Glycoprotein Characterization of the Gelatinous Matrix in the Root-knot Nematode Meloidogyne javanica

Proteinaceous components of freshly formed gelatinous matrix (GM) of the root-knot nematode Metoidogyne javanica were analyzed. Under reducing conditions, the prominent protein fragments had molecular weights of 26 to 66 kDa and 150 to >200 kDa, and most were glycosylated. Most of the fragments were digested by proteinase K, and fewer by trypsin. The lectins soybean agglutinin (SBA), Ulex europaeus agglutinin, and wheat germ agglutinin labeled the higher molecular weight bands (i.e., >200 kDa). SBA labeled additional protein fractions between 26 and 66 kDa. Although Bandeiraea simplicifolia lectin and Concanavalin A did not label bands on the Western blot, they did label the GM in the dot blot technique. Analysis of amino acids and amino sugars in the GM revealed an unusually high amount of ammonia and galactosamine moieties.     

Effects of Hydroxyurea on the Ultrastructure of Giant Cells in Galls Induced by Meloidogyne javanica

Hydroxyurea (HU) at concentrations of 10 or 20 mg/liter was included in a medium on which excised tomato roots infected with the root-knot nematode Meloidogyne javanica were grown. In the HU, treated roots, giant cells were small and contained large vacuoles. Giant cell nuclei were amoeboidal with relatively small nucleoli in treated roots, compared with giant cells of nontreated galls. In treated-root giant cells, the cytoplasm was diffuse and few organelles such as mitochondria, dictyosomes, and endoplasmic reticulum were detected; also, walls of giant cells were thin with less extensive ingrowths than in nontreated roots. We conclude that HU suppressed normal giant cell formation interfering with its function as a feeding cell.     

桉树枝瘿姬小蜂成虫感器超微结构

应用扫描电镜对桉树枝瘿姬小蜂Leptocybe invasa Fisher & LaSalle成虫触角、复眼、口器、足以及腹部末端感器的超微结构和分布进行观察。结果表明,在触角上共有8种感器,分别为Bhm氏鬃毛Ⅰ、Bhm氏鬃毛Ⅱ、刺形感器、毛形感器Ⅰ、毛形感器Ⅱ、板形感器Ⅰ、板形感器Ⅱ和钟形感器;口器上有2种感器,分别为毛形感器Ⅳ和刺形感器;在足上有4种感器,分别为毛形感器Ⅰ、毛形感器Ⅲ、刺形感器和锥形感器;在腹部末端也有3种感器,分别为毛形感器Ⅰ、刺形感器和腔形感器。同时还探讨了触角上各种感器的功能。     

Influence of Temperature on Embryogenesis in Meloidogyne javanica

The optimum temperature for embryogenesis in Meloidogyne javanica lies between 25 and 30 C. Embryogenesis is slightly more rapid at 30 C (9-10 days), but more eggs complete development at 25 C (11-13 days). At temperatures of 25, 27.5, and 30 C, embryogenesis is about twice as rapid as at 20 C (23-25 days), and about four times as rapid as at 15 C (46-48 days). Time-lapse studies showed that the thermal optimum is similar throughout the different stages of embryonic development.     

Identification of resistance to Meloidogyne javanica in the Lycopersicon peruvianum complex

Clones of Lycopersicon peruvianum PI 2704352R2, PI 270435-3MH and PI 126443-1MH expressed novel resistance to three Mi-avirulent M. javanica isolates in greenhouse experiments. Clones from PI 126443-1MH were resistant to the three M. javanica isolates at 25°C. The three isolates were able to reproduce on one embryorescue hybrid of PI 126443-1MH, but not on three L. peruvianum-L. esculentum bridge-line hybrids of PI 1264431MH when screened at 25°C (Mi-expressed temperature). Clones of PI 270435-2R2 and all its hybrids with susceptible genotypes were resistant to the three M. javanica isolates at 25°C. The bridge-line hybrid EPP-2xPI 2704352R2 was susceptible to M. javanica isolate 811 at 32°C, whereas PI 270435-2R2 and all other hybrids of PI 27043 5-2R2 crossed with susceptible genotypes were resistant at 32°C. At 32°C, one F₂ progeny of PI 126443-IMHxEPP-1, and three test-cross progenies of PI 1264409MHx[PI 270435-3MHxPI 126443-1MH], and reciprocal test-cross progenies of [PI 270435-3MHxPI 2704352R2]xPI 126440-9MH, each segregated into resistant: susceptible (RS) ratios close to 31. The results from the F₂ progeny indicated that heat-stable resistance to Mi-avirulent M. javanica in PI 126443 -1MH is conferred by a single dominant gene. The results from the test-crosses indicated that this gene in PI 126443-1MH is different from the resistance gene in PI 270435-3MH. The resistance gene in PI 270435-3MH was also shown to differ from the resistance factor in PI 270435-2R2. The expression of differential susceptibility and resistance to M. javanica and M. incognita in individual plants of the bridge-line hybrid, embryo-rescue hybrid, F₂, and test-crosses indicated that at least some genes governing resistance to M. javanica differ from the genes conferring resistance to M. incognita. A new source of heat-stable resistance to M. javanica was identified in Lycopersicon chilense.     

Inheritance of resistance to the root-knot nematode Meloidogyne javanica in lettuce

Resistance to the root-knot nematodes Meloidogyne spp. would be a valuable attribute of lettuce Lactuca sativa L. cultivars grown in tropical regions. The looseleaf lettuce 'Grand Rapids' is resistant to both M. incognita and M. javanica. Resistance to M. incognita has a high heritability, under the control of a single gene locus, in which the 'Grand Rapids' allele, responsible for resistance (Me), has predominantly additive gene action, and has incomplete penetrance and variable expressivity. We studied the inheritance of the resistance of 'Grand Rapids' (P(2)) to M. javanica in a cross with a standard nematode-susceptible cultivar Regina-71 (P(1)). F(1)(Regina-71 x Grand Rapids) and F(2) seed were obtained, and the F(2) inoculated, along with the parental cultivars, with a known isolate of M. javanica to evaluate nematode resistance. A high broad sense heritability estimate (0.798) was obtained for gall indices. Class distributions of gall indices for generations P(1), P(2), and F(2) were in agreement with theoretical distributions based on a monogenic inheritance model for the range of assumed degrees of dominance between approximately -0.20 and 0.20. M. javanica resistance appears to be under control of a single gene locus, with predominantly additive gene action. Whether or not the Grand Rapids allele imparting resistance to M. javanica is the same Me allele imparting resistance to M. incognita remains to be determined.     

Partial Characterization of the Cuticle Surface of Meloidogyne javanica Females

Negative charges on the outer cuticular surface of Meloidogyne javanica females were visualized with electron microscope labelling techniques. Evidence is presented that the electronegative charge is not borne on neuraminic acid. Ruthenium red staining indicated acid mucopolysaccharides on the outer surface. A surface coat, or glycocalyx, external to the outer cuticle membrane was demonstrated.     

Changes in the Ultrastructure of Adrenocortical Cells Induced by Cholinergic Agonists

The role of cholinergic neurotransmitters in the changes in ultrastructure of adrenocortical cells remains to a great extent unexplored. We studied the influence of acetylcholine (ACh) and pilocarpine, agonists of muscarinic ACh (mACh) receptors, on the ultrastructure of adrenocortical secretory cells derived from the rat adrenal cortex. Both agonists were found to stimulate fragmentation of the mitochondria and lipid droplets and reconstruction of the peroxisomal compartment. At the same time, assembling of the smooth endoplasmic reticulum (sER) membranes was observed after ACh application, while pilocarpine action was not always prominent. Thus, we conclude that activation of mACh receptors by its agonists influence the ultrastructure of the adrenocortical cells, and the respective ACh-induced effects are more intensive.     

Changes in Chloroplast Ultrastructure in Pssu-ipt Tobacco During Plant Ontogeny

Changes in chloroplast ultrastructure and total content of endogenous cytokinins (CK) were studied during different phases of plant development in transgenic Pssu-ipt tobacco (Nicotiana tabacum L. cv. Petit Havana SR1). Permanent overproduction of CK was found in both rooted (SE) and grafted (G) Pssu-ipt plants in all phases of plant development with the peak in vegetative and flowering phase in the latter ones. No such a correlation was observed in SE on the contrary to control non-transgenic plants (SR1) and grafts (SRG), which showed also CK increase at juvenile and flowering phases. No significant differences in parameters of chloroplast ultrastructure, such as length of chloroplast, starch content, granum width, and number of thylakoids per granum, were proved between chloroplasts from young mature leaves of control and transgenic tobacco during plant ontogeny. Nevertheless, several anomalies in the ultrastructure of cell organelles were found in Pssu-ipt tobacco. Amoeboid shape of chloroplasts was often observed in connection with tubular clusters resembling peripheral reticulum. The distinct crystalline structures located in chloroplasts might be formed by LHC protein aggregates. Smaller crystals of unknown composition were found also in mitochondria. Numerous crystalline cores were present in peroxisomes. The alterations might be the result of imbalance of phytohormone content, degradation effect of CK overproduction, or the example of acclimation to permanent stress.     

不同fimA基因型牙龈卟啉单胞菌超微结构观察

目的 探查具有不同粘附、侵入能力的各fimA基因型P.gingivalis菌体表面结构特点.方法 选取临床培养的经PCR鉴定、筛选的fimA基因Ⅰ、Ⅱ和Ⅳ型P.gingivalis野生菌株,制备超薄切片,在透射电镜下进行菌体表面结构观察.结果 fimA基因Ⅰ、Ⅱ和Ⅳ型P.gingivalis的菌毛存在差别：Ⅰ型和Ⅱ型菌体表面有放射状菌毛,Ⅱ型略显致密,Ⅳ型表面未见明显菌毛.同时也观察到各型荚膜存在差别：Ⅰ型荚膜最厚,Ⅳ型荚膜较薄,Ⅱ型荚膜最薄.结论 fimA基因Ⅰ、Ⅱ和Ⅳ型P.gingivalis的菌毛和荚膜存在较大差别,推测其粘附、侵入或其它致病能力的差异可能不仅与菌毛有关,还与荚膜或其它因素有关.     

Suppression of Embryogenesis and Hatching in Meloidogyne javanica by Thermal Stress

Embryogenes is and hatching of eggs of Meloidogyne javanica were suppressed by brief heat treatment (46 C for 10 min). The period of suppression or arrested development differs according to the stage of development of the nematode when heat treatment is applied. The effect on hatching is much more pronounced than on embryogenesis.     

Ultrastructure and distribution of the taste buds in the buccal cavity in relation to the food and feeding habit of a herbivorous fish: Oreochromis niloticus

The buccal cavity of an herbivorous fish Oreochromis niloticus was investigated by means of scanning electron microscopy. The buccal cavity distinguished into the roof and the floor. Three different types of taste buds (type I, II and III) are distributed in the buccal cavity. The proximal part of the buccal cavity bears relatively high epidermal papillae in which type I TBs was found. The middle region of the buccal cavity is mostly occupied by low epidermal papillae containing type II TBs. Type III TBs which are present within the metabranchial buccal cavity; never rise above the normal level of the epithelium.The different types of TBs are useful for ensuring full utilization of the gustatory ability of the fish. It is postulated that the TBs serve different functions: TBs type I and II may act as chemoreceptors and mechanoreceptors. TBs type III acts predominantly as a chemoreceptors. TBs of each type show two kinds of receptor villi within their receptor areas: tall villi and small villi. The surface of the lining epithelial cells shows a delicate microridge system. These structures protect against physical abrasion potentially caused during food maneuvering and swallowing. Furthermore, protection of the epithelium from abrasion is enhanced with goblet cells secretion.     

Interaction of Meloidogyne hapla and M. javanica Infecting Tomato

A soil temperature of 20 C was equally suitable for the invasion and development of M. hapla and M. javanica. However, M. javanica predominated in a mixed species infection at this temperature. Predominance increased with increasing mixed-species inoculum levels. Invasion by M. hapla was more density-dependent than M. javanica. M. hapla produced a greater incidence of terminal galls and lateral roots.     

Pathogenic Variability Among Isolates of Meloidogyne javanica on Capsicum annum

Meloidogyne javanica isolates were collected from nine districts of Uttar Pradesh. These isolates showed pathogenic variability when inoculated on the pepper cultivars California Wonder and Suryamukhi Green. Meloidogyne javanica that infected Suryamukhi Green but not California Wonder were designated as pepper race 1 and the populations that infected both the cultivars were designated pepper race 2. Race 1 was more frequent than race 2 in Almora, Pauri Garhwal, Basti, Gorakhpur, and Deoria, whereas race 2 was more frequent than race 1 in the Dehradun, Farrukhabad, Hardoi, and Sitapur districts. The overall frequencies were 70% and 30% for race 1 and race 2, respectively, in the study area.     

改良透射电镜方法观察小鼠ICSI胚胎核仁超微结构

小鼠植入前胚胎的发育过程中,核仁经历从简单到复杂、从致密结构到网状结构的变化。对核仁超微结构的观察有助于揭示早期胚胎发育过程中核仁结构的动态变化及其特定阶段的功能。但由于核仁结构微小,数目较少,并且在胚胎中只处于卵裂球细胞核的内部,难以定位,因而给核仁的超微结构观察带来很大的困难。本实验探索了透射电镜观察小鼠植入前胚胎核仁的方法:先用琼脂对小鼠胚胎进行预包埋,在经过常规的透射电镜样品制备流程后,将整个胚胎先切成半薄切片;经过甲苯胺蓝染色后,选取含核仁结构的切片进行重包埋;最后再对回收来的半薄切片进行超薄切片,醋酸铀染色后上电镜观察;最终成功获得小鼠胚胎植入前发育不同时期核仁清晰的透射电镜图像。     

荔枝雄花性别决定过程中细胞超微结构的变化

荔枝雄花雌蕊原基在大孢子母细胞减数分裂后开始衰退.内质网历经增生扩展,穿壁相连,同心缠绕,多条平行弯曲,不规则堆叠.内质网和高尔基体产生许多囊泡,囊泡在细胞内含物的降解和运输过程中起着重要的作用.线粒体在雌蕊原基细胞衰败的前、中期数量增加,后期分批降解.过氧化物酶体在雌蕊原基细胞衰败的中期紧挨核短暂出现.细胞核的染色质凝集断裂;核周腔扩大,形成胀泡;染色质趋边,外泄.细胞原生质表现出有序的、在膜包裹下的降解,首先是核糖体,而后依次是:过氧化物酶体、内质网、高尔基体、线粒体、核.雌蕊原基的衰败历程可能是一种程序性细胞死亡的过程.     

Extracellular Matrix Surface Network During Plant Regeneration in Wheat Anther Culture

Androgenic plant regeneration from wheat anther callus was accompanied by the formation of a conspicuous extracellular matrix surface network (ECMSN) around the induced callus cells and young embryo-like structures. Microscopic observations at the onset of regeneration revealed the presence of two distinct types of cells on the callus surface: large, loosely attached parenchymatous cells and small tightly packed meristematic cells arranged in multicellular clusters. Parenchyma cells of the callus had smooth surface, while on the surface and between the cells of multicellular clusters numerous fine fibrils of ECMSN were observed. The structural arrangement of the ECMSN changed during culture. On the surface of globular embryo-like structures, before protoderm formation, the ECMSN was the most abundant and arranged as a compact layer of secretion with wide strands visible at the cell junctions. Further development of globular embryos was disturbed, giving rise to branched structures outlined by continuous epidermis. The development of such regenerants was accompanied by gradual degradation of the extracellular network and finally its complete disappearance. Digestion with protease did not destroy the network. Treatment of the calluses with chloroform and washing with ether–methanol led to partial destruction of the network, while digestion with pectinase removed the network completely and resulted in the collapse of surface embryo cells.     

Control of Meloidogyne javanica by Formulations of Inula viscosa Leaf Extracts

Inula viscosa is a perennial plant that is widely distributed in Mediterranean countries. Formulations of I. viscosa extracts were tested for their effectiveness in control of Meloidogyne javanica in laboratory, growth chamber, microplot, and field experiments. Oily pastes were obtained by extraction of dry leaves with a mixture of acetone and n-hexane or n-hexane alone, followed by evaporation of the solvents. Emulsifiable concentrate formulations of the pastes killed M. javanica juveniles in sand at a concentration of 0.01% (paste, w/w) or greater and reduced the galling index of cucumber seedlings as well as the galling index and numbers of nematode eggs on tomato plants in growth chamber experiments. In microplot experiments, the hexane-extract formulation at 26 g paste/m² reduced nematode infection on tomato plants in one of two experiments. In a field experiment, a reduction of 40% in root galling index by one of two formulations was observed on lettuce plants. The plant extracts have potential as a natural nematicide, although the formulations need improvement.     

Ultrastructure of the tail region of the second stage preparasitic larva of the root-knot nematode

Studies on the tail of second-stage infective larvae (L₂s) of Meloidogyne javanica, M. incognita and M. hapla from a region anterior to the rectal gland to the tail tip have revealed the presence of a previously undescribed sensory organ, the caudal sensory organ, in the posterior region of the tail.The extreme tip of the tail consists of solid cuticle and the different zones of this structure are described throughout the tail region. Longitudinal sections through the anus and rectum have revealed that the cortical (external cortical, epicuticle) layer gradually decreases in thickness until its outermost layer appears to merge with the plasma membrane of the rectal inflation or gland. This gland appears to be similar in all three species studied.The two phasmidial glands and their canals are described from transverse sections. Somatic muscle is first found in the region of the anus and it extends anteriorly throughout most of the length of the L₂. Depressor ani muscles which insert on the dorsal surface of the rectum are also described.The rectal gland in the dilated state occupies about three quarters of the diameter of the L₂. It contains a matrix which resembles that extruded from the adult female rectal gland cells. The rectal gland cells contain large amounts of rough endoplasmic reticulum and desmosomes are found close to the junction of these cells and the plasma membrane of the gland itself. More anteriorly in the L₂ most of the area is taken up by large lipid droplets which function as an energy reserve.It is suggested that the rectal gland should not be used as a taxonomic criterion for separating the La_2^S of Meloidogyne because it can vary so much in appearance within the same species.