons received more maternal protection. It is suggested that the greater protectiveness of the multiparous mothers towards male infants may be a consequence of the interest siblings have in males, whereas the greater protectiveness of primiparous mothers to daughters may stem from their greater vulnerability to attacks from adult females. The importance of mother-mediated sibling influences may explain the lack of strong parity differences in previous studies.     

Variability in the development of mother-infant relationships among free-ranging Japanese macaques

Mother-infant relationships were studied during the infant's first year in free-ranging Japanese macaques (Macaca fuscata). Three possible factors controlling the mother-infant relationships were examined using multivariate analysis. Parity was determined to exert the strongest influence on mother-infant relationships. Specifically, during month 1, multiparous mothers showed greater maternal suckling rejection than primiparous mothers, and primparae and multiparae differed in their responses to suckling behavior. During month 6, multiparous mothers prompted independence of their offspring more than primiparous mothers. By month 8, however, parity differences in maternal behavior were substantially reduced. Maternal rank was a less important factor, although during month 1, high-ranking mothers showed greater maternal restriction than low-ranking ones. In the present study, infant gender appeared to have no effect on mother-infant relationships. That most differences were due to parity indicates that mother-infant relations were largely determined by the mothers. This observation conflicts with the “learning-to-mother” hypothesis. Allo-mothering of neonates by nulliparae is rare among Japanese macaques. Primiparous mothers learned appropriate suckling care from handling their own infants.     

Cytogenetic observations on XX/XY chimaeras and a reassessement of the evidence for germ cell chimaerism in heterosexual twin cattle and marmosets.

Testicular preparations were obtained from 7 bulls, twins of freemartins, and 1 male marmoset, all proved XX/XY chimaeras. X and Y sex chromosomes were confidently identified in nearly all the 87 spermatogonia at mitotic metaphase and 1052 primary spermatocytes at diakinesis-metaphase examined: no cell was identified as containing two X chromosomes. The germ cell chimaerism previously reported in these species is therefore not confirmed. Cultures grown from presumptive somatic these species is therefore not confirmed. Cultures grown from presumptive somatic cells in the testes of two of the bulls yielded 248 identifiable mitotic spreads, all XY-type; cultures from the gonads of their freemartin twins yielded 442 mitotic spreads, all XX-type. Direct preparations from one freemartin gonad, however, yielded 3 XY mitotic spreads out of 18 examined. The conflicting evidence concerning germ cell chimaerism in cattle and marmosets is discussed, particularly in relation to reports of XX/XY bulls that have sired a great excess of daughters. The possibility that XX germ cells contributed to the functional spermatozoa of these bulls is not favoured by present information, but is not excluded.     

Chromosomal aberrations in patients with primary biliary cirrhosis

Summary Chromosomal aberrations in untreated lymphocyte cultures, bleomycin (BLM)-induced aberrations and sister chromatid exchanges (SCE) in the peripheral blood lymphocytes of 11 patients suffering from primary biliary cirrhosis (PBC) and 14 matched control individuals were analysed. The lymphocytes of the PBC patients had on average a lower mitotic index (2.3) compared with controls (3.5) in the untreated cultures. The mean baseline rate of aberrations of the cultured lymphocytes of the patients was 5.3 aberrations per 100 metaphases (%); this was significantly different (P=0.0291) from that of the controls with a mean of 2.3%. In lymphocytes of the patients and controls, most of the aberrations observed took the form of gaps; there was an almost equal breakage rate in both groups (0.5% and 0.4%, respectively). The average number of mitoses with aberrations in the PBC patients studied was double that of the controls (4.9% and 2.3% respectively, P=0.0323). The mean number of the BLM-induced aberrations was 54.0% and 27.7% for the lymphocytes of the patients and controls, respectively. The mean number of the aberrant mitoses in the BLM cultures was 6 times higher than that of the untreated cultures for both groups, 25.7% and 14.6% respectively (P=0.018). The chromosomal distribution of baseline and induced aberrations was not random. The PBC patients had a mean number of 8.7 SCE per mitosis, which was significantly higher than the SCEs in the controls (6.3 SCE per mitosis; P=0.0156). The evidence suggests that the chromosomes of the lymphocytes of PBC patients may be less stable than those of the control individuals in this study.     

Reproductive parameters of female Japanese macaques: Thirty years data from the arashiyama troops,Japan

Over a 30-year period from 1954 to 1983, 975 live births were recorded for Japanese macaque females at the Iwatayama Monkey Park, Arashiyama, Japan. Excluding unknown birth dates, primiparous mothers gave birth to 185 infants (182 cases with age of mother known) and multiparous mothers gave birth to 723 infants (603 cases with age of mother known). The peak month of birth was May with 52.3% of the total births occurring during the period. Multiparous females who had not given birth the previous year did so earlier than multiparous females who had given birth the previous year and also earlier than primiparous females. Among the females who had given birth the previous year, females whose infant had died gave birth earlier than females who had reared an infant the previous year. The offspring sex ratio (1:0.97) was not significantly different from 1:1, and revealed no consistent association with mother's age. Age-fecundity exhibited a humped curve. The annual birth rate was low at the age of 4 years but increased thereafter, ranging between 46.7% and 69.0%, at between 5 and 19 years of age, but again decreased for females between 20 and 25 years of age. Some old females displayed clear reproductive senescence. The infant mortality within the first year of age was quite low (10.3%) and the neonatal (less than 1 month old) mortality rate accounted for 49.0% of all infant deaths. There was no significant difference between the mortality rates of male and female infants. A female's rank-class had no apparent effect on the annual birth rate, infant mortality, and offspring sex ratio. These long-term data are compared with those from other primate populations.     

Immunophenotype and sister chromatid differentiation: a combined methodology for analyzing cell proliferation in unfractionated lymphocyte cultures

Combination of the MAC (morphology, antibody, chromosomes) and harlequin staining procedures offers a method for direct analysis of cell kinetics in cultures of unfractionated hematopoietic cells. In the present study unfractionated human mononuclear leukocyte cultures were stimulated with PHA or PWM mitogens and exposed to bromodeoxyuridine for various periods. For MAC, cytospin preparations were made and cells were classified with monoclonal B and T antibodies by the immunoperoxidase technique. After differentiation of the different lymphocyte subsets, the cells were stained by a fluorescence-plus-Giemsa method to distinguish sister chromatids and to determine the proportions of first, second, third, or subsequent mitoses among the previously identified subsets. The results showed (1) that the relative proportions of mitotic T and B cells are the same regardless of the mitogen used; (2) that T and B lymphocytes proliferate faster in cultures stimulated by PWM than in those stimulated by PHA; and (3) that T cells enter mitosis earlier than B cells when PHA or PWM are used as mitogens.     

Leydig cell mitoses in human testes bearing early germ cell tumors

Summary Numerous mitoses were noted in testicular tissue from adult men with early germ cell tumors. More than 15 Leydig cells undergoing mitosis were found in the interstitial compartment. The presence of specific crystalline intracytoplasmatic inclusions demonstrated for the first time that differentiated Leydig cells are capable of proliferation. Occasionally cells are difficult to discriminate during mitosis. To establish reference criteria, the light- and electron-microscopic features of the following mitotic cells were examined: Leydig cells, fibroblasts, perivascular cells, peritubular cells, and lymphocytes. Supplementary mitoses in germ cell tumors and in a case of Leydig cell tumor were investigated. In the literature, only single reports of mitoses in Leydig cells are available. The frequent incidence of Leydig cell mitosis in early germ cell tumors may be due to the presence of growth-promoting factors in the testicular tissue.     

Bleomycin-induced chromosomal aberrations in Down's syndrome lymphocytes

Blood samples from 4 Down's syndrome (DS) patients with a 47,XY,21 + karyotype and from 4 normal male probands were cultured for 72 h in the presence of BrdU and lymphocytes analysed at their first mitosis for chromosomal aberrations. The frequencies of spontaneous aberrations and the proportions of cells in the first or later mitoses in culture were not different between the groups. Treatment with various doses of bleomycin in vitro resulted in similar delays in cell development for both DS and normal lymphocytes and dose-dependent increases in the incidence of chromosome-type aberrations. However, the induction of both dicentric aberrations and acentric fragments was significantly enhanced in DS cells relative to cells of normal karyotype.     

Neonatal abandonment in Japanese macaques

This study analyzed long-term demographic data relative to a captive colony of Japanese macaques (Macaca fuscata) in order to evaluate factors predicting increased probability of infant neonatal abandonment. Overall, 7.7% of liveborn infants were abandoned at birth. Probability of abandonment was significantly increased in primiparous and, to a lesser extent, low-ranking mothers. Primiparous mothers abandoned about 40% of their infants at birth. Mother age and infant sex had no independent effects on the probability of neonatal abandonment. Primiparous mothers that did not abandon their infants suffered increased infant mortality and showed longer interbirth intervals compared to same-age multiparous mothers. These results are partially consistent with adaptive hypotheses predicting maternal divestment under unfavorable conditions, and with proximate explanations linking abandonment to inexperience and stress.     

Role of multipolar mitoses in the proliferation of multinucleate cells induced by cytochalasin B

A prolonged action of cytochalasin B results in the formation of numerous multipolar mitoses (26%) in Chinese hamster cell cultures. The transition to multipolar mitoses in the presence of cytochalasin B is not accompanied by K-mitotic delay. It is shown that a multipolar mitosis without cytoplasmic division is one of the main causes of multinucleation development in cytochalasin B-treated cultures. After stopping the drug action the cytochalasin B-induced multinucleate cells continue to divide by multipolar mitosis. In this case it completes with cytokinesis and, probably, leads to a decrease in the number of nuclei per cell. The origin of multipolar mitotic apparatus after the action of cytochalasin B is discussed in addition to the role of multipolar mitosis in formation and proliferation of multinucleate cells.     

Marker Chromosome Analysis of Tetraparental AKR↔CBA-T6 Mouse Chimaeras

Marker chromosome analysis of 18 tetraparental AKR↔CBA/H-T6 chimaeras revealed a great excess of AKR mitoses over CBA mitoses in direct preparations from lymphomyeloid tissues, corneal epithelium, intestinal epithelium and skin (Table 1). The degree of AKR dominance was strongly influenced by anatomical site (Tables 2 and 3). The testes of three out of four XY/XY males contained a marked excess of AKR germ cells and produced a parallel excess of functional AKR gametes (Table 4). Mitotic spreads in mitogen-stimulated cultures of tail blood were overwhelmingly of AKR type in 1972, but less so in 1973 (Table 5).
The coat phenotypes, and breeding results from known or presumptive XX/XX females, suggest that AKR and CBA cells were numerically balanced when melanoblasts and oocytes were formed during embryonic development, and therefore that the striking deviations from equality observed in mitotic populations of adult chimaeras arose later by differential proliferation or survival of AKR cells, or both.
The low frequency of lymphomas, compared with normal AKR mice, previously reported in these chimaeras cannot therefore be accounted for by insufficiency of AKR cells in the thymus or elsewhere in the lymphomyeloid tissues. One of three lymphomas studied was CBA type. This suggests that the high risk of lymphomatous transformation is not an autonomous property of AKR cells.     

Evidence for Sex-Biased Behavioral Maternal Investment in the Gray Mouse Lemur (Microcebus murinus)

To study sex-differential allocation of maternal behavior in Microcebus murinus, I recorded behavioral patterns on 21 litters from parturition to the weaning period. After a pregnancy of 61.5 ± 0.9 days, females may produce from one to four young per litter. Litters were weaned in 40 days by mothers. Behavioral observations at the beginning of the nocturnal activity period demonstrated that close contacts between mothers and infants were more frequent in multiparous mothers than in primiparous ones (p < .01). Time in close contact with offspring aged >15 days old compared to contacts with neonates is significantly lower only in single-sex litters and is more marked for all-female litters (p < .01). Mother's approaches toward mixed litters or all-male litters were always significantly greater than approaches toward all-female litters (p = .04). However, mother's approaches within mixed sex litters were not biased toward either sex (p = .7). Males in a litter may be interpreted as a stimulator of maternal behavior. Similarly, using retrieving tests of 15-min duration, a significant maternal preference for male neonates is evident. Latency to first retrieval is significantly shorter in multiparous females than in primiparous ones (p < .05) independent of size and sex ratio of the litter. For multiparous females only, male neonates were chosen first for retrieval more often than females (p < .05). Finally, the calls of young played a stimulator effect on maternal retrieving (p < .001). Accordingly multiparous mothers exhibit more interest in their young, which appears to be biased toward male neonates.     

Fetomaternal transfusion of blood lymphocytes and identification of the sex of the fetus

Karyotypes of blood lymphocytes were studied in 21 pregnant women. In 8 cases, 46,XY cells were found in the maternal blood and a boy was born in all cases. In 3 cases various chromosome rearrangements were seen. In 6 cases, no 46,XY cells were seen and a girl was born in each case. In 3 cases no 46,XY cell was observed (in 800 cells) and boys were born. In 3 other cases, a 46,XY cell was found and girls were born; all mothers had previously given birth to boys. In 1 case, 2 46,XY cells were observed, and a girl was born; the mother had had an induced abortion in the 3rd month of pregnancy 3 years earlier. It was concluded that the detection of a male fetus seems possible in pregnant women who have no previous male progeny. The persistence of cells from previous pregnancies appears to be a possibility, however.     

Occurrence and possible consequences of multipolar mitoses in primary cultures of adult rat hepatocytes

Proliferating primary cultures of adult rat hepatocytes are characterized by the occurrence of multipolar mitoses, and chromosome loss resulting in the formation of micronuclei at telophase. The percentage of multipolar mitotic figures was determined to be 12.76 ± 7.9%, 80% of which were tripolar. Multipolar mitotic stages showed a high incidence of chromosome loss, increasing from meta- (61.7 ± 16.6%) to telophase (72.1 ± 19.3%). Regular bipolar mitotic figures on the other hand also showed chromosome loss, however, to a lesser degree and decreasing from meta- (49.5 ± 10.4%) to telophase (34.9 ± 7.9%). The incidence of chromosome loss even in regular mitotic figures is very high compared to other cells and appears to depend on another special feature of hepatocytes: they remain flat and well attached during mitosis, so that shearing forces could be responsible for the separation of chromosomes from the mitotic spindle. Additionally this morphology creates a situation allowing for a maximal interaction of mitotic spindles of binucleated cells, leading to the high rate of multipolar mitoses observed. Both multipolar mitoses and chromosome loss could also explain the consecutive detachment of hepatocytes reported for proliferating primary cultures, since the aneuploid daughter cells generated can be expected to be nonviable in most cases and eventually detach. © 1993 Wiley-Liss, Inc.     

Infant development in two aquarium bottlenose dolphins

The behavioral development of two aquarium bottlenose dolphin calves, one male (born to a primiparous mother) and one female (born to a multiparous mother), was examined. From birth to 9 weeks of age, a total of 558.7 h of nursing and behavioral data were collected using focal sampling methods. Data from both calves revealed a pattern of increasing independence as they aged, but there were significant differences between the two calves. Suckling rates, mean suckles per bout, suckling bout rates, and bout durations for the male calf were higher than those for the female calf throughout the study. These frequencies declined significantly over time in the male's case but not in the female's case. Her suckling durations (lock-on time) were longer than his. The male spent more time in infant position (under the mother) than the female calf and less time swimming in echelon position (alongside the mother). Over time, the male spent less time in infant position, and the female calf spent more time socializing and less time echelon swimming. Both calves decreased the amount of time spent close to their mothers over the 9 week period, and the mothers decreased their role in proximity maintenance over time. We suggest that factors related to maternal primiparity caused the male calf to develop an effective compensatory response of frequent nursing and spending more time in infant position. Both calves survived and were healthy at the end of the observation period. © 1995 Wiley-Liss, Inc.     

Preventing physical interactions between parturient ewes and their neonate differentially impairs the development of maternal responsiveness and selectivity depending on maternal experience

The present study investigated whether deprivation of nursing or of any physical interaction with the lamb impairs the onset of maternal responsiveness and the establishment of selectivity in primiparous and multiparous ewes. Just after parturition, ewes could interact freely with their lamb, or could only lick their lamb but not nurse them, or could neither lick nor nurse them for the first 4 h. At 4 h, mothers were successively observed for 3 min with an alien lamb and then with their own lamb. Only 5/14 primiparous mothers accepted their own lamb following deprivation of all physical contact whereas all multiparous mothers did so (19/19). Also, deprivation of all physical contact resulted in a significantly higher proportion of multiparous mothers accepting an alien lamb (6/18) than following deprivation of nursing only (0/19) indicating an impairment in selectivity. Finally, there was no indication that preventing only nursing led to a deficit either in maternal responsiveness or selectivity, neither in primiparous nor in multiparous ewes. These findings underline the importance of perception of olfactory cues from amniotic fluids through licking and/or physical contact and interacting with the lamb for the development of maternal responsiveness and selectivity.     

The effects of primiparity on reproductive performance in the brown bear

We studied the effects of primiparity on litter size, offspring size, and cub loss in brown bears (Ursus arctos) in two study areas (north, south) in Sweden from 1987 to 2006. Sexually selected infanticide (SSI) has been suggested previously as a mortality factor in our study populations. Females in the south became primiparous earlier than females in the north. Primiparous females had significantly smaller litters of cubs than multiparous females. We found no evidence that primiparity was costly in terms of the interlitter interval. Primiparous mothers had a higher probability of cub loss than multiparous mothers. The probability of cub loss was analyzed separately for the pre-mating and the mating season. The probability of cub loss by primiparous females in the pre-mating season increased with both increasing population density and deteriorating food conditions, whereas the probability of cub loss during the mating season decreased with increasing age of primiparity and increased with male turnover (a variable predicting SSI). The temporal patterns of cub loss by primiparous females suggested that the critical times for reproductive success by primiparous females were the pre-mating season (from birth to shortly after leaving the den) and the mating season. Cub loss in these periods was independent and caused by different factors. Cub loss before the mating season seemed to be most influenced by food conditions, whereas that during the mating season appeared to be caused by SSI.