Interacting evolutionary constraints in pelvic reduction of threespine sticklebacks, Gasterosteus aculeatus (Pisces, Gasterosteidae)

The pelvic girdle of Gasterosteus aculeatus is normally a complex and robust structure that varies moderately among and within populations, but in several populations it occurs as a vestigial series. Based on 14 Recent and fossil populations from North America and Scotland, three general patterns of intrapopulation variation of vestigial pelvic structures can be recognized. In most cases of pelvic reduction, the size and complexity of the pelvic girdle are reduced mostly by progressive truncation of distal structures, but two patterns of distal truncation occur. Paedomorphosis appears to play a role in all cases of pelvic reduction, but in a fossil assemblage and one extant population it accounts for most of the structural simplification.
Pelvic reduction in populations of Gasterosteus depends on an interaction between natural selection, which appears to determine whether or not pelvic reduction occurs, and phylogenetic constraint (especially developmental constraint), which strongly influences the form of pelvic vestiges. The empirical difficulty of discriminating between phylogenetic constraint and effects of natural selection, and the potential for phylogenetic constraint to produce homoplasy are discussed. Pelvic reduction apparently has been a recurrent phenomenon in Gasterosteus since at least the early Pliocene, but it has not resulted in evolution of a separate lineage of 'pelvicless' sticklebacks because such populations are restricted to lakes, which are ephemeral over evolutionary time. Rapid phyletic pelvic reduction coupled with selective extinction of populations with vestigial pelvic structures has resulted in phylogenetic stasis.     

Body size and pelvic area relationships at puberty and two-month-pregnancy in buffalo - heifers

The relationships among body weight, height at hook bone, height at pin bone, hip width, rump length, pin width and pelvic area were estimated in puberal (n=50) and two-month pregnant (n=35) Murrah buffalo-heifers. In both types, significant correlations (P angle0.10) existed among all measurements studied. Averages for pelvic area at puberty and two-month pregnancy were 285.05 and 302.00 sq. cm, respectively. At the time of parturition, no buffalo heifer exhibited dystocia due to narrow pelvic opening.     

The bumblebee Bombus ardens ardens (Hymenoptera: Apidae) visits white clover in orchards before Oriental persimmon blooms

Flowers on the ground of orchards can provide substantial resources for wild pollinators of orchard trees. Few studies, however, have examined the relative importance of groundcover flowers to orchard pollination by analyzing pollen on the body surface of pollinators. Oriental persimmon trees bloom within the longer blooming period of white clover, which is occasionally found as a flowering plant on the ground of persimmon orchards in Japan. The present study compared the insect species assemblage collected on persimmon flowers with that on clover. Before persimmon bloomed, Bombus ardens ardens and Apis cerana japonica were the major visitors of clover flowers. Once persimmon bloomed, the former was the most abundant bee that visited persimmon flowers over the flowering period. Apis mellifera was captured only on clover flowers. We found numerous clover pollen grains on the body surface of bumblebees captured on persimmon flowers, but far fewer persimmon pollen grains on bees that visited clover. These findings show that B. ardens ardens utilized the clover flowers under the orchards before persimmon bloomed.     

Isolation of keratinophilic fungi from floor dust in Arab elementary and preparatory schools in the West Bank of Jordan

Floor dust collected from classrooms of thirty three elementary schools (16 for girls, and 17 for boys) (children aged 6–11), and twenty four preparatory schools (13 for girls, and 11 for boys) (children aged 12–14) was studied for the occurrence of keratinophilic fungi with respect to human presence and age of children. Tichophyton mentagrophytes was present in 15.4% of the preparatory schools for girls, in 12.5% of elementary schools for girls, and in 11.8% of elementary schools for boys. It was not found in preparatory schools for boys. Microsporum gypseum was found in preparatory schools for girls only (7.7%). Trichophyton terrestre was also only isolated from elementary schools for boys (5.9%). Chrysosporium species were present in 30.3% of all elementary schools (10 schools/33), and in 20.8% of all preparatory schools (5 schools/24). Geotrichum candidum was the most frequent and predominant keratinophilic species in all schools. Pathogenic and potentially pathogenic keratinophilic fungi comprised a large proportion of all fungal isolates recovered from all schools ; they comprised 87.2 %–89.5 % of all fungal isolates in the elementary schools, and 90.4%–93.5% of all fungal isolates in preparatory schools.     

Early trajectories of forest understory development on reclamation sites: influence of forest floor placement and a cover crop

We tested whether direct placement of forest floor material (FFM: litter, fibric, humus layers and surface mineral horizons) and sowing of a cover crop (Melilotus officinalis) could facilitate the establishment of native forest understory species at a reclaimed coal mine in Alberta, Canada. FFM was salvaged at two depths (15 and 40 cm) from a recently harvested native aspen forest and immediately placed at the same depths on the reclamation site. Total richness (approximately 61 species in 96 subplots) was similar in each of 3 years post‐placement; total richness for all 3 years combined was 87 including 34 typical boreal forest understory species plus 30 other natives. The deeper treatment reduced cover of all species, native and non‐native species in year 1. In year 3, the deeper treatment still had lower cover of non‐native species but had higher cover of forest understory species in years 2 and 3. The deeper treatment also resulted in lower species richness per plot, but only in year 1. In year 2 (when the biennial clover was at its tall stage), the cover crop treatment was associated with lower cover of non‐native species but did not affect the cover of native forest understory species. Direct placement of FFM can help facilitate establishment of a diverse native boreal forest understory in a reclaimed landscape. Although richness and cover may be initially higher with shallower salvage and placement, deeper salvage may ultimately be better for encouraging establishment of native forest understory species.     

大鼠产后压力性尿失禁模型的建立与探讨

目的 应用在大鼠阴道内放置水囊模拟产伤破坏大鼠盆底组织的方法建立产后压力性尿失禁( postpartum urinary incontinence,PPUI)的动物模型,并对此模型进行初步研究.方法 对40只SD雌性大鼠进行持续8h水囊扩张阴道,随机选取PPUI模型建立成功的大鼠25只并与对照同龄大鼠5只分别于模型建立后1d、1周、2周、4周、8周进行喷嚏实验以及尿动力学测定,张力换能器测定盆底肌肉肌力强度,采用JSCC标准化对应法测定血清生化指标(LDH,CK),应用逆转录-聚合酶链反应检测caspase-3基因表达,胆碱酯酶染色法计数盆底肌肉乙酰胆碱受体数量.结果 建模后喷嚏实验阳性率明显升高,阳性率为72.5％(29/40),尿动力学检测最大膀胱容量及漏尿点压力均降低,盆底肌肉收缩力下降,血清LDH、CK水平上升,盆底耻尾肌乙酰胆碱受体数量减少,与对照组比较均差异有显著性(P＜0.05).耻尾肌组织中caspase-3基因表达在建立模型当日达到最高,与对照组差异有显著性(P＜0.05),之后逐渐下降.结论 大鼠阴道内放置8h水囊的方法可以成功模拟产后压力性尿失禁,引起尿动力以及盆底肌肉的相关损伤指标发生改变.     

Anatomical evidence for glutamatergic transmission in primary sensory neurons and onto postganglionic neurons controlling penile erection in rats: an ultrastructural study with neuronal tracing and immunocytochemistry

In male rats, the dorsal penile nerve (DPN) conveys sensory information from the genitals to the lumbosacral spinal segments of the spinal cord. DPN is the afferent limb of a reflex loop that supports reflexive erections, and that includes a network of spinal interneurons and autonomic and somatic motoneurons to the penis and perineal striated muscles. Autonomic efferent pathways to the penis relay in the major pelvic ganglion (MPG). Glutamate (Glu) is a likely candidate as a neurotransmitter of reflexive erections. Both AMPA and NMDA glutamatergic receptor subunits are present in the lumbosacral spinal cord, and AMPA and NMDA receptor antagonists block reflexive erections. In the present study, we used tract-tracing experiments combined with immunohistochemical and immunocytochemical techniques to ascertain the presence of Glu at two different levels of the network controlling reflexive erections. DPN afferents were localized in the dorsal horn of the lumbosacral cord and displayed the characteristics of either C-fibers or Aδ fibers. DPN terminals (some of them glutamatergic) were mainly distributed in the medial edge of the dorsal horn in the L6 spinal segment. GluR1 subunits were present in some DPN afferents, suggesting that they could be autoreceptors. DPN fibers were also present in the MPG, as were Glu terminals and GluR4 subunits. The results reveal the presence of Glu in DPN fibers and terminals and suggest that both the spinal cord and the MPG use glutamatergic transmission to control reflexive erections. This work was supported by grant no. 5R01MH059811–03 from the NIH and by an institutional grant from the Institut National de la Recherche Agronomique.     

Dynamic Material Flow Analysis for Strategic Construction and Demolition Waste Management in Beijing

Of all materials extracted from the earth's crust, the construction sector uses 50%, producing huge amounts of construction and demolition waste (CDW). In Beijing, presently 35 million metric tons per year (megatonnes/year [Mt/yr]) of CDW are generated. This amount is expected to grow significantly when the first round of mass buildings erected in the 1990s starts to be demolished. In this study, a dynamic material flow analysis (MFA) is conducted for Beijing's urban housing system, with the demand for the stock of housing floor area taken as the driver. The subsequent effects on construction and demolition flows of housing floor area and the concurrent consumption and waste streams of concrete are investigated for Beijing from 1949 and projected through 2050. The per capita floor area (PCFA) is a key factor shaping the material stock of housing. Observations in Beijing, the Netherlands, and Norway indicate that PCFA has a strong correlation with the local gross domestic product (GDP). The lifetime of dwellings is one of the most important variables influencing future CDW generation. Three scenarios, representing the current trend extension, high GDP growth, and lengthening the lifetime of dwellings, are analyzed. The simulation results show that CDW will rise, unavoidably. A higher growth rate of GDP and the consequent PCFA will worsen the situation in the distant future. Prolonging the lifetime of dwellings can postpone the arrival of the peak CDW. From a systematic view, recycling is highly recommended for long‐term sustainable CDW management.     

Increased 5-HT3-mediated signalling in pelvic afferent neurons from mice deficient in P2X2 and/or P2X3 receptor subunits

Extracellular ATP and 5-hydroxytryptamine (5-HT) are both involved in visceral sensory pathways by interacting with P2X and 5-HT₃ receptors, respectively. We have investigated the changes in P2X and 5-HT₃-mediated signalling in pelvic afferent neurons in mice deficient in P2X₂ and/or P2X₃ subunits by whole-cell recording of L₆–S₂ dorsal root ganglion (DRG) neurons and by multi-unit recording of pelvic afferents of the colorectum. In wildtype DRG neurons, ATP evoked transient, sustained or mixed (biphasic) inward currents. Transient currents were absent in P2X₃ ^−/− neurons, whereas sustained currents were absent in P2X₂ ^−/− DRG neurons. Neither transient nor sustained currents were observed following application of ATP or α,β-methylene ATP (α,β-meATP) in P2X₂/P2X₃ ^Dbl−/− DRG neurons. 5-HT was found to induce a fast inward current in 63% of DRG neurons from wildtype mice, which was blocked by tropisetron, a 5-HT₃ receptor antagonist. The percentage of DRG neurons responding to 5-HT was significantly increased in P2X ₂ ^−/−, P2X₃ ^−/− and P2X₂/P2X₃ ^Dbl−/− mice, and the amplitude of 5-HT response was significantly increased in P2X₂/P2X₃ ^Dbl−/− mice. The pelvic afferent response to colorectal distension was attenuated in P2X₂/P2X₃ ^Dbl−/− mice, but the response to serosal application of 5-HT was enhanced. Furthermore, tropisetron resulted in a greater reduction in pelvic afferent responses to colorectal distension in the P2X₂/P2X₃ ^Dbl−/− preparations. These data suggest that P2X receptors containing the P2X₂ and/or P2X₃ subunits mediate purinergic activation of colorectal afferents and that 5-HT signalling in pelvic afferent neurons is up-regulated in mice lacking P2X₂ or P2X₃ receptor genes. This effect is more pronounced when both subunits are absent.     

Fire Severity and Long-term Ecosystem Biomass Dynamics in Coniferous Boreal Forests of Eastern Canada

The objective of this study was to characterize the effects of soil burn severity and initial tree composition on long-term forest floor dynamics and ecosystem biomass partitioning within the Picea mariana [Mill.] BSP-feathermoss bioclimatic domain of northwestern Quebec. Changes in forest floor organic matter and ecosystem biomass partitioning were evaluated along a 2,355-year chronosequence of extant stands. Dendroecological and paleoecological methods were used to determine the time since the last fire, the soil burn severity of the last fire (high vs. low severity), and the post-fire tree composition of each stand (P. mariana vs. Pinus banksiana Lamb). In this paper, soil burn severity refers to the thickness of the organic matter layer accumulated above the mineral soil that was not burned by the last fire. In stands originating from high severity fires, the post-fire dominance by Pinus banksiana or P. mariana had little effect on the change in forest floor thickness and tree biomass. In contrast, stands established after low severity fires accumulated during the first century after fire 73% thicker forest floors and produced 50% less tree biomass than stands established after high severity fires. Standing tree biomass increased until approximately 100 years after high severity fires, and then decreased at a logarithmic rate in the millennial absence of fire. Forest floor thickness also showed a rapid initial accumulation rate, and continued to increase in the millennial absence of fire at a much slower rate. However, because forest floor density increased through time, the overall rate of increase in forest floor biomass (58 g m⁻² y⁻¹) remained constant for numerous centuries after fire (700 years). Although young stands (< 200 years) have more than 60% of ecosystem biomass locked-up in living biomass, older stands (> 200 years) sequester the majority (> 80%) of it in their forest floor. The results from this study illustrate that, under similar edaphic conditions, a single gradient related to time since disturbance is insufficient to account for the full spectrum of ecosystem biomass dynamics occurring in eastern boreal forests and highlights the importance of considering soil burn severity. Although fire severity induces diverging ecosystem biomass dynamics in the short term, the extended absence of fire brings about a convergence in terms of ecosystem biomass accumulation and partitioning.