Growth,development and yield of pawpaw (Carica papaya L.) ‘Homestead selection’ in response to soil moisture stress

Summary The effects of four soil water potential regimes under greenhouse conditions on growth, development, and yield of ‘Homestead selection’ pawpaw were investigated. The objectives were to determine the critical soil water potential regime and the moisture sensitive stages of growth of pawpaw. Repeated cycles of stress to −6.0 bar soil water potential imposed as from vegetative phase prevented fruit formation by constantly causing flower abscission. The stressed plants were stunted in size. The −2.0 bar soil water potential value was considered the critical level for normal growth and reproductive development of pawpaw. The mid-vegetative, flowering and fruit enlargement phases were moisture sensitive.     

Modeling the geographic distribution of pawpaw (Asimina triloba [L.] Dunal) in a portion of its northern range limits,western New York State,USA

Pawpaw (Asimina triloba [L.] Dunal) is a small deciduous tree in eastern North America notable for its edible fruit. Its northern range extends into New York State (NYS) where it is listed as threatened, with only approximately 20 sites known to contain pawpaw. This research models the geographic distribution of pawpaw in western NYS (land area?=?27,263 km²) for four reasons: to understand factors shaping its distribution, to assess the degree to which it is protected, to locate potential introduction or reintroduction sites, and to locate potential sites with undiscovered pawpaw. This study uses an ensemble of small models (ESM) approach devised for modeling the distribution of rare species, which averages predictions from simple (i.e., bivariate) models weighted by model predictive performance. The ESM in this study, constructed from boosted regression tree (BRT) models, demonstrated a high ability to discern pawpaw presences from pseudo-absences. The area under the receiver operating characteristic curve (AUC) value was 0.986 when calculated using training data, and BRT models comprising the ESM exhibited AUC values calculated using cross-validation data as high as 0.957. The ESM suggests that pawpaw is found in the warmest (mean annual temperature?>?9.0 °C,) and driest (May–September precipitation?<?44 cm) areas of western NYS, and on mildly acidic (pH?=?5.5–7.0) and deep (>?110 cm) soils. Locations predicted to be suitable for pawpaw are overwhelmingly found on unprotected lands; forested areas in PAs with “high” or “highest” suitability for pawpaw only comprise 0.1–0.2% of the study area.

     

Decline viruses of pawpaw (Carica papaya L.) in East Africa

Three viruses or virus strains were isolated from pawpaw showing field decline symptoms in Tanzania and Kenya, where they are of wide occurrence. Each virus caused a distinct type of local lesion in Chenopodium quinoa; a fourth type of local lesion was induced when transmission was from a source containing two of the three viruses. When re-inoculated to pawpaw, alone or in combination, they caused stunting and decline symptoms similar to those observed in the field. Two were recovered from pawpaw pollen; none was transmitted through seed or from fruit to fruit, nor was any vector found. Purified preparations of the three viruses contained stiff rod-shaped particles 750 times 12 nm. Latex from pawpaw petiole and fruit totally inhibited sap transmission.     

Potential interactions between invasive woody shrubs and the gypsy moth (Lymantria dispar), an invasive insect herbivore

As the range of the invasive and highly polyphagous gypsy moth (Lymantria dispar) expands, it increasingly overlaps with forest areas that have been subject to invasion by non-native shrubs. We explored the potential for interactions between these co-occurring invasions through a gypsy moth feeding trial using the following three highly invasive, exotic shrubs: honeysuckle (Lonicera maackii), privet (Ligustrum sinense) and burning bush (Euonymus alatus). We compared these with two native shrubs: spicebush (Lindera benzoin) and pawpaw (Asimina triloba). We fed gypsy moth caterpillars foliage exclusively from one of the five shrubs and measured their relative consumptive rate (RCR), relative growth rate (RGR), and development time (DT). The RCR of gypsy moth was strongly influenced by the species of foliage (F = 31.9; P < 0.0001) with little or no consumption of honeysuckle and privet. Caterpillar RGR was influenced by the shrub species (F = 66.2; P < 0.0001), and those caterpillars fed spicebush, honeysuckle or privet lost weight over the course of the assay. Caterpillar DT was also significantly (F = 11.79, P < 0.0001) influenced by the shrub species and those fed honeysuckle, privet and spicebush died prior to molting. Overall, our data suggest that honeysuckle, privet, and spicebush could benefit (indirectly) from the invasion of gypsy moth, while burning bush and pawpaw could be negatively impacted due to direct effects (herbivory). Similarly, invading gypsy moth populations could be sustained on a shrub layer of burning bush and pawpaw in the event of canopy defoliation. Further field and laboratory analysis is needed to clarify herbivore resistance of invasive shrubs, and to investigate the potential interactions among co-occurring insect and plant invasions.     

The effects of Penicillium digitatum and Fusarium oxysporum rots on nutritional content of pawpaw (Carica papaya L.)

Investigations were carried out on the effects of Penicillium digitatum and Fusarium oxysporum on the nutritional value of pawpaw (Carica papaya). Decreases were observed in ash content, phosphorus, sodium, reducing sugars and ascorbic acid levels of fruits infected with P. digitatum, but increases in calcium and potassium content. In fruits infected by F. oxysporium, there were decreases in phosphorus, calcium, sodium ascorbic acid and reducing sugar levels; but the levels of ash content increased. The total protein level increased in the fruits infected with both fungi. These results revealed a reduction in fruit quality.     

Nutrient utilization profile of Saccharomyces Cerevisiae from palm wine in tropical fruit fermentation

The nutrient utilization pattern of Saccharomyces cerevisiae from palm wine was studied using tropical fruits as substrate. Starter cultures were prepared by growing 15-18 h old stock cultures of the yeast in successively larger bottles containing pasteurized fruit must. Microvinification, substrate utilization and assay of yeast activity were performed. Soluble solute (SS) content of the juices ranged from 10-18 Brix. Pinapple must had the highest SS content (18 Brix) while pawpaw had a low SS value of 10 Brix. These SS values were low compared to that of grape juice. The wines produced from the fruit must had percentage alcohol levels ranging from 10.6 to 12.6. Volatile activity ranged from 0.25 to 0.32 while crude protein values ranged from 0.58 to 0.68%. Palm wine yeast and all the other yeast strains fermented and utilized the fruit must for growth with specific growth rates ranging from 0.18 to 0.22. Sugar loss in Brix was gradual for all the fruit musts from 20.0-24.0 Brix to a range of 4.8 to 6.0 Brix. Pineapple was highly preferred for tropical wine making. Mango, cashew and pawpaw had equal ranking for commercial scale fermentation though more sugar will be needed to ameliorate cashew and pawpaw than mango juice. Palm wine yeast (OW-11) compared favourably with the other wine yeasts (CBS 8066 and ATCC 4126) both in nutrient utilization pattern and growth performance. A high degree of adaptability was observed in palm wine yeast recommands it for industrial wine production.     

Corynespora cassiicola leaf spot of pawpaw (Carica papaya L.) in Nigeria

Leaf spot of pawpaw is hereby reported for the first time in Nigeria. The symptom is characterized by a papery center surrounded by a yellow halo. The causal organism is Corynespora cassiicola. Ripe fruits and abaxial surfaces of the leaves were significantly more susceptible to infection than unripe fruits and adaxial surfaces of leaves. Growth and sporulation of the fungus on several media was investigated. The organism grew faster on malt-extract agar (MEA) derived media and slowest on potato-dextrose agar (PDA) supplemented with thiamine. Sporulation was highest on Czapek-dox agar (CDA) plus biotin and lowest on PDA and PDA + thiamine. Reasons for increased susceptibility of ripe fruit are discussed.This revised version was published online in October 2005 with corrections to the Cover Date.     

Observations on the biology and nutritive value of the African giant snail Archachatina marginata

Food habits, growth rate, reproductive performance, carcass characteristics and nutritive value of the giant snail were investigated in the field and with captive snails. Food consumed included fresh plant material, livestock faeces and dead animals. Clutch sizes varied from six to twelve and incubation periods from 30 to 45 days. Weight gains of young snails of average weight 20 g fed on diets of single plant species ranged from 18% on Talinum triangulare leaves to 200% on pawpaw fruit. Best growth was shown on leaves of cassava and cocoyam, grain chaff of maize and fruit of pawpaw. Dressing-out percentage of snails of 200 g weight was 37.8%. Nutrient composition of the edible portion compared closely with that of domestic livestock. Nitrogen-free extractive content was high at 5% and fat low at 1.3%. Mineral analysis revealed a high iron content of 12.2 mg/100 g in the edible carcass. The experiments showed that the snail could thrive in captivity on a variety of locally produced feeds, many of them rejected as waste products. It shows great promise as a domestic animal capable of being reared with negligible capital outlay.     

Pythium aphanidermatum root rot of pawpaw (Carica papaya L.) in Nigeria

Root rot of pawpaw (Carica papaya L.) reported in Nigeria is caused byPythium aphanidermatum which was consistently isolated from diseased plant parts and highly pothogenic. Out of 16 different media tested, it grew best on corn-meal-agar (CMA) and CMA supplemented with cellulose and sucrose. The highest number of oospores/ml was on CMA with average diameter of 19.9±0.1 µm. The symptom is characterized by dark brown rot of roots, absence of secondary roots and disintegration of internal tissue of the main root. These cause the progressive decline of the aerial parts of the tree untill it dies.     

利用基因芯片检测转基因作物

选用常用的两种报告基因、两种抗性基因、两种启动子序列和两种终止子序列为探针,将其PCR扩增产物用MicroGrid Ⅱ型全自动点样仪按矩阵排列点样于包埋有氨基的载玻片上,制备成转基因作物检测型基因芯片。利用该芯片对4种转基因水稻、木瓜、大豆、玉米进行检测,结果表明,该芯片能对转基因作物做出快速、准确的检测。 Abstract:Some selected available sequences of reporter genes,resistant genes,promoters and terminators are amplified by PCR for the probes of transgenic crop detection gene chip.These probes are arrayed at definite density and printed on the surface of amino-slides by bioRobot MicroGrid Ⅱ.Results showed that gene chip worked quickly and correctly,when transgenic rice,pawpaw,maize and soybean were applied.     

Plant-parasitic Nematode Problems in the Pacific Islands

The Pacific islands have a diverse range of food and cash crops with indigenous and introduced nematode problems. The staple food crops have serious nematode pests, such as Meloidogyne spp. on sweet potato, Hirschmanniella miticausa causing corm rot of taro, and Pratylenchus coffeae and Radopholus sp. producing tuber dry rot of yams. Bananas are infested with P. coffeae or R. similis, citrus with Tylenchulus semipenetrans, rice with Aphelenchoides besseyi, and ginger with Meloidogyne spp. and R. similis. Rotylenchulus reniformis, P. zeae, P. brachyurus, and Helicotylenchus spp. are important on all of these and other crops, such as sugarcane, passion fruit, pawpaw, and cassava. Meloidogyne spp. cause serious damage to local and introduced leaf and fruit vegetables and other crops, such as tobacco, sugarcane, pawpaw, black pepper, and pyrethrum. Many other plant-parasitic genera and species, some undescribed, occur in the Pacific, and there are many islands still to be investigated.     

Are insect frugivores always plant pests? The impact of fruit fly (Diptera: Tephritidae) larvae on host plant fitness

Herbivory is generally regarded as negatively impacting on host plant fitness. Frugivorous insects, which feed directly on plant reproductive tissues, are predicted to be particularly damaging to hosts. We tested this prediction with the fruit fly, Bactrocera tryoni, by recording the impact of larval feeding on two direct (seed number and germination) and two indirect (fruit decay rate and attraction/deterrence of vertebrate frugivores) measures of host plant fitness. Experiments were done in the laboratory, glasshouse and tropical rainforest. We found no negative impact of larval feeding on seed number or germination for three test plants: tomato, capsicum and eggplant. Further, larval feeding accelerated the initiation of decay and increased the final level of fruit decay in tomatoes, apples, pawpaw and pear, a result considered to be beneficial to the fruit. In rainforest studies, native rodents preferred infested apple and pears compared to uninfested control fruit; however, there were no differences observed between treatments for tomato and pawpaw. For our study fruits, these results demonstrate that fruit fly larval infestation has neutral or beneficial impacts on the host plant, an outcome which may be largely influenced by the physical properties of the host. These results may contribute to explaining why fruit flies have not evolved the same level of host specialization generally observed for other herbivore groups.     

The role of anthropogenic dispersal in shaping the distribution and genetic composition of a widespread North American tree species

Dispersal and colonization are among the most important ecological processes for species persistence as they allow species to track changing environmental conditions. During the last glacial maximum (LGM), many cold‐intolerant Northern Hemisphere plants retreated to southern glacial refugia. During subsequent warming periods, these species expanded their ranges northward. Interestingly, some tree species with limited seed dispersal migrated considerable distances after the LGM ~19,000 years before present (YBP). It has been hypothesized that indigenous peoples may have dispersed valued species, in some cases beyond the southern limits of the Laurentide Ice Sheet. To investigate this question, we employed a molecular genetics approach on a widespread North American understory tree species whose fruit was valued by indigenous peoples. Twenty putative anthropogenic (near pre‐Columbian habitations) and 62 wild populations of Asimina triloba (pawpaw), which produces the largest edible fruit of any North American tree, were genetically assayed with nine microsatellite loci. Putative anthropogenic populations were characterized by reduced genetic diversity and greater excess heterozygosity relative to wild populations. Anthropogenic populations in regions that were glaciated during the LGM had profiles consistent with founder effects and reduced gene flow, and shared rare alleles with wild populations hundreds of kilometers away (mean = 723 km). Some of the most compelling evidence for human‐mediated dispersal is that putative anthropogenic and wild populations sharing rare alleles were separated by significantly greater distances (mean = 695 km) than wild populations sharing rare alleles (mean = 607 km; p = .014). Collectively, the genetic data suggest that long‐distance dispersal played an important role in the distribution of pawpaw and is consistent with the hypothesized role of indigenous peoples.     

Cadmium,zinc, lead and copper inChironomus riparius (Meigen) larvae (Diptera,Chironomidae): uptake and effects

Cadmium, Zn, Pb and Cu uptake and effects in larvae ofChironomus riparius (Meigen) were studied in an integrated laboratory investigation, in which metal analyses in different instar stages, uptake kinetics and effects on development and growth were considered in three separate experiments.In short-term experiments with fourth instar larvae, it was demonstrated that only a minor portion of metals was adsorbed on the larval exoskeletons. No conclusive evidence on the uptake mechanism was found, but active uptake of trace metals seemed highly unlikely.In partial life cycle experiments, all four metals studied were readily accumulated in chironomid larvae. Uptake could be described satisfactorily utilizing a first-order one-compartment uptake model which incorporated growth. In all cases steady state conditions were approached and high uptake and elimination rate constants were estimated. Distinct differences between essential (Zn and Cu) and non-essential (Cd and Pb) metals were noted. Larval growth was significantly impaired upon exposure.Finally, long-term exposure experiments with low Cd concentrations (0.010 and 0.025 mg 1^{–1) resulted initially in growth impairment and high mortality in first instar stages, but surviving larvae restored growth and adults emerged even before control adults. In similar experiments with Zn (0.1 and 1.0 mg 1–1}), development of larvae was significantly retarded. High Zn concentrations in larvae were noted and almost no adult midges emerged.     

Anticipated and unexpected physiological effects of oligopeptides (glyprolines, ACTH (4-10) analogs, taftsin, and thyroliberin)

A short review of investigations resulting in determination of a new family of regulatory peptides (glyprolines) participating in modulation of hemostasis and protection of mucous membranes, obtaining of the ACTH4-10 new analogues which are potent neuroprotectors and nootrops, and revealing of unexpected biological activities of some other peptides (behavioural effects of tuftsin, lymph flow stimulation by thyroliberin, etc.). Further investigations into the functional peptide continuum is discussed.     

The osmaterial glands of the swallowtail butterfly Eurytides marcellus as a defence against natural enemies

ABSTRACT.

• 1 Natural enemies account for almost all mortality of zebra swallowtail caterpillars (Eurytides marcellus [Cramer]) feeding on pawpaw (Asimina spp.) in Florida.
• 2 The osmaterial glands of the third instar caterpillars reduce predation rates in the spring, but not later in the season.
• 3 The seasonal decline in effectiveness of osmateria in deterring natural enemies probably stems from a reduction in the importance of the predators that are repelled by osmateria.

     

Coenzyme Q(10) , endothelial function, and cardiovascular disease

Since the time a precise role of coenzyme Q(10) (CoQ(10) ) in myocardial bioenergetics was established, the involvement of CoQ in the pathophysiology of heart failure was hypothesized. This provided the rationale for numerous clinical trials of CoQ(10) as adjunctive treatment for heart failure. A mild hypotensive effect of CoQ was reported in the early years of clinical use of this compound. We review early human and animal studies on the vascular effects of CoQ. We then focus on endothelial dysfunction in type 2 diabetes and the possible impact on this condition of antioxidants and nutritional supplements, and in particular the therapeutic effects of CoQ. The effect of CoQ(10) on endothelial dysfunction in ischemic heart disease is also reviewed together with recent data highlighting that treatment with CoQ(10) increases extracellular SOD activity.     

The toxicity and sublethal effects of p,p'-DDT and dieldrin to Aglais urticae (L.) (Lepidoptera: Nymphalidae) and Chorthippus brunneus (Thunberg) (Saltatoria: Acrididae)

Single topical doses of pure p,p'-DDT and dieldrin (HEOD) were given to the last larval instars of Chorthippus brunneus and Aglais urticae bred under standardized conditions. The symptoms of acute toxicity followed the same pattern in all four insect-insecticide combinations, and there was a clear inverse correlation between the toxicity of absorbed insecticide and concentration of total lipid when dosed, both being dependent on age. It is probable that developmental changes in concentration of total lipid cause changes in resistance to the lipophilic and hydrophobic organochlorine insecticides. These results illustrate the importance of using the amount of insecticide absorbed rather than the amount applied for the interpretation of data. Unabsorbed insecticide was estimated by methanol rinses; there was some evidence that these remove a small proportion of absorbed insecticide from A. urticae, but not from C. brunneus. Sublethal effects tend to occur at times of lipid mobilization. There was considerable correlation between insecticide persistence and the occurrence of sublethal effects. Both species convert DDT to DDE readily, although only A. urticae retains DDE for long. No obvious effects were detected in C. brunneus. The only effect in A. urticae was retarded pupation when a large dose was applied fairly near the time of pupation. Dieldrin was more toxic and persistent, and caused latent toxicity, deformation of adults, sterility, and hyperactivity of adults in A. urticae, although there were no apparent effects on C. brunneus except for a possible decrease in the time to moult. Neither insecticide affected water uptake in C. brunneus eggs, and development continued normally up to hatch. The hatched nymphs were unaffected by DDT, most of which was in the egg membranes, and the nymphs rapidly metabolized the rest to DDE. Dieldrin did kill nymphs at eclosion. There was no evidence of effects on the genetic constitution of future generations, but the survival and reproductive abilities of individuals can obviously be affected. I conclude, from two measures of the amount of insecticide acquired by A. urticae in the field, and from the amount required to produce sublethal effects, that A. urticae is probably, with present levels of contamination, unaffected by DDT or dieldrin outside sprayed areas, but more information is needed on other possible effects, and on amounts found in wild specimens. I discuss how far this conclusion applies to other insect species.     

Cytogenetic effects of combined radioactive (137Cs) and chemical (Cd, Pb, and 2,4-D herbicide) contamination on spring barley intercalar meristem cells

The frequency of cytogenetic effects in spring barley intercalar meristem cells was studied in the presence of a range of different stressors. There was a non-linear dependence on the concentrations of 137Cs, Cd, Pb, and dichlorophenoxyacetic acid (2,4-D) herbicide contamination in the exposure ranges used. The frequency of cytogenetic effects increased at the lower concentrations of the pollutants more rapidly than at the higher concentrations. Contamination of the soil by lead at a concentration that meets the current standards for permissible content in soil, and by 2,4-D herbicide at the application levels recommended for agricultural use resulted in a significant increase in aberrant cell frequency. In these cases, the extent of the observed cytogenetic effects was comparable with the effect induced by a 137Cs soil contamination of 49.2 kBq/kg, a level that exceeds by 10-fold the maximum level permitted in radionuclide-contaminated areas where people are resident. In most cases, the experimentally observed combined effects of the pollutants studied differed from those expected from an additive hypothesis. When combined with 137Cs contamination, antagonistic effects became increasingly stronger when the second stressor was changed from cadmium to lead, and then to the herbicide, as measured both by tests of the 'frequency of aberrant cells' and the 'aberrations per cell'. Data from this study and previous reported literature suggest that synergistic increases in cytogenetic effects can be induced by the simultaneous influence of several stressors even at low intensities. This indicates that there is a capability for mutual intensification of the effects of environmental factors that actually occur in situations of low-level exposure.     

Synthesis, structural properties and insulin-enhancing potential of bis(quercetinato)oxovanadium(IV) conjugate

An oxovanadium complex of quercetin (2), exhibits highly potent insulin-enhancing activity in streptozotocin-induced diabetic mice. It also mimics mitogenic potential of insulin as evaluated by [H(3)]thymidine uptake assay making an effective, orally active insulin-enhancing agent for the treatment of both type 1 and type 2 diabetes without any noticeable toxic effects.