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PubMed2005

The evolution of meiosis: recruitment and modification of somatic DNA-repair proteins.

Several DNA-damage detection and repair mechanisms have evolved to repair double-strand breaks induced by mutagens. Later in evolutionary history, DNA single- and double-strand cuts made possible immune diversity by V(D)J recombination and recombination at meiosis. Such cuts are induced endogenously and are highly regulated and controlled. In meiosis, DNA cuts are essential for the initiation of homologous recombination, and for the formation of joint molecule and crossovers. Many proteins that function during somatic DNA-damage detection and repair are also active during homologous recombination. However, their meiotic functions may be altered from their somatic roles through localization, posttranslational modifications and/or interactions with meiosis-specific proteins. Presumably, somatic repair functions and meiotic recombination diverged during evolution, resulting in adaptations specific to sexual reproduction. (c) 2005 Wiley Periodicals, Inc.

Animals↗
PubMed2007

Risk for breast cancer among women with endometriosis.

Although several risk factors are common to endometriosis and breast cancer, the results of observational studies of an association have so far been inconsistent. We evaluated the relationship between endometriosis and breast cancer on the basis of data on selected cancers and medical histories from the Danish nationwide cancer and hospital registries used in a large case-cohort study. A total of 114,327 women were included in the study of whom 1,978 women had received a diagnosis of endometriosis and 16,983 had had a diagnosis of breast cancer between 1978 and 1998. Of the women with endometriosis, 236 subsequently received a diagnosis of breast cancer. The crude overall rate ratio for breast cancer after endometriosis was 1.00 and after adjustment for reproductive factors, calendar-period, bilateral oophorectomy and benign breast disease, the rate ratio was 0.97 (95% confidence interval, 0.85-1.11). The risk for breast cancer increased with age at diagnosis of endometriosis, so that women in whom endometriosis was diagnosed at a young age (approximately <40 years) had a reduced risk for breast cancer and women in whom endometriosis was diagnosed at older ages (approximately > or =40 years) tended to have an increased risk for breast cancer. The reduced risks observed among young women may reflect their exposure to drugs with antiestrogenic effects. The increased risk associated with endometriosis among postmenopausal women may be due to common risk factors between postmenopausal endometriosis and breast cancer or an altered endogenous estrogen.

Adult↗
PubMed1995

Manipulating melatonin in red deer (Cervus elaphus): differences in the response to food restriction and lactation on the timing of the breeding season and prolactin-dependent pelage changes.

In this study, we investigated the influence of food availability and lactation upon seasonality in red deer. This was examined by testing the hypothesis that advancing the timing of breeding and autumn moult using the hormone melatonin will be prevented when the food availability of lactating hinds is severely restricted. This hypothesis was rejected. Implanting 1 g of melatonin between June 22 and November 30 resulted in advances in the timing of the onset of ovarian activity and winter coat growth of 18 and 35 days, respectively. Whilst the onset of ovarian activity was unaffected by lactation and restricted food availability, these factors significantly delayed the winter coat growth by 20 days. The date of onset of winter primary fibre growth was negatively correlated to plasma concentrations of the hormone prolactin in July. We suggest that seasonal changes in the growth of primary hair fibres are modified by two mechanisms: the increasing duration of melatonin secretion, as day lengths decline, which depresses prolactin secretion, and low nutrition, which elevates prolactin secretion in lactating deer. To conclude, we have demonstrated that the sensitivity of red deer to photoperiodic influences is preserved in lactating animals at low levels of nutrition, and that the timing of the onset of the breeding season and winter coat growth differ detectably in their sensitivity to nutrition and lactation.

Animal Feed↗
PubMed1993

Changes in serum C-reactive protein levels in dogs with various disorders and surgical traumas.

The serum levels of C-reactive protein (CRP) produced as an inflammatory response in dogs with various disorders and surgical traumas were measured by enzyme-linked immunoabsorbent assay and slide reversed passive latex agglutination test (RPLA). The CRP levels were greatly increased 1-2 days after surgery in most of the dogs (n = 29) subjected to surgery. These levels had markedly decreased by the time the sutures were removed. In dogs with various disorders (n = 58), the serum CRP levels at first diagnosis were high in infectious diseases. In dogs from which paired serum samples were examined, the serum CRP usually showed a decrease with improvement in the condition (n = 11) or a terminal increase (n = 4) but, conversely, some showed an increase with improvement in the condition (n = 3).

Animals↗
PubMed2004

Floral scent emission and pollinator attraction in two species of Gymnadenia (Orchidaceae).

We investigated scent composition and pollinator attraction in two closely related orchids, Gymnadenia conopsea (L.) R.Br. s.l. and Gymnadenia odoratissima (L.) Rich. in four populations during the day and night. We collected pollinators of both species using hand nets and sampled floral odour by headspace sorption. We analysed the samples by gas chromatography with mass spectrometry to identify compounds and with electroantennographic detection to identify compounds with physiological activity in pollinators. In order to evaluate the attractiveness of the physiologically active compounds, we carried out trapping experiments in the field with single active odour substances and mixtures thereof. By collecting insects from flowers, we caught eight pollinators of G. conopsea, which were members of four Lepidoptera families, and 37 pollinators of G. odoratissima, from five Lepidopteran families. There was no overlap in pollinator species caught from the two orchids using nets. In the scent analyses, we identified 45 volatiles in G. conopsea of which three (benzyl acetate, eugenol, benzyl benzoate) were physiologically active. In G. odoratissima, 44 volatiles were identified, of which seven were physiologically active (benzaldehyde, phenylacetaldehyde, benzyl acetate, 1-phenyl-2,3-butandione, phenylethyl acetate, eugenol, and one unknown compound). In field bioassays using a mixture of the active G. odoratissima compounds and phenylacetaldehyde alone we caught a total of 25 moths, some of which carried Gymnadenia pollinia. A blend of the active G. conopsea volatiles placed in the G. odoratissima population did not attract any pollinators. The two orchids emitted different odour bouquets during the day and night, but G. odoratissima showed greater temporal differences in odour composition, with phenylacetaldehyde showing a significant increase during the night. The species differed considerably in floral odour emission and this differentiation was stronger in the active than non-active compounds. This differentiation of the two species, especially in the emission of active compounds, appears to have evolved under selection for attraction of different suites of Lepidopteran pollinators.

Adaptation, Physiological↗
PubMed2006

Local adaptation in the monocarpic perennial Carlina vulgaris at different spatial scales across Europe.

Spatial variation in environmental conditions can lead to local adaptation of plant populations, particularly if gene flow among populations is low. Many studies have investigated adaptation to contrasting environmental conditions, but little is known about the spatial scale of adaptive evolution. We studied population differentiation and local adaptation at two spatial scales in the monocarpic grassland perennial Carlina vulgaris. We reciprocally transplanted seedlings among five European regions (northwestern Czech Republic, central Germany, Luxembourg, southern Sweden and northwestern Switzerland) and among populations of different sizes within three of the regions. We recorded survival, growth and reproduction over three growing periods. At the regional scale, several performance traits and the individual fitness of C. vulgaris were highest if the plants were grown in their home region and they decreased with increasing transplant distance. The effects are likely due to climatic differences that increased with the geographical distance between regions. At the local scale, there were significant interactions between the effects of the population of origin and the transplant site, but these were not due to an enhanced performance of plants at their home site and they were not related to the geographical or environmental distance between the site of origin and the transplant site. The size of the population of origin did not influence the strength of local adaptation. The results of our study suggest that C. vulgaris consists of regionally adapted genotypes, and that distance is a good predictor of the extent of adaptive differentiation at large scales ( > 200 km) but not at small scales. We conclude that patterns of local adaptation should be taken into account for the efficient preservation of genetic resources, when assessing the status of a plant species and during conservation planning.

Adaptation, Biological↗
PubMed1983

Testosterone stimulation of DNA-dependent DNA polymerase activities in the cloacal and uropygial glands of the male quail (Coturnix coturnix japonica).

DNA polymerase alpha and beta activities were studied and compared in the cloacal gland and the uropygial gland (sebaceous-like gland) taken from castrated quails after testosterone administration. In the cloacal gland, testosterone induced an important increase in DNA polymerase alpha while DNA polymerase beta was not found to be altered. In the uropygial gland, testosterone induced a cyclic variation of DNA polymerase alpha activity which may relate to the holocrine function of this gland.

Animals↗
PubMed1984

Prolactin is associated with the development of photorefractoriness in intact, castrated, and testosterone-implanted starlings.

Using radioimmunoassays, prolactin, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were measured in the plasma of intact, castrated, and testosterone-implanted male starlings. Two groups of birds (intact and castrated males) were transferred when photosensitive from short (8-hr) to long (16-hr) day lengths; in both cases plasma prolactin levels increased steadily reaching a peak after 5 weeks of photostimulation, at the time of the onset of photorefractoriness . Three groups ( intacts , castrates, and castrates implanted with Silastic capsules containing testosterone) were exposed to day lengths increasing by 30 min per week from 8 to 16 hr. Again, prolactin levels increased in a similar fashion in all three groups at the time of refractoriness, which occurred when the day length reached 15-16 hr. Thus the timing of photorefractoriness and the associated rise in prolactin secretion which occur in response to photostimulation do not depend upon the presence of the gonads and are not affected when testosterone is maintained at a constant high level. Nor is the increase in prolactin altered when the cycle of gonadotrophin secretion which normally precedes it is completely suppressed by the implantation of a testosterone capsule. It would seem that prolactin secretion in the starling is stimulated by transfer from short to long day lengths, but not as a consequence of high gonadotrophin or androgen secretion rates.

Animals↗
PubMed1984

Thyroidectomy prevents the development of photorefractoriness and the associated rise in plasma prolactin in starlings.

Intact and radiothyroidectomized male starlings were transferred from short (8-hr) to long (16-hr) day lengths and measurements made of testicular development and of plasma prolactin concentrations. In intact birds the testes reached full maturity within 3 weeks and regressed after 6 weeks of photostimulation, indicative of the development of photorefractoriness . Prolactin levels increased gradually, reaching maximal values (25.2 +/- 4.7 ng/ml compared with 1.2 +/- 0.2 ng/ml before photostimulation) at the time of testicular regression. Testicular growth was normal in the thyroidectomized birds, but in three of eight testes remained fully mature for at least 1 year, and prolactin remained low (below 2.0 ng/ml) during this entire time. The testes of the other five thyroidectomized birds did regress partially, accompanied by a corresponding increase in prolactin, although the testes subsequently regrew . Removal of the testes from thyroidectomized birds after 1 year on long days resulted in a marked rise in plasma FSH, indicating that these birds were indeed not photorefractory ; FSH levels in the refractory-intact starlings remained low after castration. These results confirm that the presence of an intact thyroid gland is essential for the development of photorefractoriness and for the release of prolactin which normally follows photostimulation.

Animals↗
PubMed1988

Uterine metabolism of estradiol in vivo during early pseudopregnancy in the rat.

We measured the concentration of [3H]estradiol (E2) and its conversion to [3H]estrone (E1) in endometrium and myometrium at diestrus, estrus, and Days 2-6 of pseudopregnancy (PSP) in the rat. Animals (N = 5-10/group) were anesthetized with pentobarbital and a constant infusion of [3H]E2 initiated via a jugular vein. Following attainment of isotopic equilibrium, a blood sample was obtained from the inferior vena cava, the endometrium and myometrium isolated, and [3H]E2 and [3H]E1 content determined after purification by paper chromatography. The metabolic clearance rate of E2 and the peripheral conversion of E2 to E1 (% Cr E2----E1), remained relatively constant throughout the study period. Regardless of the reproductive status of the rat, endometrial and myometrial [3H]E2 and [3H]E1 concentrations (cpm/g) were greater (P less than 0.001) than respective values (cpm/ml) in serum. At estrus, the concentration of [3H]E2 in the endometrium was lower (P less than 0.05) than that at diestrus. In contrast, endometrial % Cr E2----E1 and weight of the endometrium were both greater (P less than 0.05) at estrus than at diestrus. Similar patterns were measured in the myometrium. During PSP, the concentration of [3H]E2 in the endometrium increased (P less than 0.05) from Day 2 to Day 6 whereas concentrations in the myometrium remained relatively constant. Endometrial weight increased (P less than 0.05) between Days 2-4 of PSP and was associated with a concomitant decrease (P less than 0.05) in the % Cr E2----E1 from 59 to 22%. The % Cr E2----E1 in the myometrium (2-4%) was constant between Days 2-4 of PSP but increased to 10% by Day 6 in association with a decrease (P less than 0.05) in weight of the myometrium. We have demonstrated in vivo that growth and differentiation of the uterine endometrium during early pseudopregnancy in preparation for implantation/deciduogenesis is associated with decreased endometrial % Cr E2----E1. Because ovarian E2 production is markedly decreased during early PSP, we suggest that a decrease in uterine metabolism of E2 may act, in part, to maintain endometrial E2 at concentrations sufficient to permit receptor interaction.

Animals↗
PubMed1978

A look at the basic correlates of longevity: is longevity a superficial trait?

Nature appears to have distributed life spans, whether long or short, entirely upon the possession or non-possession of a few physiologically superficial characteristics, namely, immunity of mature, full-sized specimens from the effects of: (1) predation, (2) competition, (3) fire, (4) disease, and (5) the existence of a definite usefulness for long life spans in bridging lengthy periods unfavorable to the reproduction and/or maturation of offspring. Extremely strong correlations are presented in proof of the above relationships. Since longevity mechanisms can closely correlate to superficial traits, it is unlikely that they comprise an integral part of basic structural or biochemical processes. In the case of trees, all five of the above traits are apparently required for the achievement of potential life spans in excess of 1000 years. By contrast, the longest live animal species appear to fully possess only (1) and (3) of the five prerequisite traits above. This observation may fully account for the fact that maximum life spans of trees are 30-40 times greater than those of the longest lived animals.

Animals↗
PubMed1993

Alteration of the bed nucleus of the stria terminalis (BNST) in young female Djungarian hamsters (Phodopus campbelli) exposed to adult males.

Central components of the vomeronasal system appear to mediate extrahypothalamic control of gonadotropin release during male-induced acceleration of puberty onset in female rodents. In order to describe the bed nucleus of the stria terminalis (BNST) and to determine whether this component of the vomeronasal system is altered following early puberty onset, the anterior BNST of female Djungarian hamsters (Phodopus campbelli) was subdivided into three regions: medial, lateral, and ventral. The cross-sectional area, soma size, and neuronal density of each subdivision was compared among female hamsters in three groups: (1) young females showing accelerated reproductive development following a period of housing with an adult male, (2) young females matched by age with the accelerated females but housed alone during the same period, and (3) older females at the age of spontaneous puberty. Females housed with an adult male and undergoing accelerated puberty onset had significantly smaller lateral anterior BNST subdivisions than females housed alone for the same period (10 days following weaning) or housed alone until the age of spontaneous puberty onset (25 days following weaning). The size of the ventral and medial subdivisions was not different in the three groups. Furthermore, although soma size and neuronal density differed markedly among the anterior BNST subdivisions, these subdivision characteristics were similar in the accelerated, prepubertal, and older pubertal females. Our finding demonstrates that a central component of the vomeronasal system undergoes neuroanatomical alteration in response to environmental stimuli and recommends further examination of the BNST during this dynamic ontogenetic period.

Animals↗