Sensitive dependence of the coefficient of variation of interspike intervals on the lower boundary of membrane potential for the leaky integrate-and-fire neuron model

After the report of Softky and Koch [Softky, W.R., Koch, C., 1993. The highly irregular firing of cortical cells is inconsistent with temporal integration of random EPSPs. J. Neurosci. 13, 334-350], leaky integrate-and-fire models have been investigated to explain high coefficient of variation (CV) of interspike intervals (ISIs) at high firing rates observed in the cortex. The purpose of this paper is to study the effect of the position of a lower boundary of membrane potential on the possible value of CV of ISIs based on the diffusional leaky integrate-and-fire models with and without reversal potentials. Our result shows that the irregularity of ISIs for the diffusional leaky integrate-and-fire neuron significantly changes by imposing a lower boundary of membrane potential, which suggests the importance of the position of the lower boundary as well as that of the firing threshold when we study the statistical properties of leaky integrate-and-fire neuron models. It is worth pointing out that the mean-CV plot of ISIs for the diffusional leaky integrate-and-fire neuron with reversal potentials shows a close similarity to the experimental result obtained in Softky and Koch [Softky, W.R., Koch, C., 1993. The highly irregular firing of cortical cells is inconsistent with temporal integration of random EPSPs. J. Neurosci. 13, 334-350].     

Some lignicolous marine fungi from Sri Lanka

Koch, J. 1982. Some lignicolous marine fungi from Sri Lanka. – Nord. J. Bot. 2 : 163–169. Copenhagen. ISSN 0107–055X.
Twenty–seven marine fungi are reported from intertidal wood collected in the Indian Ocean at Sri Lanka. One new genus Nimbospora and two new species Nimbospora effusa and Halosarpheia bentotensis are described. A new combination Savoryella paucispora is proposed. Obervations are presented on some poorly known and interesting species.     

几种中国肥蛛的修订（蜘蛛目：园蛛科）

对尹长民等1990年发表的中国肥蛛属作了必要的修订,其中新的同物异名2种,3种肥蛛雄蛛配对有误。     

Comparative Complete Chloroplast Genome Analyses and Contribution to the Understanding of Chloroplast Phylogeny and Adaptive Evolution in Subgenus Anguinum

Russian Journal of Genetics - The subgenus Anguinum (G. Don. ex W.D.J. Koch) N. Friesen disjunctly distributes in the high mountains from south-western Europe to eastern Asia and in northeastern...     

STUDIES OF THE MOTILE CELLS OF CHYTRIDS. III. MAJOR TYPES

Koch , William J. (U. North Carolina, Chapel Hill.) Studies of the motile cells of chytrids, III. Major types. Amer. Jour. Bot. 48(9): 786–788. Illus. 1961.—Six major types of chytrid motile cells are recognized on the basis of the internal parts present and their appearances and arrangements. Eighteen species are placed in these 6 types.     

A mathematical model applied to the fungal colony growth of Sclerotium rolfsii

Colonies of Sclerotium rolfsii growing on solid medium showed a linear increase in radius simultaneously with exponential changes in colonial weight. The mathematical model developed by Koch (Koch, A.L. 1975. J. Gen. Microbiol. 89, 209216) to describe similar kinetics of mycelial growth was applied. Most of the parameters defined in the mentioned model were directly measured or calculated, except the values of K (maximum mycelium carrying capacity) and S (initial mycelial density) which were fitted to the experimental data of growth at 30°C and 23°C. The ratios K/S at 30°C and at 23°C were 18.8 and 1200 respectively, being consistent with two-dimensional growth. The model was predictive only during the exponential increase of the colony weight.     

Hope for a broken heart?

Heart failure affects 23 million people worldwide and results from cardiac dysfunction characterized by decreased responsiveness to beta-adrenergic stimulation. A recent publication by W.J. Koch and colleagues highlights evidence for targeted beta-adrenergic receptor kinase (betaARK1) inhibition by gene transfer to improve contractile function and beta-adrenergic responsiveness in failing human myocardium. This proof-of-concept study has great importance for future heart failure therapy because it provides evidence for the therapeutic effectiveness of betaARK1 inhibition in failing human myocardium.     

Analysis of a circular code model

A circular code has been identified in the protein (coding) genes of both eukaryotes and prokaryotes by using a statistical method called trinucleotide frequency (TF) method [Arquès & Michel (1996). J. theor. Biol. 182, 45-58]. Recently, a probabilistic model based on the nucleotide frequencies with a hypothesis of absence of correlation between successive bases on a DNA strand, has been proposed by Koch & Lehmann [(1997). J. theor. Biol. 189, 171-174] for constructing some particular circular codes. Their interesting method which we call here nucleotide frequency (NF) method, reveals several limits for constructing the circular code observed with protein genes.     

迎春花花粉对伪钝绥螨生长发育和繁殖的影响

伪钝绥螨Amblyseius fallacis Garman是控制害螨的有效天敌,研究迎春花花粉和二斑叶螨Tetranychus urticaeKoch对伪钝绥螨生长发育和繁殖的影响,比较伪钝绥螨取食2种食料时各种参数的异同。结果表明,迎春花花粉可使伪钝绥螨正常生长发育并产卵,但发育时间较取食二斑叶螨的长,产卵量与取食二斑叶螨的相当。取食迎春花花粉时伪钝绥螨的内禀增长率、净增殖率和周限增长率均低于取食二斑叶螨时的值,世代平均周期较取食二斑叶螨略短,而种群倍增所需时间更长。由以上结果可知迎春花花粉可作为伪钝绥螨的替代或补充食料。     

Larval identification of species and subspecies of the genus Hyalomma (Acari: Ixodidae) from Russia and neighbouring territories

The following species and subspecies of Hyalomma Koch, 1844 are recorded from Russia and neighbouring territories, including those involved in natural foci of tick-borne diseases: H. (Hyalomma) aegyptium (Linnaeus, 1758), H. (Euhyalomma) dromedarii Koch, 1844, H. (Euh.) asiaticum asiaticum Schulze et Schlottke, 1930, H. (Euh.) asiaticum caucasicum Pomerantzev, 1940, H. (Euh.) asiaticum kozlovi Olenev, 1931, H. (Euh.) anatolicum Koch, 1844, H. (Euh.) excavatum Koch, 1844, H. scupense Schulze, 1918, H. (Euh.) marginatum marginatum Koch, 1844, H. (Euh.) marginatum turanicum Pomerantzev, 1946, and H. (Euh.) marginatum rufipes Koch, 1844. The geographic distribution and host-parasite relationships of each taxon are discussed. Species characters of the larval stage, that can be distinguished using light microscopy, are found to be very few. These characters include shape of scutum, shape and rate of hypostome denticulation, shape and rate of the development of spurs on coxae I to III. Measurements of some morphological structure and their rations show statistically significant differences between some closely related species, even if qualitative discriminating characters are unknown. Only measurements and their ratios can be used for the discrimination of larval H. anatolicum from larval H. excavatum, because qualitative discriminating features have not been found for these species. The complex structure of the subspecific morhological differentiation of all parasitic stages in the polymorphic species H. asiaticum and H. marginatum is revealed. This structure probably reflects some peculiarities of the microevolutionary processes. Identification key for the larval stage of seven Hyalomma species is provided.     

中国北方15种革螨的季节数量变动

作者曾在吉林省西部草原和甘肃省甘南高原调查了革螨的季节数量变动,本文报道的１５种革螨指数均为夏季最高,春,秋二季较低。     

青海鹅观草属的叶片表皮微形态特征及其分类意义的探讨

通过青海鹅观草属叶片表皮的解剖观察,结合外部形态,表明了该属植物在小麦族中共族分属的合理性,同时对青海地区属下类群重新进行了确认,共划分2组16种,即拟技碱草组,包括6种;弯穗草组,包括10种．过去处理的种短柄鹅观草和多秆鹅观革分别作为短颖鹅观草和缘毛鹅观草的变种。此外,类群间的演化水平和属的地理起源也作了初步探讨。     

On the Spiders Collected during the Swedish Expeditions to Novaya Zemlya and Yenisey in 1875 and 1876

The material collected in 1875 and determined by L. Koch has been revised. The material from 1876 has been determined and a list of 197 species from Russia, Novaya Zemlya and Siberia represented in the two collections is given and in addition 14 species collected by the 1875 expedition in Northern Norway. Hybauchenidium gen.n. of the fam. Erigonidae is established with Erigone aquilonaris L. Koch, 1879, as type species. Eboria sibirica sp.n. (Erigonidae), and Diplocephalus cristatus angustieeps subsp.n. (Erigonidae) are described. A list of the species described and recorded by L. Koch in 1879 with the actual names is given.     

The distribution of Hyalomma spp. ticks from domestic ruminants in Iran

The distribution of Hyalomma species on domestic animals was studied in four zoogeoghraphical zones. Nine hundred and ninety-two Hyalomma ticks were collected from sheep, goats, cattle and camels. A total of seven tick species consisting of: Hyalomma anatolicum Koch, 1844 (28.93%), H. excavatum Koch, 1844 (12.5%), H. asiaticum Schulze & Schlottke, 1930 (13.5%), H. marginatum Koch, 1844 (27.01%), H. detritum Schulze, 1919 (9.67%), H. schulzei Olenev, 1931 (4.03%) and H. dromedary Koch, 1844 (4.33%) were recorded. The results indicated that H. anatolicum, H. asiaticum, H. marginatum and H. detritum were present in all zones whereas H. excavatum was absent in Zone I. The result also showed that H. dromedari was presented in Zones III and IV whereas H. schulzei was present in Zones II and III. During this study, the tick species collected are candidates for investigation as vectors of pathogenic organisms in Iran.     

Book Review

Book reviewed in this article:
BASIC FOOD MICROBIOLOGY (1979). G. J. Banwart.
BACTERIA AND HUMAN DISEASE (1979). J. M. Slack and I. S. Snyder.
ANTIBIOTICS. Volume 5 (in two parts). PART 1: MECHANISM OF ACTION OF ANTIBACTERIAL AGENTS. PART 2: MECHANISM OF ACTION OF ANTIEUKARYOTIC AND ANTIVIRAL COMPOUNDS (1979). Part 1, 376 pp., Part 2, 470 pp. Edited by F. E. Hahn.
COMBINED ANTIMICROBIAL THERAPY (1979). Edited by W. Brumfitt, L. Curcio and L. Silvestri.
DEVELOPMENTAL BIOLOGY OF PROKARYOTES (1979). Edited by J. H. Parish.
ADHESION OF MICRO-ORGANISMS TO SURFACES (1979). Edited by D. C. Ellwood, J. Melling and P. Rutter.
MICROBIAL CLASSIFICATION AND IDENTIFICATION (1980). Edited by M. Goodfellow and R. G. Board.
FUNDAMENTALS OF FOOD CANNING TECHNOLOGY (1979). J. M. Jackson and B. M. Shinn.
MICROTUBULES (1979). Edited by K. Roberts and J. S. Hyams.
FOOD-BORNE INFECTIONS AND INTOXICATIONS (1979). Edited by H. Riemann and F. L. Bryan.
REGULATION OF MACROMOLECULAR SYNTHESIS BY LOW MOLECULAR WEIGHT MEDIATORS (1979). Edited by G. Koch and D. Richter.     

A hydraulic-photosynthetic model based on extended HLH and its application to Coast redwood (Sequoia sempervirens)

Although recent investigations [Ryan, M.G., Yoder, B.J., 1997. Hydraulic limits to tree height and tree growth. Bioscience 47, 235-242; Koch, G.W., Sillett, S.C.,Jennings, G.M.,Davis, S.D., 2004. The limits to tree height. Nature 428, 851-854; Niklas, K.J., Spatz, H., 2004. Growth and hydraulic (not mechanical) constraints govern the scaling of tree height and mass. Proc. Natl Acad. Sci. 101, 15661-15663; Ryan, M.G., Phillips, N., Bond, B.J., 2006. Hydraulic limitation hypothesis revisited. Plant Cell Environ. 29, 367-381; Niklas, K.J., 2007. Maximum plant height and the biophysical factors that limit it. Tree Physiol. 27, 433-440; Burgess, S.S.O., Dawson, T.E., 2007. Predicting the limits to tree height using statistical regressions of leaf traits. New Phytol. 174, 626-636] suggested that the hydraulic limitation hypothesis (HLH) is the most plausible theory to explain the biophysical limits to maximum tree height and the decline in tree growth rate with age, the analysis is largely qualitative or based on statistical regression. Here we present an integrated biophysical model based on the principle that trees develop physiological compensations (e.g. the declined leaf water potential and the tapering of conduits with heights [West, G.B., Brown, J.H., Enquist, B.J., 1999. A general model for the structure and allometry of plant vascular systems. Nature 400, 664-667]) to resist the increasing water stress with height, the classical HLH and the biochemical limitations on photosynthesis [von Caemmerer, S., 2000. Biochemical Models of Leaf Photosynthesis. CSIRO Publishing, Australia]. The model has been applied to the tallest trees in the world (viz. Coast redwood (Sequoia sempervirens)). Xylem water potential, leaf carbon isotope composition, leaf mass to area ratio at different heights derived from the model show good agreements with the experimental measurements of Koch et al. [2004. The limits to tree height. Nature 428, 851-854]. The model also well explains the universal trend of declining growth rate with age.     

Discussion on the Validity of Roegneria C. Koch (Gramineae) as Genus by Numerical Taxonomic Method

This paper deals with the systematic position of Gen. Roegneria C. Koch by numerical taxonomic method. The genus Roegneria C. Koch and its relatively related genera (Agropyron Gaerth., Elymus L., Elytrigia Desv., Leymus Hochst.) were selected as OTUS. The numerical classification was based on 30 characters, of which 18 are morphological (gross and microscopic) and 12 cytological. The dendrogram (Fig. 1.) is the optimal one, which is selected according to the cophenetic correlation coefficient. Moreover, the results of other cluster methods, which are based on either the correlation coefficient or the distance coefficients, show the same structure similar to the Fig. 1. Hance, Gen. Roegneria is considered congeneric with Gen. Elymus. According to the priority of International Code, Gen. Roegneria C. Koch should be referred to Gen. Elymus L.     

中国纵脊叶蜂属分类研究（膜翅目：叶蜂科）

厘订了中国纵脊叶蜂属Xenapatidea Malaise种类,并记述1个新种——方顶纵脊叶蜂Xenapatidea reticulata sp. nov.和1个中国新纪录种——红胸纵脊叶蜂 Xenapatidea rufoscutellata Koch, 1996。首次报道并描述了X. rufoscutellata Koch, 1996的雌性。编制了纵脊叶蜂属8个已知种分种检索表。新种模式标本保存于中南林业科技大学昆虫标本馆。     

The life cycle and generic position of Aphis tremulae L., 1761 (Aphidoidea: Pemphiginae), with a description of the viviparous morphs and a discussion of spruce root aphids in the British Isles

An account is given of the biology of Aphis tremulae L., confirming its heteroecy from Populus tremula L. to roots of Picea abies (L.) Karst. The viviparous morphs from both hosts are described. The identity of British aphids from spruce roots is discussed. Aphis tremulae is placed in the genus Pachypappa Koch, of which Astphum Koch becomes a subjective synonym. A key is given to the viviparous morphs of the known British genera of Pemphiginae.     

Active chloride secretion by rabbit colon: calcium-dependent stimulation by ionophore A23187.

Addition of Ca ionophore, A23187, to the solution bathing the mucosal surface of descending rabbit colon resulted in a reversal of active C1absorption to active C1 secretion, a twofold increase in short-circuit current and a 40% increase in tissue conductance without affecting the rate of active Na absorption. These alterations in electrolyte transport are quantitatively similar to those previously observed in response to cyclic 3',5'-AMP (cAMP) (RA. Frizzell, M.J. Koch & S.G. Schulz, J. Membrane Biol. 27:297, 1976). When medium Ca concentration was reduced to 10(-6) M, the secretory response to A23187 was abolished but the response to cAMP was unaffected. The ionophore did not influence the cAMP levels of colonic mucosa. Addition of cyclic AMP to colonic strips preloaded with 45Ca elicited a reversible increase in Ca efflux from the tissue. These results suggest that an increase in intracellular Ca concentration stimulates colonic electrolyte secretion and that the secretory response to cAMP may be due, at least in part, to a release of Ca from intracellular stores.