Resolution of sensory and mucoid glycoconjugates with terminal α-galactose residues in the mucomicrovillar complex of the vomeronasal sensory epithelium by dual confocal laser scanning microscopy

The organization of the mucomicrovillar complex of the vomeronasal sensory epithelium of adult rats was examined using confocal laser scanning microscopy. In specimens labeled with the FITC-conjugated isolectin B₄ of Bandeiraea simplicifolia, which recognizes terminal -galactose sugar residues of glycoconjugates, we demonstrated that the mucomicrovillar complex was composed of islet-like structures with a high-density -galactose core. The mucomicrovillar complex was further resolved into sensory and mucoid components in double-labeling and dual scanning experiments. The sensory component, which consists of the dendritic terminals of olfactory marker protein-immunoreactive vomeronasal receptor neurons, contained cytosolic glycoconjugates with terminal -galactose sugar residues. The extracellular mucoid component consisted of glycoconjugates containing terminal -galactose derived from the glands associated with the vomeronasal organ. These results demonstrated the complex microchemical organization of the sensory and mucoid components of the mucomicrovillar complex.     

The role of Helicobacter spp. in the pathogenesis of primary biliary cirrhosis and primary sclerosing cholangitis

Helicobacter species DNA has been detected in liver tissue of patients affected by primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). To investigate a potential causative relation between Helicobacter species and PBC/PSC, we compared the presence of Helicobacter species-specific DNA in liver tissue of patients with PBC/PSC (n=18/n=13) with those of a control group of patients with various liver diseases with known cause (n=29). A PCR with Helicobacter genus-specific 16S rRNA primers was performed on DNA isolated from paraffin embedded liver tissue. Control patients had hepatitis-B (n=9), alcoholic cirrhosis (n=14), or non-cirrhotic metabolic liver disease (n=6). There was no significant difference between the incidence of Helicobacter spp.-specific DNA in PBC/PSC (9/31; 29%) and the control group (10/29; 34%). Sequence analysis confirmed Helicobacter spp. DNA. Because Helicobacter spp. DNA can be found in approximately one-third of all samples tested, it is unlikely that PSC and PBC are caused by Helicobacter infection.     

Evidence of an emerging female preference for an artificial male trait and the potential for spread via mate choice copying in Poecilia latipinna

The initial purpose of the project described herein was to assess the preference of female Poecilia latipinna for an artificial novel male trait—an orange‐colored distal fringe added to the caudal fin of an otherwise wild‐type conspecific. Analysis of the preliminary data revealed consistent individual differences in the strength of female preference for either orange‐tailed or wild‐type males. This finding inspired the study's second aim—to evaluate whether the preference for orange‐tailed males observed among a subset of females could spread via mate choice copying to others in the population that initially preferred wild‐type males. Two experiments and a control were conducted wherein females were simultaneously presented with an orange‐tailed and a wild‐type dummy male using a standard dichotomous choice design. In the first experiment, female preference was assessed on two separate occasions in order to characterize the variability and consistency in preference for orange‐tailed versus wild‐type males. The second experiment addressed mate choice copying: Female preference was again assessed on two separate occasions, but involved pairing a model female with the non‐preferred male for a period of time between preference tests. A third set of control tests were conducted using the same protocol as the copying experiment except that subject females were unable to see the model paired with the non‐preferred male. Results showed that, although females collectively preferred neither the orange‐tailed nor the wild‐type dummy male in the first round of preference tests, the majority showed relatively strong individual preferences. The subset of females that preferred the orange‐tailed over the wild‐type male in the first round of testing all maintained their preferences in the second round whether or not they had observed a model in association with the non‐preferred wild‐type male between tests. However, females that preferred the wild type over the orange male in the first round of testing copied the model's choice of the non‐preferred orange‐tailed male in their second round of preference testing. These results highlight the importance of recognizing the likelihood that only a subset of females will express a preference as it first emerges within a population. In such instances, the preference may not be detected at the population level—a point frequently overlooked in studies of mate choice. Additionally, these data highlight the importance of assessing the preferences of individual females and their capacity to drive evolutionary change within populations. Lastly, this study offers evidence of a possible mechanism by which a novel male trait might spread via mate choice copying by exploiting an emerging sensory bias within a subset of females in the population.     

Neuronal KGB-1 JNK MAPK signaling regulates the dauer developmental decision in response to environmental stress in Caenorhabditis elegans

In response to stressful growth conditions of high population density, food scarcity, and elevated temperature, young larvae of nematode Caenorhabditis elegans can enter a developmentally arrested stage called dauer that is characterized by dramatic anatomic and metabolic remodeling. Genetic analysis of dauer formation of C. elegans has served as an experimental paradigm for the identification and characterization of conserved neuroendocrine signaling pathways. Here, we report the identification and characterization of a conserved c-Jun N-terminal Kinase-like mitogen-activated protein kinase (MAPK) pathway that is required for dauer formation in response to environmental stressors. We observed that loss-of-function mutations in the MLK-1-MEK-1-KGB-1 MAPK pathway suppress dauer entry. A loss-of-function mutation in the VHP-1 MAPK phosphatase, a negative regulator of KGB-1 signaling, results in constitutive dauer formation, which is dependent on the presence of dauer pheromone but independent of diminished food levels or elevated temperatures. Our data suggest that the KGB-1 pathway acts in the sensory neurons, in parallel to established insulin and TGF-β signaling pathways, to transduce the dauer-inducing environmental cues of diminished food levels and elevated temperature.     

Biochemical measurements of beef are a good predictor of untrained consumer sensory scores across muscles

The ability of the biochemical measurements, haem iron, intramuscular fat (IMF%), moisture content, and total, soluble and insoluble collagen contents, to predict untrained consumer sensory scores both across different muscles and within the same muscle from different carcasses were investigated. Sensory scores from 540 untrained French consumers (tenderness, flavour liking, juiciness and overall liking) were obtained for six muscles; outside (m. biceps femoris), topside (m. semimembranosus), striploin (m. longissimus thoracis), rump (m. gluteus medius), oyster blade (m. infraspinatus) and tenderloin (m. psoas major) from each of 18 French and 18 Australian cattle. The four sensory scores were weighted and combined into a single score termed MQ4, which was also analysed. All sensory scores were highly correlated with each other and with MQ4. This in part reflects the fact that MQ4 is derived from the consumer scores for tenderness, juiciness, flavour and overall liking and also reflects an interrelationship between the sensory scores themselves and in turn validates the use of the MQ4 term to reflect the scope of the consumer eating experience. When evaluated across the six different muscles, all biochemical measurements, except soluble collagen, had a significant effect on all of the sensory scores and MQ4. The average magnitude of impact of IMF%, haem iron, moisture content, total and insoluble collagen contents across the four different sensory scores are 34.9, 5.1, 7.2, 36.3 and 41.3, respectively. When evaluated within the same muscle, only IMF% and moisture content had a significant effect on overall liking (5.9 and 6.2, respectively) and flavour liking (6.1 and 6.4, respectively). These results indicate that in a commercial eating quality prediction model including muscle type, only IMF% or moisture content has the capacity to add any precision. However, all tested biochemical measurements, particularly IMF% and insoluble collagen contents, are strong predictors of eating quality when muscle type is not known. This demonstrates their potential usefulness in extrapolating the sensory data derived from these six muscles to other muscles with no sensory data, but with similar biochemical parameters, and therefore reducing the amount of future sensory testing required.     

采用共聚焦显微术对家兔呼吸道感受器进行观察

呼吸道感受器在机体对肺部物理和化学环境变化作出反应时起到重要作用,它们引起的反射具有调节或保护作用,或产生病理效应。基于电生理研究,可将呼吸道感受器分为四类,但它们的组织结构不详。由于对感受器形态的认识不足,阻碍了对其生理功能的理解。近来,我们采用共聚焦显微术与免疫组织化学方法（用钠钾ATP酶作为标记),首次高清晰度地展示了呼吸感受器结构。本文采用这种新方法在家兔中进行了系统观察。结果显示,各级气道通均有多种不同的感受器结构。大气道中的结构往往比小气道中的复杂,虽然它们的大小、所在部位与走向不尽相同,但都有多个终端末梢。有些感受器埋置在气道平滑肌中,其结构便于感受对气道的机械性刺激：有些覆盖在气道上皮的表面,其形态适合于感受通过气道的刺激性物质;另一些则位于气道粘膜下,在上皮与平滑肌之间。有些传入神经轴突可支配多个感受器结构。据此,传入单纤维中记录到的电活动是来自一个感觉单位。后者可以由多个感受器组成。除了感受器之外,我们还观察到气道内神经节,它们与感受神经的轴突密切相关。本文证实气道内存在不同形态结构的感受器,并探讨了其生理分类。     

Regulation of primary spinal neuron lineages after deletion of a major progenitor

Vertebrate embryos are able to reconstitute the body plan when early blastomeres are deleted, but it is not known whether this is accomplished by cells local to the lesion or by a readjustment of the entire pattern of the embryo. We distinguished between these two possibilities by studying which embryonic cells change primary spinal neuronal fates after deletion of a major spinal cord progenitor. After ablation of the V1.2 blastomere of the 16-cell Xenopus embryo, the spinal cord contained normal numbers of Rohon-Beard neurons and primary motoneurons, indicating that the remaining blastomeres numerically reconstituted these populations. Using lineage-tracing techniques we revealed a global response: 10 out of the 15 remaining blastomeres significantly changed the number of one or both neuronal types they produced. This widespread response indicates that position in the early embryo plays an important role in regulating the production of primary spinal neurons. However, not all cells are influenced solely by position; a vegetal cell transplanted into the position of the deleted V1.2 did not take on the neuronal fate of its new position. Thus, restitution of pattern relies on a combination of positional cues and intrinsic fate restrictions.     

Mass spectrometric strategy for primary structure determination of N-terminally blocked peptides

The mass spectrometric strategy including three steps is presented for primary structure determination of the N-terminally blocked peptides. First, the C-terminal sequencing is performed by using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry coupled with carboxypeptidase Y digestion. Then, the peptide is cleaved according to the obtained C-terminal sequence information and the resulting peptides are identified by mass spectrometry and Edman degradation after fractionation by reverse-phase chromatography. Finally, the N-terminal fragment is sequenced by tandem mass spectrometry. The strategy was successfully applied to the sequence determination of two novel N-terminally blocked peptides named EAFP1 and EAFP2.