Preservation of tube feet in an ophiuroid (Echinodermata) from the Lower Devonian Hunsrück Slate of Germany and a redescription of<Emphasis Type="Italic">Bundenbachia beneckei</Emphasis> and<Emphasis Type="Italic">Palaeophiomyxa grandis</Emphasis>

The preservation of non-mineralized tissues in the fossil record is extremely rare. The Lower Devonian Hunsrück Slate of Germany has long been known for the preservation of non-mineralized tissues in pyrite but whether or not these remnants represent true soft tissues has been questioned. This is especially true for struetures visible only on radiographs that are too delicate for excavation by traditional methods. Here we report the discovery of well-preserved pyritized tube feet in six fully prepared specimens of the protasterid brittle starBundenbachia beneckei from the Hunsrück Slate. This discovery represents the first report of fossilized ophiuroid tube feet in the fossil record. The successful excavation of the delicate tube feet was made possible by improved airbrasive techniques developed by German fossil collectors. The relatively large size of the fossil tube feet inBunden-bachia beneckei is consistent with earlier inferences on size based on the presence of large podial basins. Protasterid ophiuroids lack the specialized arm musculature and articulations that provide increased flexibility and strength to the arms of modern ophiuroids with typically reduced tube feet. How-ever, tube foot form and perhaps function inBundenbachia might have been similar to those of living asteroids in which large tube feet are used primarily for locomotion and food-manipulation thus compensating for a lack of specialized arm musculature and articulation. Hence, feeding and life mode of protasterid ophiuroids was not necessarily limited to sedentary, infaunal microphagy as traditionally suggested. Two Hunsrück protasterid ophiuroids,Bundenbachia benecki andPalaeophiomyxa grandis are redescribed and compared.      

Kinetic behaviour of α-galactosidase produced by Absidia griseola: a comparison between free and immobilized forms of the enzyme

In this research the characteristics of free (partially purified) and immobilized (mould pellets of Absidia griseola) -galactosidase have been investigated. Inhibition studies of the enzyme showed that p-nitrophenol and sucrose do not have any inhibitory effect on the enzyme, but that galactose is a competitive inhibitor. In the immobilized form, inhibition was lower than in the free enzyme and the level of inhibition decreased as the temperature increased. The activity and stability of free and immobilized enzyme were investigated with respect to temperature, and the results showed that the optimal temperature range of the free enzyme was 45–50 °C, while the immobilized enzyme had an optimum at 55–60 °C. The optimum pH for the free enzyme was 6.0 and the value was decreased to 5.0 by immobilizing. The experimental effectiveness factors were found to be represented as a single function of the modified Thiele modulus, including parameters such as pellet size, enzyme concentration in the pellets and substrate concentration. Both experimental and theoretical data concerning effectiveness factors are nearly the same.     

Morphological Studies of Rhaphidopteris hsüi sp. nov

The present paper deals with the cuticular structure of Rhaphidopteris hsüi sp. nov. The specimens were collected from the Upper Triassic cos series of Liuzhi district, Guizhou Province. Based on the shape and cuticular structure of leaf and segments, this new species is assigned to Corystospermaceae of Cycadofilicales. According to the assemblage of the fossil plants, the writers consider that the geological age of this flora is assigned to the middle Keuper-Rhaetic stage of Late Triassic.     

长江上游圆筒吻(鱼句)年龄与生长的研究

于2008—2010年在长江上游四川合江和重庆木洞江段共采集圆筒吻鮈样本511尾,研究了其年龄与生长特征,并提出了合理的鱼类资源保护对策。结果表明,所采集的圆筒吻鮈分6个年龄组,2—4龄居多,占95.7%;体长与鳞径为直线正相关,雌雄群体间无显著差异,表达式为L=51.28 R+37.45(r=0.85,n=397);各龄组、雌雄群体的实测体长均值和退算体长均值无明显差异(t=0.751,P>0.05);体长与体重呈幂函数关系,雌雄群体间无显著差异,表达式为W=8×10 6L3.099(r=0.97,n=397),其生长属等速增长类型;生长规律可以用von Bertalanffy方程表示,分别为:Lt=348.78[1 e 0.18(t+1.15)],Wt=603.17[1 e 0.18(t+1.15)]3.099;生长拐点处的年龄为5.12,此时的体长和体重分别为236.23 mm和180.33 g;圆筒吻鮈个体出现小型化现象;根据研究,长江上游圆筒吻鮈处于不合理的开发状态,应限制捕捞、加强保护。     

Model for the three-dimensional structure of vitronectin: predictions for the multi-domain protein from threading and docking.

The structure of vitronectin, an adhesive protein that circulates in high concentrations in human plasma, was predicted through a combination of computational methods and experimental approaches. Fold recognition and sequence-structure alignment were performed using the threading program PROSPECT for each of three structural domains, i.e., the N-terminal somatomedin B domain (residues 1-53), the central region that folds into a four-bladed beta-propeller domain (residues 131-342), and the C-terminal heparin-binding domain (residues 347-459). The atomic structure of each domain was generated using MODELLER, based on the alignment obtained from threading. Docking experiments between the central and C-terminal domains were conducted using the program GRAMM, with limits on the degrees of freedom from a known inter-domain disulfide bridge. The docked structure has a large inter-domain contact surface and defines a putative heparin-binding groove at the inter-domain interface. We also docked heparin together with the combined structure of the central and C-terminal domains, using GRAMM. The predictions from the threading and docking experiments are consistent with experimental data on purified plasma vitronectin pertaining to protease sensitivity, ligand-binding sites, and buried cysteines.     

A note on plating efficiency in fluctuation experiments

In estimating mutation rates using the Luria-Delbrück experimental protocol, it is often assumed that all mutant cells survive the plating procedure to form visible mutant colonies. This assumption of perfect plating efficiency may not hold in certain circumstances, but none of the existing estimation methods that adjust for plating efficiency is strictly based on the likelihood principle. To ameliorate this situation, we propose likelihood based algorithms for computing point and interval estimates of mutation rates.     

A NEW SPECIES OF BRITTLESTAR (OPHIUROIDEA, ECHINODERMATA) FROM THE HUNSRÜCK SLATE (LOWER EMSIAN, LOWER DEVONIAN) OF GERMANY

Abstract:  Lapworthura lehmanni , a new species of ophiuroid, is described from four specimens from the Lower Devonian Hunsrück Slate of Germany. It is the only known ophiuroid in the Hunsrück Slate with paired but unfused ambulacrals, and it exhibits unique rows of spine-bearing dorsal arm ossicles. The genus Lapworthura Gregory was previously known only from the Ordovician of Scotland and the Silurian of England and Australia.     

An ophiuroid trackway from the Lower Devonian Hunsrück Slate, Germany

A new trace fossil, Arcichnus saltatus , from the Lower Devonian Hunsrück Slate, Germany, is interpreted as the trackway of a protasterid ophiuroid, Taeniaster. The trackway consists of a series of horseshoe-shaped impressions, produced by a pair of arms, a feature characteristic of some ophiuroid trackways. This new trace fossil demonstrates that protasterids lived both infaunally and epifaunally.     

视神经损伤后视网膜Müller细胞未折叠蛋白反应相关因子IRE-1与GLAST的表达

目的：研究视神经损伤后视网膜Müller细胞中是否有未折叠蛋白反应（UPR）及其与L一谷氨酸/L一天门冬氨酸转运体（GLAST）的关系。方法：视神经钳夹伤模型建立成功后,运用HE染色观察视网膜神经节细胞数目改变,免疫化学染色,免疫荧光双标记,western-blot观察UPR相关因子需肌醇酶1（IRE-1）与GLAST的表达及相关性。结果：视神经钳夹伤后IRE-1与GLAST在视网膜Muller细胞上共表达,,术后第一天前呈上升趋势,在第一天达到顶峰,后呈下降趋势,第七天下降明显。结论：视神经损伤后,IRE-1与GLAST的趋势变化有一定相关性,提示未折叠蛋白反应可能是调控GLAST变化的原因之一。     

棉铃虫滞育与抗逆性研究进展

本文综述了棉铃虫滞育与抗逆性的研究进展 ,包括滞育的类型、滞育的诱导与解除 ,以及抗寒性、抗热性、抗旱性等。其中着重论述了棉铃虫的越冬滞育及其抗寒能力