Maternal immunization to paternal antigens in multiparous mice.

Mice of the CBA strain which had given birth to five litters sired by males of a different H-2 type (C57BL/10) showed evidence of immunization to paternal antigens, in that the numbers of lymphocytes forming alloclusters with paternal erythrocytes were significantly elevated. On the other hand, the graft-versus-host responsiveness of maternal splenic lymphocytes to paternal antigens remained virtually unchanged, showing only a slight increase at Day 8 of the assay.     

Time of ovulation in nulliparous and multiparous goats

Fifteen nulliparous and nine multiparous Serrana goats were used, through two successive oestrous cycles, in order to characterize their ovulation time with regard to the number of ovulations after induced and natural oestrus during the breeding season. The onset of oestrus was detected by the amount of vasectomized bucks after oestrus synchronization with prostaglandin, given 10 days apart, and in the following two expected natural oestrus. The preovulatory LH peak was determined from blood samples collected 0, 4, 8, 12, 16, 20 and 24 h after onset of oestrus. A transrectal ovarian ultrasound scanning was performed 20, 24, 28, 32, 36, 40, 44 and 60 h after onset of oestrus, for the detection of ovulations by means of the disappearance of large follicles (>4 to 5 mm). Single ovulations were observed in 76% of oestrous periods in nulliparous goats and in 18% of nulliparous goats. The onset of oestrus to LH peak interval was lower in nulliparous (12.1 ± 0.9 h, n = 38) than in multiparous (15.6 ± 1.0 h, n = 22, P < 0.05) goats with no oestrus interaction effects (P > 0.05). The LH peak to first ovulation interval was higher after natural (18.9 ± 0.7 h, n = 36) than after induced (15.8 ± 1.2 h, n = 24, P < 0.05) oestrus. The onset of oestrus to total ovulation interval was influenced by parity (P < 0.01) and oestrus type (P < 0.05) with a length of 30.1 ± 1.1 h (n = 15) and 33.4 ± 1.5 h (n = 9) for induced oestrus of nulliparous and multiparous goats, respectively, and 32.5 ± 1.0 h (n = 23) and 36.5 ± 1.1 h (n = 13) for natural oestrus of nulliparous and multiparous goats, respectively. The onset of oestrus to first ovulation interval was not influenced by parity, but an interval of 8.0 ± 1.6 h was observed between the first and second ovulations in polyovulatory oestrus. Consequently, nulliparous goats that are predominantly monovular ovulate earlier than multiparous goats that are predominantly polyovulatory. In conclusion, significant differences occurred in the number and time of ovulations between nulliparous and multiparous goats. More research is necessary for a deeper understanding of the mechanisms regulating monovularory and polyovulatory oestrous cycles regarding the parity of goats.     

Space,density and extra-pair matings have opposing impacts on male and female reproductive success

Many territorial species have a mating system characterized by males establishing home ranges in the breeding grounds prior to females, resulting in males competing for territories and females choosing a mate upon their arrival. It remains unknown, however, how the outcomes of decisions surrounding territory establishment and mate choice are influenced by the spatial configuration of the breeding grounds. We use a spatially explicit, individual-based model to investigate the sex-specific effects of these decisions on reproductive success. In our model, males that arrive earlier obtain higher quality territories and improve their chances for extra-pair copulations. Females can choose their mate to maximize the quality of the male or to attempt to minimize the density of other females near their nesting site to avoid competition. Females therefore face a tradeoff between high-density regions around high-quality males and low-quality males in areas of low competition. Our model predicts a negative correlation between male and female reproductive success under a wide range of conditions when the majority of the territories are on the margins of the breeding area. Most notably, this sexual conflict arises as an edge effect suggesting that fragmentation of breeding habitats could impact the consequences of mate choice in many species with territorial breeding habits.     

Histochemical and stereological analysis of the levator ani (pubocaudal) muscle in nulliparous and multiparous beagles

Fiber-type composition and several stereological parameters of the levator ani (pubocaudal) muscle were evaluated in five nulliparous and five multiparous beagles using myosin ATPase-histochemistry and systematically selected muscle cross-sections. With respect to the narrow canine pelvic cavity, this study was also undertaken to determine whether vaginal birth of at least seven litters causes similar neuromuscular changes in the canine levator ani (pubocaudal) muscle analoguous to those seen in the pelvic floor muscles of women after vaginal delivery. The canine pubocaudal muscle is comprised of approximately equal amounts of slow twitch type I and fast twitch type II (IIA, IIS) fibers. The muscles of both the nulliparous and multiparous beagles did not display any signs indicative of denervation or myopathology. The multiparous dogs exhibited significantly increased mean absolute muscle (1720 mm(3)) and total fiber-type I volumes (850 mm(3)) as well as relevantly increased mean diameter of type I fibers (72.0 microm) when compared with the nulliparous group. The canine levator ani (pubocaudal) muscle is not pathologically affected by vaginal deliveries and seems to adapt to numerous successive pregnancies and births through fiber-type I hypertrophy.     

Lanosterol and cholesterol have different effects on phospholipid acyl chain ordering

2H nuclear magnetic resonance (2H-NMR) spectra of dioleoylphosphatidylcholine labelled at positions 9 and 10 in the acyl chains of the phospholipid were obtained in the presence of cholesterol and lanosterol. The spectra show in all cases three quadrupole splittings. One is due to the deuterium on position 10 of the sn-1 chain and another to the deuterium on position 10 of the sn-2 chain. The third deuterium quadrupole splitting arises from the deuterium at position 9 of both chains. Cholesterol, at increasing concentration, produces an increase in the quadrupole splitting from position 9, corresponding to an increase in order of that C-D bond segment arising from the inclusion of cholesterol in the membrane. Little effect is noted on the quadrupole splittings arising from position 10 of either chain. Lanosterol appears to have no effect on the quadrupole splittings from position 9. Lanosterol, likewise, has no effects on the quadrupole splittings from position 10 of both chains. These data therefore suggest little disorganization of the membrane structure due to the 14-methyl group. However, the 14-methyl group prevents lanosterol from causing the increase in motional order of the phospholipid hydrocarbon chains characteristic of cholesterol.     

Heat acclimation and heat stress have different effects on cholinergic-induced calcium mobilization

There is evidence that the signal transduction array responsible for the secretion of water in evaporative cooling by the submaxillary gland of the rat is subject to heat acclimatory responses. The objectives of the present study were 1) to examine whether heat acclimation affects intracellular Ca(2+) mobilization and, in turn, submaxillary glandular responsiveness; 2) to assess whether the acclimatory responses differ from those evoked on heat stress (HS). Experiments were conducted on submaxillary glands of rats acclimated at 34 degrees C for 0, 2 [short-term heat acclimation (STHA)], and 30 [long-term heat acclimation (LTHA)] days. The resting cytosolic calcium concentration ([Ca(2+)](c)) and the carbamylcholine-evoked calcium signal ([Ca(2+)](s)) of dispersed glandular cells were measured using the fluorescent dye fura 2 AM. Inositol-1,4,5-trisphosphate (IP(3))-sensitive endoplasmic reticulum Ca(2+) stores were determined in permeabilized cells using fura 2 potassium salt. STHA resulted in a drop in both [Ca(2+)](s) and IP(3)-sensitive Ca(2+) stores. On LTHA, the [Ca(2+)](s) amplitude reverted to the preacclimation value, whereas the IP(3)-sensitive Ca(2+) stores remained low. The drop in [Ca(2+)](s) on STHA is in accord with the decreased glandular output (measured by (86)Rb efflux) observed during this acclimation phase. However, after LTHA the enhanced glandular output despite reduced [Ca(2+)](s) levels suggests an increased efficiency of cellular secretory mechanisms in that group. Collectively, the alterations in [Ca(2+)](s) support our biphasic acclimation model (Horowitz M, Kaspler P, Marmari Y, and Oron Y. J Appl Physiol 80: 77--85, 1996.). In nonacclimated glands, HS caused an elevation in [Ca(2+)](s) coincidentally with a decrease in the IP(3) Ca(2+) stores. In contrast, [Ca(2+)](s) in both STHA and LTHA glands was not affected by HS, despite a marked increase in the IP(3)-sensitive Ca(2+) stores in the LTHA glands. The opposing responses to HS and heat acclimation in calcium signaling and stores confirm the specificity of each process.     

Induction and synchronization of ovulations of nulliparous and multiparous sows with an injection of gonadotropin-releasing hormone agonist (Receptal)

The objective of this study was to determine if administration of a set dose (10 μg) of a gonadotropin-releasing hormone agonist, buserelin (Receptal; Rc), at set times after altrenogest (Regumate; RU) treatment or after weaning was able to induce and synchronize ovulation in female swine (gilts and sows). The pubertal (n = 187) gilts were allocated to four groups, all synchronized with RU. Group 1 (RU) was inseminated twice at detected estrus, Group 2 (RU+Rc120) and Group 4 (RU+Rc104) received 10 μg Rc at 120 or 104 h after the end of RU treatment, respectively, and Group 3 (RU+eCG+Rc104) was treated with 800 IU equine chorionic gonadotropin (eCG) at 24 h and Rc 104 h after the end of RU treatment, respectively. Gilts were inseminated twice at predetermined times, namely 144 and 168 h (Group 2), 128 and 144 h (Group 3), and 144 and 152 h (Group 4) after the end of RU treatment, respectively. Pregnant gilts were slaughtered at 30 d. Administration of Rc 104 h after the end of RU feeding synchronized ovulation over a 24-h time window in 97.9% and 100% of the gilts of Groups 3 and 4, respectively, whereas Rc administration at 120 h (Group 2) only successfully synchronized 88.9% of the gilts over 24 h. Ovulation rates of gilts of Groups 2 and 4 were similar to that of the control group. Pregnancy rates were numerically higher in Groups 2 and 3 (92% and 96%, respectively) compared with those of Groups 1 and 4 (84% and 81%, respectively). Combination of eCG with Rc administration at 104 h (Group 3) increased ovulation rate (+4 CL) but decreased embryo survival to 62% at Day 30. The weaned sow experiment involved 61 sows of a range of parities (2.7 ± 0.9), allocated to two control groups (Control 104 group and Control 94 group) and two treated groups (Rc104 group and Rc94 group), which received 10 μg Rc at 104 and 94 h after weaning, respectively. The females were inseminated at detected estrus. All pregnant sows farrowed. After treatment with Rc 94 h after weaning, 100% of sows ovulated over a 24-h time window versus only 68.7% of controls. Farrowing rate and litter size of the sows treated with Rc at that time were unaffected compared with that of control sows. In contrast, Rc administration at 104 h after weaning may have been too late; only 66.7% of the treated sows ovulated during a 24-h period. This proportion was numerically lower but not significantly different than that for control sows. Farrowing rate and litter size of treated sows were not significantly different than that of controls. Administration of Rc at the dose and times selected in this study tightened synchrony of ovulation in gilts and in sows after weaning. It remains to be established if such a synchrony is suitable to obtain good fertility after a single artificial insemination at a predetermined time.     

Low frequency electric and magnetic fields have different effects on the cell surface

There is a considerable controversy over the nature of weak electromagnetic-field effects in living organisms. Part of the controversy can be traced to a lack of understanding of whether electric or magnetic fields are involved in producing bioeffects. We find that both 60 Hz electric and magnetic fields alter the cell surface of Physarum polycephalum. Exposure to electric fields increases the negative charge on the cell surface while magnetic-field exposure decreases the hydrophobic character of the surface. These effects appear to be additive and independent of the waveform of the applied fields.     

研究性学习中不同研究方法对师专生生物学兴趣影响的差异研究

研究性学习是我国当前基础教育改革的一个亮点、热点和难点,其中有很多值得研究的问题。就研究性学习中研究方法的不同对师专生的生物学兴趣差异的影响进行了探讨。     

Immunohistochemical expression of collagen types I, III, IV and alpha-actin in the uterine horns of nulliparous and multiparous beagles

Collagen and smooth muscle cells play essential roles in the remodelling of uterine tissue during pregnancy and involution. To investigate the immunoreactivity and distribution pattern of collagen types I, III, IV and smooth muscle alpha-actin resulting from these processes, two homogenous groups of nulliparous and multiparous beagles were evaluated by immunohistochemistry. Immunostaining patterns of collagens I and III delineated the uterine connective tissue fibers and revealed their dual presence within fibers of both beagle groups. Collagen III staining, in particular, was more pronounced and especially evident in superficial fiber sections. The numerous, large arteries in the myometrial stratum vasculare of multiparous uteri exhibited a highly thickened intima, which distinctly expressed type I and III collagens. Intense collagen IV immunolabeling was discernable in the basement membranes of vascular endothelia and smooth muscle cells. Staining of the basement membranes of the luminal and glandular epithelia, conversely, was either absent or very weak. No difference in the immunoreactivity and distribution of the assessed collagens and actin could be detected between nulliparous and multiparous dogs. Overall, and with the exception of sclerotic arteries, immunohistochemical analysis revealed that the expression of uterine collagens and actin does not change in the uterus of multiparous beagles, even after seven elapsed pregnancies.     

Wild O chromosomes of Drosophila subobscura from different geographic regions have different effects on viability

By means of the marker strain Va/Ba wild chromosomes O of Drosophila subobscura were extracted from eight natural populations situated on a north-south gradient from Sweden or Scotland to Tunesia. Lethal frequencies and viability effects of the wild chromosomes O were studied in homozygous and random heterozygous combinations. In accordance with results from other Drosophila species random heterozygotes were always more viable than homozygotes. The viability-determining polygene system proved, however, dominant to some degree. Geographic differences became apparent especially with respect to three different characteristics: (1) The lethal frequencies for chromosomes O from central populations are higher than for those from northern and southern marginal populations; (2) Mean viabilities of non-lethal homozygotes and random heterozygotes are lower for central than for marginal populations; (3) The increase of viability through heterozygosity is more pronounced in the northern populations than in the others. The differences are thought to be mainly due to differences in the adaptation strategy of marginal and central populations. The viability fitness components seem of more importance for the marginal populations while fertility components may be of greater weight under central conditions. The geographic variability of the viability polygene system is finally compared with that of other genetic traits in D. subobscura.     

Progesterone and norethisterone have different effects on tachykinin-like immunoreactivity in rat cortex and striatum

OBJECTIVE: The purpose of this study was to investigate the effects of progesterone and the most commonly prescribed synthetic progestogen, norethisterone, on regional immune-like reactivity of neuropeptide Y (NPY), substance P (SP), neurokinin A (NKA) and neurotensin (NT) in brains of female ovariectomized estradiol-substituted rats. Results: Norethisterone+estradiol-treated rats had 44% lower SP levels compared with estradiol-only-treated in frontal cortex and 20% lower NKA levels in comparison with progesterone+estradiol-treated in frontal cortex. Progesterone+estradiol-treated rats had 66% lower SP levels in striatum in comparison with both estradiol-only-treated and norethisterone+estradiol-treated. No significant results were found for NPY and NT. CONCLUSION: Progesterone and the synthetic progestogen, norethisterone, have different effects on SP- and NKA-like immunoreactivity in rat cortex and striatum.The effects of NET on SP- and NKA-like immunoreactivity in frontal cortex may contribute to the mood effects ascribed to this progestogen in clinical usage.     

Nitric oxide compounds have different effects profiles on human articular chondrocyte metabolism

Introduction

The pathogenesis of osteoarthritis (OA) is characterized by the production of high amounts of nitric oxide (NO), as a consequence of up-regulation of chondrocyte-inducible nitric oxide synthase (iNOS) induced by inflammatory cytokines. NO donors represent a powerful tool for studying the role of NO in the cartilage in vitro. There is no consensus about NO effects on articular cartilage in part because the differences between the NO donors available. The aim of this work is to compare the metabolic profile of traditional and new generation NO donors to see which one points out the osteoarthritic process in the best way.

Methods

Human healthy and OA chondrocytes were isolated from patients undergoing joint replacement surgery, and primary cultured. Cells were stimulated with NO donors (NOC-12 or SNP). NO production was evaluated by the Griess method, and apoptosis was quantified by flow cytometry. Mitochondrial function was evaluated by analysing respiratory chain enzyme complexes, citrate synthase (CS) activities by enzymatic assay, mitochondrial membrane potential (Δψm) by JC-1 using flow cytometry, and ATP levels were measured by luminescence assays. Glucose transport was measured as the uptake of 2-deoxy-[³H]glucose (2-[³H]DG). Statistical analysis was performed using the Mann-Whitney U test.

Results

NOC-12 liberates approximately ten times more NO₂^- than SNP, but the level of cell death induced was not as profound as that produced by SNP. Normal articular chondrocytes stimulated with NOC-12 had reduced activity from complexes I, III y IV, and the mitochondrial mass was increased in these cells. Deleterious effects on ΔΨm and ATP levels were more profound with SNP, and this NO donor was able to reduce 2-[³H]DG levels. Both NO donors had opposite effects on lactate release, SNP diminished the levels and NOC-12 lead to lactate accumulation. OA chondrocytes incorporate significantly more 2-[³H]DG than healthy cells.

Conclusions

These findings suggest that the new generation donors, specifically NOC-12, mimic the OA metabolic process much better than SNP. Previous results using SNP have to be considered prudently since most of the effects observed can be induced by the interactions of secondary products of NO.     

Introduced and native herbivores have different effects on plant composition in low productivity ecosystems

Questions

Understanding how livestock grazing alters plant composition in low productivity environments is critical to managing livestock sustainably alongside native and introduced wild herbivore populations. We asked four questions: (1) does recent livestock and rabbit grazing reduce some plant attributes more strongly than others; (2) does grazing by introduced herbivores (i.e. livestock and rabbits) affect plants more strongly than native herbivores (i.e. kangaroos); (3) do the effects of recent livestock grazing differ from the legacy effects of livestock grazing; and (4) does the probability of occurrence of exotic plants increase with increasing net primary productivity (NPP)?

Location

South‐eastern Australia.

Methods

We measured the recent grazing activity of co‐occurring livestock (cattle, sheep, goats), rabbits and kangaroos by counting faecal pellets; historic grazing activity by measuring livestock tracks; and derived NPP from satellite imagery. We used a hierarchical GLMM to simultaneously model the presence or absence (i.e. probability of occurrence) of all plant species as a function of their attributes (growth form, lifespan and origin) to assess their average response to recent grazing, historic grazing and productivity in a broad‐scale regional study.

Results

Recent and historic livestock grazing, rabbit grazing and increasing NPP reduced the average probability of occurrence of plant species, although responses varied among plant attributes. Both recent and historic livestock grazing strongly reduced the average probability of occurrence of native species, and forbs and geophytes, but differed in their relative effects on other growth forms. Recent livestock grazing, rabbit grazing and NPP had similar effects, strongly reducing native species and forbs, geophytes, shrubs and sub‐shrubs. The overall effects of recent kangaroo grazing were relatively weak, with no clear trends for any given plant attribute.

Conclusion

Our results highlight the complex nature of grazing by introduced herbivores compared with native herbivores on different plant attributes. Land managers need to be aware that domestic European livestock, rabbits and other free‐ranging introduced livestock such as goats have detrimental impacts on native plant communities. Our results also show that kangaroo grazing has a relatively benign effect on plant occurrence.     

Two closely related nickel complexes have different effects on DNA damage and cell viability

Nickel is considered a weak carcinogen. It is known to interact with DNA and DNA-binding proteins. The ability of certain nickel compounds to cleave DNA has been exploited mainly for research purposes and less for developing new anticancer drugs. Here we compare the interactions of two closely related nickel complexes, [NiCR]2+ and [Ni(CR-2H)]2+, with DNA. CR stands for 2,12-dimethyl-3,7,11,17-tetraazabicyclo-[11.3.1]-heptadeca-1(17),2,11,13,15-pentaene. [NiCR]2+ has been used in the past as a structure-specific probe for RNA and DNA oligonucleotides in the presence of oxidizing agent but little is known about the biological effects of either complex. Our results show that [Ni(CR-2H)]2+ can damage DNA in vivo and in vitro in the absence of an added oxidizing agent and has an IC50 of 70 microM in human breast cancer cells whereas [NiCR]2+ and NiCl2 do not exhibit significant cytotoxicity. However, both [NiCR]2+ and [Ni(CR-2H)]2+ bind to the minor groove of double-stranded DNA.