Effects of Temperature,Shoot Age,and Medium on Gall Induction by Subanguina picridis in Vitro

The influence of temperature, shoot age, and medium on gall induction by Subanguina picridis on Russian knapweed (Acroptilon repens) was examined in vitro. The optimal temperature for gall formation was 20 C. Gall induction was delayed as the temperature decreased, and decreased as shoot age increased. Bud primordia (0-day-old shoots and 5-day-old shoots) with an average length of 4.2 mm and 7.9 mm were the most suitable tissues for nematode development and gall formation. Gall formation was more effective on B5G medium than on MSG. Young shoots under slow growth were most suitable for mass rearing of S. picridis.     

An In Vitro Test for Temperature Sensitivity and Resistance to Meloidogyne incognita in Tomato

An in vitro root explant tissue culture technique is described for determining susceptibility of tomato (Lycopersicon esculentum Mill.) breeding lines and cultivars to the root-knot nematode Meloidogyne incognita. Root explants were taken from 2-day-old seedlings cultured for 30 days at 28 C on Gamborg''s B-5 medium with or without nematode inoculum. The remaining portion of the root and stem from the excised root explants was transferred to soil in pots and grown to maturity in the greenhouse. In vitro root explants were evaluated for growth and occurrence of juveniles, adults, and egg masses. The regenerated plants were used to produce more seed, The proposed technique is simple, reliable, and adapted to routine screening of large numbers of F₁ and F₂ samples, and it utilizes less space than tests performed on intact plants in the greenhouse or growth chamber. Evidence is presented also on the breakdown of resistance to M. incognita under high temperature stress using this in vitro root explant technique.     

Effects of Chronic Basic Fibroblast Growth Factor Administration to Rats with Partial Flmbrial Transections on Presynaptic Cholinergic Parameters and Muscarinic Receptors in the Hippocampus: Comparison with Nerve Growth Factor

Abstract: The present study compares the effects of chronic administration of basic fibroblast growth factor (bFGF) and nerve growth factor (NGF) on various hippocampal cholinergic parameters in rats with partial unilateral fimbrial transections. Lesions resulted in marked reductions of several presynaptic cholinergic parameters: choline acetyltransferase (ChAT) activity (by 50%), [³H]-acetylcholine ([³H]ACh) synthesis (by 59%), basal and ve-ratridine (1 μM)-evoked [³H]ACh release (by 44 and 57%, respectively), and [³H]vesamicol binding site densities (by 35%). In addition, [³H]AF-DX 116/muscarinic M₂ binding site densities were also modestly decreased (by 23%). In contrast, [³H]pirenzepine/muscarinic M₁ and [³H]AF-DX 384/muscarinic M₂/M₄ binding site densities were not altered by the lesions, nor were they affected by any of the treatments. Intracerebroventricular administration of bFGF (10 ng, every other day, for 21 days) partially prevented the lesion-induced deficit in hippocampal ChAT activity, an effect that was not markedly different from that measured in the NGF-treated (1 μg intracerebroventricularly, every other day, for 21 days) rats. In rats treated with a combination of bFGF and NGF, ChAT activity was not different from that in rats treated with the individual factors alone. In contrast, the lesion-induced deficits in the other cholinergic parameters were not attenuated by bFGF treatment, although they were at least partially prevented by NGF administration. To determine whether higher concentrations of bFGF are necessary to affect cholinergic parameters other than hippocampal ChAT activity, rats were treated with 1 μg (every other day, 21 days) of the growth factor. In this group of rats, detrimental effects of bFGF, manifested by an increased death rate (46%), and marked reductions in body weight of the survivors, were observed. In addition, this concentration of bFGF appeared to exacerbate the lesion-induced reduction in [³H]ACh synthesis by hippocampal slices; [³H]ACh synthesis in lesioned hippocampi represented 36 and 52% of that in contralateral unlesioned hippocampi for the bFGF-treated and control groups, respectively. In conclusion, although bFGF administration attenuates the deficit in hippocampal ChAT activity induced by partial fimbrial transections, this does not appear to translate into enhanced functional capacity of the cholinergic terminals. This is clearly in contrast to NGF, which enhances not only hippocampal ChAT activity, but also other parameters indicative of increased function in the cholinergic terminals.     

Survey of Heterorhabditidae and Steinernematidae (Rhabditida,Nematoda) in Western Canada

A survey was done in the summer months along the Alaska Highway, in other parts of British Columbia, in northern Alberta, and in the Yukon Territory for steinernematid and heterorhabditid nematodes occurring in the top 10 cm of soil. Steinernema feltiae and Steinernema spp. were found at 18 and Heterorhabditis megidis at 7 sites of 125 sampled. Most nematodes were found where visible insect infestation occurred and where human influence on the habitat was substantial (e.g., agricultural, forested and bush-hedgerow habitats); none was found in grassland or virgin forests. Heterorhabditis megidis occurred in only the southern, warmer, drier region of British Columbia. In the laboratory some steinernematid isolates and H. megidis killed Galleria mellonella larvae at 13 and 22 C, whereas some isolates of Steinernema killed the larvae at only 13 C. Steinernema spp. from three high altitude sites with low, average July temperatures (13-14 C) are cold-active in that they produced infective juveniles at 13 C and killed G. mellonella at 6 C.     

Extent of polyteny in the pericentric heterochromatin of polytene chromosomes of pseudonurse cells of otu (ovarian tumor) mutants of Drosophila melanogaster

In the polytene nuclei of germ-line cells (ovarian pseudonurse cells) of Drosophila melanogaster females mutant for otu ¹¹ (ovarian tumor), the pericentric heterochromatin is much more abundant than in somatic salivary gland cells. This is due to the degree of heterochromatin compaction (and consequently the level of underreplication) being lower in the nurse cells than in the salivary gland cells. The lower level of compaction probably results in a very low degree of position effect gene inactivation in the ovarian nurse cells.     

草鱼、鲤、鲢、鳙和尼罗罗非鱼肝胰脏和肠道蛋白酶活性的初步探讨

草鱼、鲤、鲢、鳙肝胰脏和肠蛋白酶的最适pH值分别为8.7、8.7、7.6、7.6和8.4、8.7、8.0、8.4。草鱼、鲤和尼罗罗非鱼的肝胰脏蛋白酶活性比肠的高;鲢和鳙的肝胰脏蛋白酶的活性却比肠的低;尼罗罗非鱼胃的蛋白酶活性明显高于肝胰脏和肠的。草鱼、鲤和尼罗罗非鱼的肝胰脏蛋白酶活性明显高于鲢和鳙的;5种鱼的肠蛋白酶活性,鲤最高,尼罗罗非鱼最低,草鱼、鲢、鳙和尼罗罗非鱼间蛋白酶活性无明显差异。草鱼、鲤、鲢和尼罗罗非鱼的肠蛋白酶活性由前向后递减,而鳙的则以中肠活性最高。     

安徽宿县夹沟寒武-奥陶系界线附近生物群演变及地球化学特征

对宿县夹沟地区跨寒武系与奥陶系的三山子组的碳、氧同位素和微量元素地球化学的研究表明,寒武－奥陶系界线附近有δ＾１３Ｃ和δ＾１８Ｏ的负异常,亲铁元素、亲铜元素的正异常。这些异常与生物群面貌的变化在时间上是同步的。据此认为研究区在寒武纪末可能存在灾变事件。同时,考虑到寒武纪末和奥陶纪初生物群面貌的重大差异,综合国内,外有关研究,认为寒武纪末期可能存在全球性的重大地质事件。     

Effect of meteorological variates on persistence of primary conidia and capilliconidia of Erynia radicans (Zygomycotin: ntomophthorales) under natural conditions

Persistence of conidia of an isolate of Erynia radicans (Syn. Zoophthora radicans) was investigated in relation to the meteorological conditions which occurred during autumn-winter of 1990–91 in the coastal plain in Israel. Capilljconidia shielded from the sun, placed on the abaxial surface of leaves of Plumeria acuminata, persisted for 24 h to at least 120 h. Exposed capilliconidia, placed on the adaxial surface of the same leaves, died within 24 h. Almost all the primary conidia shielded from the sun (placed on the abaxial surface of the same leaves) died within a single day. Conidial viability was expressed in subsequent germination on an agar medium. Capilliconidial persistence was closely related to the daily air temperatures, expressed as cumulative day-degrees. Differences in relative humidity had no substantial effect on capilliconidial mortality. At daytime temperatures of ≤ 20°C, mortality after 24 h incubation was lowest (≤ 34%) and the persistence duration, longest (at least 120 h). Increases in daytime temperature up to 24°C for a few hours increased mortality (37–57% after 24 h incubation) and shortened the persistence duration (72–120 h). Exposure to 24–29°C during daytime greatly increased mortality (65–58% after 24 h) and further shortened the persistence duration (24–48 h). Daytime temperatures of > 29°C were lethal to all capilliconidia within 24 h. Temperature had a profound effect on capilliconidial persistence also under controlled environmental conditions. The significance of capiliiconidial persistence is discussed in relation to activity of the fungus in its natural environment.     

Reexamination of the immature hominid maxilla from Tangier,Morocco

Reexamination of the immature Upper Pleistocene hominid maxilla from Mugharet el-'Aliya (Tangier), Morocco is undertaken in light of new evidence on the growth and development of Upper Pleistocene hominids. Metric and qualitative comparisons were made with 17 immature Upper Pleistocene maxillae, and with a recent Homo sapiens sapiens sample. No unambiguous criteria for aligning the maxilla with Neandertals were found, although one character, the degree of maxillary flexion on the zygoma, strongly suggests that this child could be a representative of H. s. sapiens. The probable lack of a canine fossa in Mugharet el-'Aliya 1, the primary criterion used previously to align it with Neandertals, cannot be accurately extrapolated to its adult form from this juvenile. The present evidence suggests that it is inappropriate to refer to this fossil as “Neandertal-like” or as a North African “neandertaloid.” Thus, the Tangier maxilla should not be cited as evidence for the presence of Neandertal facial features in North Africa during the Upper Pleistocene. © 1993 Wiley-Liss, Inc.     

Postharvest disease control in mangoes using high humidity hot air and fungicide treatments

The disease control efficacy of quarantine heat treatments developed for fruit fly disinfestation in mangoes cv. Kensington Pride was evaluated in this study. Heat was applied using high humidity (>95% r.h.) hot air (HHHA) at temperatures ranging from 47–49°C. Anthracnose, caused by Colletotrichum gloeosporioides, was well controlled in mangoes heated to a core temperature of 46°C, 47°C or 48°C for 24, 10 or 8 min respectively, prior to ripening at 23°C for 16 days. Stem end rot, caused by Dothiorella dominicana and Lasiodiplodia theobromae, was not satisfactorily controlled by these treatments. In a subsequent experiment, fruit were immersed in a hot benomyl (0.5 g a.i. litre“¹ at 52°C for 5 min) or unheated prochloraz (0.25 ml a.i. litre¹ at 28°C for 30 s) dip before or after the application of HHHA (core temperature of 47°C for 10 min). During storage at 23°C for 15 days, the incidence of stem end rot was reduced by HHHA alone, although immersion in hot benomyl either before or after HHHA treatment greatly improved stem end rot control. HHHA treatment (core temperature of 46.5°C for 10 min) alone reduced the incidence of anthracnose in mangoes stored at 13°C for 14 days prior to ripening at 22°C, although a combination treatment consisting of HHHA and either hot benomyl or unheated prochloraz gave complete control of anthracnose under these storage conditions. HHHA treatment alone gave no control of stem end rot in mangoes stored at 13°C prior to ripening at 22°C. A supplementary hot benomyl treatment was required for acceptable control of this disease in cool-stored mangoes. The development of yellow skin colour in fruit was accelerated by HHHA treatment.