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421.
422.
In 1979, the walnut spanworm defoliated a 1 ha bitterbrush seed orchard near Nephi, Utah. No seed was produced for two years thereafter due to feeding damage. Life stages were described and illustrated. The female is brachypterous and incapable of flight. First instar larvae readily drop on their silk threads and probably are dispersed by wind. The insect has one annual generation. Moths laid an average of 159 eggs per cluster in April; larvae began to appear in early May and matured by the first week of June. The pupal period extended from June until mid-April. The parasitic bombyliid, Villa faustina (Osten Sacken), was reared from pupae. In April 1980, shrubs contained an estimated average of 1044 eggs each. On 19 May, larvae averaged 1.9 per 7.5 cm of twig and were in the first and second instar. On 20 May the population was controlled by spraying with Sevimol-4. Other potential host plants, as determined from greenhouse tests, are rose, ceanothus, mountain mahogany, serviceberry, and willow. 相似文献
423.
Sara C. Gillespie Dirk H. Van Vuren Douglas A. Kelt John M. Eadie Daniel W. Anderson 《西北部美国博物学家》2011,68(1)
From 1996 to 2004, we studied population dynamics of a rodent assemblage in semiarid habitats in Lassen County, California. Abundances of rodents appeared affected by fluctuations in precipitation from a high in 1996 to average and slightly below-average levels in subsequent years; perhaps reflecting this, assemblage composition also changed dramatically during the study period. California kangaroo rats ( Dipodomys californicus ) declined from abundant to extremely rare, abundances of deer mice ( Peromyscus maniculatus ) fluctuated greatly during the study period, and, perhaps most notably, populations of dusky-footed woodrats ( Neotoma fuscipes ) appeared to decline to local extinction, possibly allowing for the subsequent colonization of desert woodrats ( N. lepida ). These changes appeared to represent natural variation in numbers and composition in an ecologically dynamic ecotonal region in response to multiyear changes in precipitation. 相似文献
424.
425.
Koen Van Crombruggen Fenila Jacob Nan Zhang Claus Bachert 《Cellular and molecular life sciences : CMLS》2013,70(22):4307-4321
Inflammation of the nasal (rhinitis) and sinus mucosa (sinusitis) are prevalent medical conditions of the upper airways that are concurrent in many patients; hence the terminology “rhinosinusitis”. The disease status is further defined to be “chronic” in case symptoms persist for more than 12 weeks without resolution. A diverse spectrum of external factors including viral and bacterial insults together with epithelial barrier malfunctions could be implicated in the chronicity of the inflammatory responses in chronic rhinosinusitis (CRS). However, despite massive research efforts in an attempt to unveil the pathophysiology, the exact reason for a lack of resolution still remains poorly understood. A novel set of molecules that could be implicated in sustaining the inflammatory reaction may be found within the host itself. Indeed, besides mediators of inflammation originating from outside, some endogenous intracellular and/or extracellular matrix (ECM) components from the host can be released into the extracellular space upon damage induced during the initial inflammatory reaction where they gain functions distinct from those during normal physiology. These “host-self” molecules are known to modulate inflammatory responses under pathological conditions, potentially preventing resolution and contributing to the development of chronic inflammation. These molecules are collectively classified as damage-associated molecular patterns (DAMPs). This review summarizes the current knowledge regarding DAMPs in upper airway pathologies, also covering those that were previously investigated for their intracellular and/or ECM functions often acting as an antimicrobial agent or implicated in tissue/cell homeostasis, and for which their function as a danger signaling molecule was not assessed. It is, however, of importance to assess these molecules again from a point of view as a DAMP in order to further unravel the pathogenesis of CRS. 相似文献
426.
The mechanisms that generate the immense complexity of synaptic connections within the developing nervous system have fascinated biologists for decades. Analysis of nervous system development in simple systems, such as insects, has made a major contribution to our understanding of the cellular and molecular mechanisms that control the formation of axon pathways and precise connections. This enterprise has a long, interesting, and somewhat controversial history. This collection of reviews on axon guidance in insects provides a brief update to integrate current molecular and developmental insights in a number of areas from initial axon pathfinding to the recognition of synaptic partners. 相似文献
427.
T.Van Ree V.Bologo 《复旦学报(自然科学版)》2007,(5)
1 Results Natural products,and especially those extracted from higher plants,have for many years served as new leads for new pharmaceuticals.We here report on the multi-step synthesis of 1-O-steryl 6-O-acyl glucosides,synthetic analogues which are structurally related to the mixture of natural products (1) extracted from the plant Flacourtia indica[1],that may be used medicinally for their anti-tumor activities.See Fig.1. 相似文献
428.
L Hendriks C M van Duijn P Cras M Cruts W Van Hul F van Harskamp A Warren M G McInnis S E Antonarakis J J Martin 《Nature genetics》1992,1(3):218-221
Several families with an early-onset form of familial Alzheimer's disease have been found to harbour mutations at a specific codon (717) of the gene for the beta-amyloid precursor protein (APP) on chromosome 21. We now report, a novel base mutation in the same exon of the APP gene which co-segregates in one family with presenile dementia and cerebral haemorrhage due to cerebral amyloid angiopathy. The mutation results in the substitution of alanine into glycine at codon 692. These results suggest that the clinically distinct entities, presenile dementia and cerebral amyloid angiopathy, can be caused by the same mutation in the APP gene. 相似文献
429.
Complex microtubule assemblies are essential components of eukaryotic cilia and flagella. They are extremely stable and are not affected by agents that normally induce polymer disassembly. The molecular basis of this microtubular stability is unknown, and it is not related to any feature of the constitutive tubulin. In sea urchin sperm flagella, axonemal microtubules are found to be stabilized by a protein identical to histone H1, a result that defines a new role for this histone and provides evidence for a concerted evolution of chromatin and microtubular structures. 相似文献
430.
Immunocytochemical techniques applied at both light- and electron microscopical levels are valuable in the study of regulatory peptide distribution in normal and diseased tissue, whether in the form of sections or whole cell preparations. Successful immunolocalization depends on adequate preservation of the peptide antigen and the tissue structure in which it resides; a suitably specific and sensitive labelled antibody detecting system. In general, peptides are stable molecules, most of which retain their antigenicity after conventional cross-linking fixation and tissue processing, allowing standard immunocytochemical methods to be used for light- and electron microscopy. Regulatory peptides are derived from precursor molecules and several 'families' of structurally similar peptides are now generally recognised. Region-specific antibodies may be needed to overcome problems of cross-reactivity or to identify a bioactive form in the presence of its precursor. Multiple co-localisation of different related and unrelated peptides in the same cell or even storage granule is now recognised and can be identified by immunocytochemistry. 相似文献