Fine structure of a murine mammary carcinoma cell line

Summary A fine structural study was made of cells from the epithelioid MCF-8/5-2A cell line derived from a MuMTV-free, D2 transplantable hyperplastic outgrowth. Electron microscopy shows the cells to be truly epithelial with many cell-to-cell junctions and microvilli. The cells are similar in many respects to normal mouse mammary gland and some of the conventional mammary tumor derived cell lines. This study supports previous observations of the absence of MuMTV in MCF-8 within the limits of morphological detection, and demonstrates the presence of numerous virus particles within, or budding into, cisternae of the endoplasmic reticulum and nuclear envelope. These intracisternal A particles have not been previously described in such abundance in mammary tumor tissue culture cells. This study was supported by Contract NIH-NCI-E-71-2421, with the NIH and by an institutional grant to the Michigan Cancer Foundation from the United Foundation of Detroit, Michigan.     

Isolation and characterization of a basic encephalitogenic protein from the central nervous system of sheep.

A basic protein has been purified from sheep brain. The purified protein sedimented in the analytical centrifuge at 56,000 r.p.m. as an homogenous product. This protein induced an allergic encephalitis when injected into guinea pigs. Some physiochemical properties of the protein were studied: the sedimentation coefficient was 1.52 and the molecular weight was 20,000 +/- 2,000, as estimated by electrophoresis in acrylamide gels containing SDS and urea; the specific extinction coefficient (see article) was 6.01 +/- 0.20. The aminoacid composition of the molecule was determined and its most prominent aspects are a high content of arginine and lysine, the presence of a single tryptophan, the total absence of cysteine and cystine and a blocked N-terminal residue. All these properties are very close to those of human and bovine encephalitogenic proteins.     

Observations on the role of simuliids and culicids in the transmission of avian and anuran trypanosomes

Although Trypanosoma rotatorium undergoes transformation and prolific multiplication in the mid and hindgut of Culex territans, several attempts to experimentally infect laboratory-reared, Rana pipiens by different routes were unsuccessful. Trypanosoma avium undergoes a similar pattern of development in the gut of Simulium rugglesi. Experimental infections of T. avium in ducklings indicates that S. rugglesi serves as an intermediate host and probably as an active and passive vector of the parasite in nature.     

Phocanema decipiens: Molting in seals

Infective larvae of the anisakine nematode Phocanema decipiens from the muscle of Atlantic cod (Gadus morhua) were fed to harbor seals (Phoca vitulina) and gray seals (Halichoerus grypus). During maturation in the stomach of seal hosts, P. decipiens molted twice; these molts are the third and fourth of its life cycle. The third molt occurred between the second and fifth days of infection. The third stage, i.e., infective larva entering the third molt, had a cuticular tooth ventral to the mouth; the fourth stage larva emerging from the third molt had three bilobed lips with dentigerous ridges. The fourth molt occurred between the 5th and 15th days in seals. A female nematode emerging from the fourth molt possesses a vulva and a vagina; a male possesses caudal alae, pre- and postanal papillae. Significant morphometric changes in nematodes were associated with both molts. Females and males of P. decipiens reached maturity after 15 to 25 days in seals. Ova were detected in the feces of the seal hosts as early as the 16th day.     

夜间变暖提高荫香叶片的光合能力

研究了不同氮供应的条件下夜间变暖对荫香叶片光合能力的影响。当植株生长在相同的日间温度(25℃),而夜间温度从18℃增至20℃时,叶片的光合速率增高(p<0.05)。高氮供应的植株,夜间变暖下其叶片光合速率较低氮供应的高,氮供应增高能促进夜间变暖提高叶片光合速率的效应。在低氮供给和夜间变暖下,植株叶片的光下呼吸和暗呼吸的增高显著(p<0.05)。无论在高氮或低氮供应下,生长在夜间变暖下的植物,其叶片的R ub isco最大羧化速率(Vcm ax)和光合电子传递最大速率(Jm ax)增高(p<0.05),氮供应能增强夜间变暖对Vcm ax和Jm ax的正向效应。夜间变暖降低植株叶片的比叶重,而增加单位叶干重的氮含量(Nm),单位叶面积的氮含量(Na)没发生明显变化。随着全球气候变化,夜间趋暖将有利于树木叶片光合能力的提高,结合高氮供给将会明显地增高植物的碳固定。     

LED照射对溃疡性结肠炎大鼠结肠粘膜组织的修复作用

研究发光二极管（1ight-emittingdiode,Um）直肠内照射对大鼠实验性溃疡性结肠炎（ulcerative colitis,UC）的抗过氧化损伤以及促进结肠粘膜组织的修复作用。34只大鼠随机分成3组：正常对照组10只、病理模型组12只与病理模型＋LED照射治疗组12只．研究中采用乙酸局部刺激复制大鼠UC模型,其中LED治疗组应用LED结肠内照射,1日1次,共10d。其后观察各组的病理变化,血清过氧化损伤水平。结果显示,LED结肠内照射能够促使实验性溃疡性结肠炎的组织修复;显著降低溃疡性结肠炎大鼠血清MDA水平、升高SOD活性。实验表明LED结肠内照射实验性溃疡性结肠炎大鼠具有抗过氧化损伤作用以及促进结肠粘膜组织的修复作用。     

Ecological speciation without host plant specialization; possible origins of a recently described cryptic Papilio species

North American Papilio canadensis and P. glaucus (Lepidoptera: Papilionidae, these Papilio = Pterourus) have previously been described as having allopatric distributions separated by a narrow hybrid zone running from Minnesota to southern New England, and southward in the Appalachian Mountains (possibly to northern Georgia). Recent patterns of hybridization and introgression suggest a more complex interaction between the two, possibly even resulting in the formation of a new species (Pterourus appalachiensis Pavulaan & Wright, 2002). Recently, extensive northward interspecific introgression of P. glaucus‐diagnostic traits has been observed in the hybrid zone. These include wing bands and other color patterns, the ability to feed on tulip tree leaves, and Hk‐100 allozymes; all are autosomally encoded. However, there has been little northward introgression of certain other P. glaucus traits (such as facultative diapause and bivoltinism, and Ldh‐100 allozymes, both X‐linked; and the Y‐linked melanic mimicry gene in females). Interspecific recombination of the X‐chromosome has evidently occurred, as shown by discordant patterns of X‐linked markers. The P. glaucus X‐linked Pgd‐100 and Pgd‐50 alleles have introgressed 200–400 km north of the historical hybrid zone, yet the P. glaucus X‐linked Ldh‐100 allele has not. The allele frequency shift for both genes is more closely related to the ‘thermal landscape’ (i.e., accumulated degree‐days above a developmental base threshold of 50 °F (=10 °C)) than to latitude. Delayed post‐diapause eclosion of cohorts within the hybrid zone, e.g., the New York/Vermont border area, has produced a natural ‘false‐second generation’ flight (a hybrid swarm of synchronous males and females, where 2300–2700 °F degree‐days have accumulated each year since 1998) that is reproductively isolated from flights of both parental species. Moreover, the newly described P. appalachiensis exhibits a unique combination of traits. These include obligate diapause, a univoltine habit, and the Ldh‐80 or Ldh‐40 alleles (as for P. canadensis), the Pgd‐100 or Pgd‐50 alleles (as for P. glaucus), and a delayed ‘false‐second generation’ reproductive flight period (as observed in the hybrid zone). Since 2001, a rare allele or ‘hybrizyme’ (Ldh‐20) has appeared in this false second generation at high frequencies (40–50%). We hypothesize that strong selection against the facultative diapause (od‐)trait (and the linked Ldh‐100 allele) in regions with 2800 °F degree‐days or less, and divergent selection in favor of Pgd‐100 (or a closely linked trait) combined with allochronic reproductive isolation, has resulted in recombinational, parapatric, hybrid speciation. There is no evidence at present that host‐plant shifts or changes in sex pheromones have driven this process, in contrast to many other speciation events in the Lepidoptera.     

The influence of marking upon bee behaviour in circle tube experiments with a methodological comparison among studies

Summary. Circle tubes were used to investigate the influence of marking upon the behavioural profiles of two halictid species; one, Penapis toroi Rozen, putatively solitary, the other, Corynura chloris (Spinola) thought to be semisocial. Previous studies have shown that solitary bees tend to exhibit avoidance behaviour and those with a reproductive division of labour tend to behave aggressively within circle tube arenas. Marked pairs of C. chloris were significantly more cooperative than unmarked pairs and marked P. toroi showed significantly increased aggression and decreased cooperation. These findings suggest that marking bees may reduce behavioural differences among taxa with different types of social organization. Recommendations are made on how to use the circle tube apparatus to detect bee populations that might be worth more detailed studies of social organization and also for standardization in the way results of these studies are presented. Further experiments are suggested to clarify the effects of certain variables upon bee behaviour using this apparatus. The data presented here are the first for any member of the subfamily Rophitinae and the first for any bee thought to be primarily semisocial. A narrower range of behaviours were observed in the Rophitine, Penapis toroi Rozen, in comparison to species from other subfamilies of Halictidae and Corynura chloris Spinola had a behavioural profile similar to that of eusocial species.Received 15 December 2003; revised 12 September 2004; accepted 15 October 2004.     

Uncertainty Analysis in Life Cycle Assessment (LCA): Case Study on Plant-Protection Products and Implications for Decision Making (9 pp + 3 pp)

Goal, Scope, and Background Uncertainty analysis in LCA is important for sound decision support. Nevertheless, the actual influence of uncertainty on decision making in specific LCA case-studies has only been little studied so far. Therefore, we assessed the uncertainty in an LCA comparing two plant-protection products.Methods Uncertainty and variability in LCI flows and characterization factors (CML-baseline method) were expressed as generic uncertainty factors and subsequently propagated into impact scores using Monte-Carlo simulation. Uncertainty in assumptions on production efficiency for chemicals, which is of specific interest for the case study, was depicted by scenarios. Results and Discussion Impact scores concerning acidification, eutrophication, and global warming display relatively small dispersions. Differences in median impact scores of a factor of 1.6 were sufficient in the case study for a significant distinction of the products. Results of toxicity impact-categories show large dispersions due to uncertainty in characterization factors and in the composition of sum parameters. Therefore, none of the two products was found to be significantly environmentally preferable to the other. Considering the case study results and inherent characteristics of the impact categories, a tentative rule of thumb is put forward that quantifies differences in impact scores necessary to obtain significant results in product comparisons.Conclusion Published LCA case-studies may have overestimated the significance of results. It is therefore advisable to routinely carry out quantitative uncertainty analyses in LCA. If this is not feasible, for example due to time restrictions, the rule of thumb proposed here may be helpful to evaluate the significance of results for the impact categories of global warming, acidification, eutrophication, and photooxidant creation.