Preliminary assessment of protein associated with airborne particles in Mexico City

The protein associated with airborne particles was measured during 1991 as an indicator of airborne biological material in different outdoor urban environments. Fifty air samples were collected simultaneously at three sampling sites, located in the north, south and downtown Mexico City, using a PM10 high-volume sampler (particles<10 μm). The air filters were weighed and protein extracted using a phosphate buffer. Protein concentrations were determined by Lowry assay. The extracts were also analysed by SDS electrophoresis and IEF using a Phastsystem. High concentrations of airborne particles were recorded at the sampling sites with a geometric mean of 70.2 μg/m³ in the south (residential area), 95.5 μg/m³ in the center (urban-commercial area), and with the highest value of 108.9 μg/m³ in the north (urban-industrial area). No statistically significant difference (P>0.05) was observed among the protein concentrations from the sampling sites and the concentrations ranged from non-detectable to 2.54 μg/m³. However, the protein concentrations presented significant difference (P<0.05) with respect to rainy and dry seasons. The Spearman correlation coefficient between protein concentration and airborne particles concentration was statistically significant (r=0.50). The molecular weights (MW) and isoelectric points (pI) for the proteins present in some of the extracts were determined. The values ranged from approximately 8000 to 106 000 Da and the pI values from nearly 4.0 to 5.85. This is important because the major allergens from inhalants are mostly acidic proteins with molecular weights in the range of 20 000–40 000 Da.     

内蒙古镶黄旗草地蝗虫潜在发生可能性评价

以内蒙古草地蝗虫产卵期、越冬期和孵化期的关键气象影响因子作为草地蝗虫气象适宜度指数构建的主要因子,对内蒙古镶黄旗2010年草地蝗虫潜在发生的气象适宜性进行评价;根据当年7月上中旬在镶黄旗的实地调查资料,选取海拔、坡向、土壤类型、土壤含砂量、植被类型、植被盖度、土地覆被类型7个相对稳定的生境因子,用模糊评判方法和3S（GIS、RS、GPS）技术对该旗草地蝗虫潜在发生的生境适宜性进行评价;最后通过构建气象-生境适宜性综合评价模型,得到该旗2010年草地蝗虫潜在发生可能性（POG）等级,并用2010年实测数据和2001-2010年历史数据对模型模拟的蝗虫发生位置和蝗灾发生面积进行验证.结果表明：用本文所建气象-生境适宜性综合评价模型对镶黄旗POG等级的评价结果是可靠的.该旗草地蝗虫潜在发生的气象适宜性等级非常一致,绝大多数为适宜等级;蝗虫潜在发生源地的空间异质性主要与生境因子有关,在海拔1300～1400 m的平地/东坡/南坡、植被盖度30%～50%的温带丛生禾草草原、土壤含砂量60%～80%的典型栗钙土的生境条件下,草地蝗虫潜在发生的可能性最高.     

Interspecific gene flow in a multispecies oak hybrid zone in the Sierra Tarahumara of Mexico

Background and Aims

Interspecific gene flow can occur in many combinations among species within the genus Quercus, but simultaneous hybridization among more than two species has been rarely analysed. The present study addresses the genetic structure and morphological variation in a triple hybrid zone formed by Q. hypoleucoides, Q. scytophylla and Q. sideroxyla in north-western Mexico.

Methods

A total of 247 trees from ten reference and 13 presumed intermediate populations were characterized using leaf shape variation and geometric morphometrics, and seven nuclear microsatellites as genetic markers. Discriminant function analysis was performed for leaf shape variation, and estimates of genetic diversity and structure, and individual Bayesian genetic assignments were obtained.

Key Results

Reference populations formed three completely distinct groups according to discriminant function analysis based on the morphological data, and showed low, but significant, genetic differentiation. Populations from the zone of contact contained individuals morphologically intermediate between pairs of species in different combinations, or even among the three species. The Bayesian admixture analysis found that three main genetic clusters best fitted the data, with good correspondence of reference populations of each species to one of the genetic clusters, but various degrees of admixture evidenced in populations from the contact area.

Conclusions

The three oak species have formed a complex hybrid zone that is geographically structured as a mosaic, and comprising a wide range of genotypes, including hybrids between different species pairs, backcrosses and probable triple hybrids.     

Evaluating hypotheses on the origin and diversification of the ringneck snake Diadophis punctatus (Colubridae: Dipsadinae)

Close affinities recognized between taxa in Mexico and the contiguous USA have led to a variety of biogeographical scenarios. One such hypothesis suggests that species that occur in both countries have an origin in central Mexico followed by dispersal into the USA. This study expands upon previous phylogeographical work of the ringneck snake Diadophis punctatus by incorporating new data from previously unsampled areas appropriate to critically assess hypotheses regarding a Mexican origin for this species. Maximum likelihood and maximum parsimony analyses inferred a derived position for the lineage from southern Mexico with constraint tests for alternate evolutionary hypotheses resulting in significantly worse likelihood values. Ancestral area reconstructions inferred an origin for D. punctatus in the south‐eastern USA followed by a south‐east to north‐east then westward directionality of historical migration. The position within the phylogeny and date estimate for the south‐western + Mexico clade suggests a recent invasion into central Mexico with expansion into the Nearctic/Neotropic transition zone. The extensive lineage diversity inferred from the mtDNA suggests that the genus is a complex of cryptic species whose conservational status should be re‐evaluated on both the national and regional levels. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 629–640.     

Characterization of tidal pool algae in the Mexican Tropical Pacific coast

Tidal pools in the Mexican Tropical Pacific coast have received relatively little attention in spite of their considerable richness in species and wide distribution in the region.This paper presents the first characterization of the algal flora of this region. It analyzes the number and composition of species of the tidal pools of six localities with regard to geographical distribution and its seasonal variations as well as tidal level. 97 species are reported, 25 Chlorophyta, 23 Phaeophyta, 34 Rhodophyta and 15 Cyanophyta.Of that total of species, 63% were found in one locality, 23.7% in two, 11.3% in three and 1 % in 4 or 5 localities. Not one species was common to all of the pools.The highest number of species was found on pools of the middle and low intertidal where the Chlorophyta, Rhodophyta and Phaeophyta were the most abundant algae. Cyanophyta was more common in the supralittoral and high intertidal pools.     

Applying the Ocean Health Index framework to the city level: A case study of Xiamen,China

The Ocean Health Index (OHI), which provides a new insight into the assessment of ocean ecosystems, has attracted wide attention recently since it was proposed in 2012. It has been applied to assess the oceans at the global, national and regional levels. However, the application of the OHI framework at the city level has not been reported yet. In this study, the feasibility of applying the OHI framework to assess the health status of the oceans at the city level was explored by a case study in Xiamen of China (Xiamen OHI). Xiamen OHI aims at assessing the current status of ocean health in the Xiamen City, but not comparing to other regional or international OHI cases. Large adjustments including setting goals, parameters and reference points were undertaken to customize the OHI framework to the city scale in Xiamen. The results showed the overall score for Xiamen OHI was 52 out of 100, ranging from 28 to 96 across different goals. Goals related to ecological factors including Clean Waters, Coastal Storage, Coastal Protection received very low scores; on the contrary, goals related to social and economic factors including Tourism and Recreation, Sense of Place and Coastal Livelihoods and Economies were scored high. The case study of Xiamen OHI indicates the feasibility of the application of the OHI framework at the city level after necessary adjustments, and the results can also direct to effective ocean health improvement in the future. This study thus contributes to promote the application of OHI framework at the local levels.     

Riparian plant species differ in sensitivity to both the mean and variance in groundwater stores

确定气候的长期缓慢变化与放大的气候变异性之间相互作用的生态后果是植物生态学的一个重要前沿研究。我们将最近的气候敏感性函数方法与修订的水文“水桶模型”相结合，以改进对植物物种如何响应地下水资源平均值和方差变化的预测。利用河岸植被覆盖和地下水位长期数据集的时空变化，构建了旱地河岸廊道常见植物种类的首个地下水敏感性函数。我们的研究结果展示了这种方法的重要性，它可以识别在日益变化的气候层，随着地下水储量的下降，哪些植物物种能够繁茂的生长(或衰落)。研究结果表明，河岸带植物物种对地下水位平均值和方差的敏感性各不相同。杨树(Populus deltoides ssp. wislizenii)随着地下水年际方差的增大，植被覆盖度预计将下降，而狼柳树 (Salix exigua)和其他原生湿地物种预计将受益于更大的年际方差。非本地物种对地下水变化不敏感，但俄罗斯橄榄(Elaeagnus angustifolia)在更深的平均地下水位条件下敏感性将降低。暖空气温度调节了杨树对地下水的敏感性，在最高温度更高的年份/地点，杨树对地下水的变化比在低温地点/时期更敏感。地下水年内变异系数越大，杨树覆盖度下降幅度越大，但与年际变异系数相关性不显著，这可能因为相对于杨树的寿命，这个时间(16 a)太短。与此相反，非本地柳树(Tamarix chinensis)覆盖度随地下水年内和年际变异系数的增加而增加。总之，我们的研究结果预测，地下水变异性和平均值的变化将通过单个植物物种对地下水储量中的平均值和方差的不同敏感性影响河岸带植物群落。     

Soluble suppressor factors elaborated in experimental malignant ascites

Soluble suppressor factors in the sera of cancer patients inhibit lectin-stimulated lymphocyte proliferation. These factors, derived from human material, preclude easy corroboration by other investigators. To gain a general understanding of soluble suppressor factors and to avoid the necessary restrictions of human experimentation, an animal model was devised. Sprague-Dawley rats were injected ip with the Walker 256 carcinoma. The resultant ascites proved to be a stable, reproducible source of soluble suppressor factors. Ascites inhibited phytohemagglutinin (PHA)-induced blastogenesis of normal splenocytes by 98%. The possibility of a toxic effect was eliminated by vital staining of splenocytes and by examination in a specific lymphotoxin assay. Suppressor activity persisted after heating at 100 °C for 40 min. Extraction by lipid solvents revealed that the bulk of suppressor activity resides in the lipid phase. The active fraction of heat-treated ascites passed through an Amicon PM-10 filter. Thin-layer chromatography revealed the presence of prostaglandins E₂ and F_2a. Tissue culture supernatants from short-term cultures derived from tumor-bearing animals revealed suppressor activity from thymus, spleen, and liver cultures (97, 91, and 71%, respectively). No suppressor activity was detected in cultures of cancer cells. This study has demonstrated in this animal model that prostaglandins play a major role in suppression of lectin-induced blastogenesis. All suppressor factors appear to be host derived. An understanding of the mechanism of release of these suppressor substances may open new avenues in the immunotherapy of cancer.     

Conversion of diglyceride to triglyceride by rat liver microsomes: a requirement for the 105,000 x g supernatant

This paper describes a requirement for the 105,000 × g supernatant of rat liver for the synthesis of triglyceride from diglyceride and palmityl coenzyme A by rat liver microsomes. ATP and magnesium chloride are also required. The incorporation of both [1-¹⁴C]-palmityl coenzyme A and [1-¹⁴C]-diolein into triglyceride has been observed. The 105,000 × g supernatant has no enzymatic activity for this reaction when incubated in the absence of microsomes. The supernatant contains a soluble, essential protein which is nondialyzable, heat sensitive, and destroyed by trypsin. Net synthesis of triglyceride has been demonstrated by chemical analysis.     

Secular trend for stature in adult male Yucatec Maya to 1968

Statures for 64 adult male Yucatec Maya (18+ years old, sons of campesinos) were measured in 1968 and compared with mean statures presented in results for previous studies. There were no significant changes in mean stature since 1895. If the sample is divided into 5-year age groups, no secular trend is evident. Using osteological information from as early as the Late Preclassic, stature of adult Maya males has decreased 119 mm in a little more than 20 centuries (?0.06 cm/decade). Comparing the results with measurements from other Mesoamerican groups, only one – the Otomí – show evidence of significant secular change. It is possible that modern economic development schemes in Mesoamerica are too recent or ineffective to have had an effect on stature.