Distribution and population dynamics of Porphyra (Bangiales, Rhodophyta) in the southern Western Cape, South Africa

Although Porphyra is commercially farmed in many countries, in South Africa only small harvests of wild populations for sale as nori have been carried out. The discovery that Porphyra improves growth of South African abalone (Haliotis midae) farmed inland-based tanks has led to increased pressure to harvest wild populations. This paper reports on a survey of the distribution and seasonality of Porphyra in the southern Western Cape. Porphyrawas present at all sites surveyed, and showed considerable temporal variation. A significant amount of the Porphyra present is in reserves and therefore protected from harvesting. Close rexamination of one site revealed seasonal populations of Porphyra that occupied different niches dependent on season. Recruitment peaked in spring and autumn, leading to dense summer and winter populations. Summer populations generally grew lower in the eulittoral than winter populations. No pattern in the mortality of larger thalli wasde tected, though sporeling mortality was high following recruitment peaks. Although it seems that most sites in the southern Western Cape are suitable for harvesting, the taxonomy of the genus in the region urgently needs revision if populations are to be appropriately managed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Studying stress responses in the post-genomic era: its ecological and evolutionary role

Most investigations on the effects of and responses to stress exposures have been performed on a limited number of model organisms in the laboratory. Here much progress has been made in terms of identifying and describing beneficial and detrimental effects of stress, responses to stress and the mechanisms behind stress tolerance. However, to gain further understanding of which genes are involved in stress resistance and how the responses are regulated from an ecological and evolutionary perspective there is a need to combine studies on multiple levels of biological organization from DNA to phenotypes. Furthermore, we emphasize the importance of studying ecologically relevant traits and natural or semi-natural conditions to verify whether the results obtained are representative of the ecological and evolutionary processes in the field. Here, we will review what we currently know about thermal adaptation and the role of different stress responses to thermal challenges in insects, particularly Drosophila. Furthermore, we address some key questions that require future attention.     

Habitat diversity and adaptation to environmental stress in encysted embryos of the crustacean<Emphasis Type="Italic">Artemia</Emphasis>

Encysted embryos (cysts) of the brine shrimp,Artemia, provide excellent opportunities for the study of biochemical and biophysical adaptation to extremes of environmental stress in animals. Among other virtues, this organism is found in a wide variety of hypersaline habitats, ranging from deserts, to tropics, to mountains. One adaptation implicated in the ecological success ofArtemia is p26, a small heat shock protein that previous evidence indicates plays the role of a molecular chaperone in these embryos. We add to that evidence here. We summarize recently published work on thermal tolerance and stress protein levels in embryos from the San Francisco Bay (SFB) of California inoculated into experimental ponds in southern Vietnam where water temperatures are much higher. New results on the relative contents of three stress proteins (hsp70, artemin and p26) will be presented along with data on cysts of A.tibetiana collected from the high plateau of Tibet about 4.5 km above sea level. Unpublished results on the stress protein artemin are discussed briefly in the context of this paper, and its potential role as an RNA chaperone. Interestingly, we show that the substantial tolerance ofA. franciscana embryos to ultraviolet (UV) light does not seem to result from intracellular biochemistry but, rather, from their surrounding thick shell, a biophysical adaptation of considerable importance since these embryos receive heavy doses of UV in nature.     

Long-proboscid fly pollination of two orchids in the Cape Drakensberg mountains,South Africa

Large hovering flies with elongated nectar-feeding mouthparts play an important role in the pollination of South African plants. Here we describe and illustrate the pollination of two long-spurred orchids —Disa oreophila H. Bolus subsp.erecta Linder andBrownleea macroceras Sond. — by the long-proboscid flyProsoeca ganglbaueri Lichtwardt (Nemestrinidae).     

Studies on the life history of the population of an evergreen herb,Pyrola japonica,on the forest floor in a warm temperate region

Photosynthetic and respiratory activities and gross production in relation to temperature conditions were investigated in the population of an evergreen herb,Pyrola japonica, growing on the floor of a deciduous forest in the warm temperate region of central Japan. Analysis of the temperature-photosynthesis relationship ofP. japonica leaves during the growing season indicated distinct seasonal changes in the temperature optimum for photosynthesis. This population was found to be acclimatable to ambient air temperatures exceeding 15C, but this acclimation became less pronounced under thermal conditions below 15 C. This plant possessed narrow photosynthetic optima in the warm season but wide optima in the cold season. The shape of the temperature-respiration curve did not vary significantly with the months except for April. The Q₁₀ for respiration between 10 C and 20 C was calculated to be 1.93–2.65. Annual dry matter loss associated with respiration was estimated to amount to 159.1 g d.w.m⁻² based on the measurements of the seasonal changes in the respiratory activity of each organ. Gross production of this population was estimated to be 219.3 g d.w.m⁻² year⁻¹ as the sum total of the net production (60.2 g d.w.m⁻²year⁻¹) and the respiration. Monthly gross production was high in the early growing season, and low and stable in winter.     

Studies on the life history of an evergreen herb,Pyrola japonica,population on a forest floor in a warm temperate region

The life history and matter economy were studied on an evergreen herb,Pyrola japonica Klenze, population growing on the floor of a deciduous forest in a warm temperate region, central Japan. Seasonal changes in standing crop, bulk density and reserve substance of each organ and in leaf area were investigated over a year. Monthly and annual net production of the population were estimated based on the growth in dry weight and the seasonal dynamics of reserve substance. Seasonal peak value of the monthly net production was 16.7 g d.w.m⁻² in May. The annual net production was estimated to be 60.2 g d.w.m⁻². Two phases were recognized in the annual pattern of development and matter economy of this plant. Phase I, from April to June, was characterized by the development of aboveground vegetative organs and the consumption of reserve substance rrom old organs. Phase II, from July to March, was characterized by the development of reproductive and underground organs, and the accumulation of reserve substance. Phase II was further divided into two sub-phases according to the behavior of the reserve substance and the rate of net production. The production process of the population was compared with those of other evergreen herbs growing on the forest floor in warm temperate regions.     

Seasonal food habits of a sika deer population in the warm temperate forest of the westernmost part of Honshu, Japan

The rumen contents of 63 sika deer (Cervus nippon Temminck) shot in the westernmost part of Honshu were analyzed by the point-frame method. The rumen contents were dominated by forbs and the majority of these were evergreen monocotyledonous plants, probably Ophiopogon spp. Evergreen browse leaves (woody leaves), such as Eurya japonica Thunb., Ilex crenata Thunb. and Trachelospermum asiaticum Nakai, were also important, constituting 20–40% of the rumen contents. Other categories accounted for only small proportions, although in summer, graminoids increased but twigs and bark decreased in importance and in fall and winter, fruits and seeds increased in importance. The diet of the deer was characterized by high-quality foods even in winter and by a stability or less-pronounced seasonality throughout the year than found in the northern deer. These results were compared with those from other populations, including a northern sika deer population in Japan.     

The role of herbivores in the collapse of the Gracilaria resource at Saldanha Bay,South Africa

At Saldanha bay on the west coast of South Africa, annual yields of beach-cast Gracilaria often exceeded 1000 metric tons, until the construction of an ore jetty and breakwater in 1974. Yields were then drastically reduced, recovered to 429 tons in 1988, then fell to zero. Diving surveys revealed a steady decline in the biomass of the remaining beds from 50 t in April to less than 1 t in August 1989. The presence of large numbers of herbivores suggested that grazing was the cause. This hypothesis was tested by experimental exclusions of fish and/or invertebrate herbivores (keyhole limpets and sea urchins). Results show that grazing by the fish in shallow water and the keyhole limpets and urchins in deep water prevented recovery of the resource and may have caused the initial decline.     

昆明桃园果蝇寄生蜂种类及其种群动态

【目的】为控制果蝇类害虫危害,需掌握昆明桃园内果蝇寄生蜂的种类及种群消长动态。【方法】2014年4—10月在云南昆明小河乡(25°10′55.07″N,102°47′52.51″E,海拔2200 m)桃树果园,利用香蕉、诱盒收集桃园内果蝇天敌昆虫寄生蜂并进行分类鉴定,对其种群动态进行监测。【结果】共收集到6种果蝇寄生蜂,762只。经过鉴定分别为茧蜂科的Asobara brevicauda和Asobara mesocauda、环腹瘿蜂科的Leptopilina japonica、瘿蜂科的Ganaspis brasiliensis、锤角细蜂科的Trichopria drosophilae、金小蜂科的Pachycrepoideus vindemiae。其中A.mesocauda(29.40%)、G.brasiliensis(17.85%)、T.drosophilae(47.77%) 3种寄生蜂的发生数量相对较多,且不同寄生蜂的种群动态随着季节呈现不同的变化。【结论】结合桃园内果蝇的种群动态,初步筛选出果蝇的优势天敌为瘿蜂科G.brasiliensis和锤角细蜂科T.drosophilae,并将对其的保护利用开展进一步研究。     

Heat shock protein of the Hsp70 family in the euryhaline cilate Paramecium nephridiatum and its role in adaptation to salinity changes

The level of the Hsp70 heat shock protein was studied in the cells of euryhaline ciliates Paramecium nephridiatum after environmental salinity changes. Two types of treatment were used: “shock” and “adaptation.” In the former case the ciliates were placed for 1 h into medium with stress salinity, and subsequently returned for 2 h to the medium they were acclimated to. In the latter case the ciliates were placed for 3 h into the medium with the stress level of salinity. The ciliates acclimated to fresh water (0‰ salinity) were shown to have a higher constitutive level of Hsp70 than those acclimated to 10‰. Transfer of the protists from fresh water to medium with 10‰ salinity (the shock medium) did not increase Hsp70 synthesis, whereas the return transfer resulted in induction of Hsp70 in the cells. In both directions of salinity change, “adaptation” led to induction of Hsp70. The obtained results support the hypothesis that salinity of 10‰ is less harmful for the eurihaline ciliate P. nephridiatum, than fresh water is. We also presume that the ability of euryhaline ciliates to survive in a wide salinity spectrum might be determined by the higher constitutive level of their Hsp70 in comparison with that of stenohaline representatives of the same genus.     

Biological control of an alien tree, Acacia cyclops, in South Africa: impact and dispersal of a seed-feeding weevil, Melanterius servulus

Several Australian Acacia species have become highly invasive in a number of ecologically sensitive areas of South Africa. Many have useful attributes that, to an extent, have hampered biocontrol efforts by restricting potential agents to those reducing seed production whilst not affecting vegetative growth. The outcome of the introduction of a seed-feeding weevil, Melanterius servulus, against Acacia cyclops in 1994, was assessed by investigating the plant’s reproductive phenology, as well as levels of damage caused by the beetles. The study provided essential information on host/agent interactions and, on the build up and spread of populations of the agent. Seed damage is commonly as high as 90% (exceptionally it reaches 100%), and dispersal rates of the beetles on average is almost 2 km per year. The consistently high levels of seed damage achieved hold promise for the future of the program, however, its ultimate success will be further enhanced through the integration of biological control with other manual clearing operations that are currently employed on a large scale in South Africa.     

A quick method to estimate the T-DNA copy number in transgenic plants at an early stage after transformation,using inverse PCR

Agrobacterium-mediated transformation of plants is known to result in transgenic plants with a variable number of integrated T-DNA copies [1, 2, 3, 7]. Our aim was to obtain transgenic tobacco plants containing one integrated T-DNA copy per genome. Therefore, a quick method was developed to estimate the T-DNA copy number of young transgenic plantlets within 10 weeks after transformation. Inverse polymerase chain reaction (IPCR) was used to amplify junction fragments, i.e. plant genomic DNA sequences flanking the known T-DNA sequences [5].     

闽江口秋茄凋落叶分解碳氮磷元素动态特征与水解酶活性

凋落物水解酶活性和环境要素对凋落物的分解有重要影响。为研究秋茄凋落叶分解过程中碳(C)、氮(N)、磷(P)元素动态特征及水解酶活性变化,采用凋落物分解袋法,以闽江口粗芦岛红树林湿地20年生秋茄(Kandelia obovata)为研究对象,探讨秋茄凋落叶在秋茄(主场)和互花米草(Spartina alterniflora Loisel.)(客场)生境分解的差异。结果表明:①整个分解期间,主场生境秋茄凋落叶累计质量损失率显著高于客场生境(P0.05),两生境下累计质量损失率和分解速率随分解时间变化差异性明显(P0.01)。主客场生境对比下,凋落叶C、N、P含量及其化学计量比没有显著性差异(P0.05),但均随分解时间推移发生显著性变化(P0.01)。②凋落物累计质量损失率与TC含量、C/N、酸性磷酸酶(AP)活性呈显著负相关关系(P0.01)、与TN显著正相关(P0.01),分解速率与TP呈显著正相关关系(P0.01)。③AP活性与凋落物C、N、P含量及C/N、C/P显著相关(P0.05),与土壤温度呈显著正相关关系(P0.01)。β-葡萄糖苷酶(βG)和β-N-乙酰氨基葡萄糖苷酶(NAG)均与N/P呈显著正相关关系(P0.01)、与土壤电导率负相关关系明显(P0.05),纤维素水解酶(CBH)与TC呈显著正相关关系(P0.05)。说明秋茄凋落叶的分解与部分水解酶活性和自身养分含量相关,并受到土壤环境因子的影响较大;凋落物分解过程中,水解酶活性会受到分解底物和土壤环境因子环境限制。     

Structure and dynamics of an invasive population of the red swamp crayfish (<Emphasis Type="Italic">Procambarus clarkii</Emphasis>) in a Mediterranean wetland

This study analyzes the population structure and dynamics of an invasive population of Procambarus clarkii (Girard, 1852) in a Mediterranean wetland using the Bhattacharya’s and Von Bertallanfy’s analytical methods. The main purpose was to collect biological data necessary for the management of this nuisance species. A maximum of five age classes were identified for both sexes, three of which being composed of a few or zero individuals. Age classes were classified into two subgroups––spring (SpL) and summer (SuL) lines––on the basis of the different hatching periods. Individuals of SpL showed a faster growth rate and reached a larger body size than those belonging to SuL, probably because they were able to grow for a longer time. No between-sex differences were found in growth patterns except for the asymptotic length (L_∞), which was reached faster by the females. Other population properties were analyzed, such as a high mortality rate, a maximum longevity of 4 years, and a low mean life-time (<12 months). Finally, a relatively small fraction of individuals seemed to survive after the first reproductive peak in spring. Consequently, the structure and dynamics of the study population seem to reveal its stability and spreading potential, as a confirmation of the invasiveness of P. clarkii in Mediterranean wetlands. Handling editor: P. Viaroli     

Variations in the morphological characteristics ofTriops granarius (Lucas) (Crustacea:Notostraca) in a pan system at Bain's Vlei,South Africa

The morphological characteristics of a population ofTriops granarius in a system of small pans were examined during inundations of one season. Considerable variation was found in a number of characteristics. Differences in gender other than those of the reproductive organs were also significant, but diagnostic characteristics remained stable.     

<Emphasis Type="Italic">Spartina maritima</Emphasis> influence on the dynamics of the phosphorus sedimentary cycle in a warm temperate estuary (Mondego estuary,Portugal)

During the last decades the Mondego estuary has been under severe ecological stress mainly caused by eutrophication. In this salt march system, Spartina maritima covers about 10.5 ha of the intertidal areas. The objective of the present study was to evaluate the effect of Spartina maritima marshes on the dynamics of phosphorus (P) binding in the surface sediment. We compare phosphate and oxygen fluxes, P-adsorption capacity, phosphate concentrations and total amount, and the extractable P forms in the upper 20 cm of sediment in vegetated sediment with adjacent mudflats without vegetation. Sediment pore-water profiles followed a clear trend, with lower P concentrations in more superficial layers, and increasing with depth. The vegetated mudflats presented lower concentrations of dissolved inorganic phosphorus than adjacent bare bottom mudflats, lower phosphate total amount, as well as higher P-adsorption capacity. Results from the extraction procedure show that the superficial layers are the most important for estuarine phosphorus dynamics, since maximum concentrations of labile P pools are present here. In contrast, higher proportions of refractory P pool are found in deeper layers. Spartina marsh sediments had less total P, less iron bound P, and less exchangeable P than adjacent bare bottom mudflats. Also the pool of loosely sorbed P is lower in the Spartina marsh. Phosphate regeneration from the sediment to the overlying water was only 11.8 kg ha⁻¹ year⁻¹ in vegetated sediment while 25.8 kg ha⁻¹ year⁻¹ in the bare mud flat. Plant uptake for growth combined with an enhanced P-adsorption capacity of the sediment, may explain these differences. Therefore, Spartina marshes are very important agents in the sedimentary P cycle worldwide, and can be considered a useful management tool in estuarine ecosystem recovery efforts.     

The fixed plot survey method for determining the host range of the flowerbud-feeding weevil Dicomada rufa, a candidate for the biological control of Hakea sericea in South Africa

The hakea bud weevil, Dicomada rufa (Curculionidae), is a promising candidate for the biological control of the weed Hakea sericea (Proteaceae) in South Africa. Because D. rufa could not be successfully cultured on potted plants in quarantine, most of theconventional methods for host range determination were not suitable. A type of open-field testing method, the fixed plot survey method, was developed to show that D. rufa is host specific to H. sericea. The trial was conducted in three 1–2 ha plots at three localities in New SouthWales, Australia, involving 41 test plantspecies. This result was combined with otherconventional considerations to apply for therelease of D. rufa in South Africa. Theseincluded a multiple choice feeding trial inquarantine in South Africa, during which 10test species from seven genera of South AfricanProteaceae were not accepted for feeding. AllSouth African Proteaceae, except Brabejumstellatifolium, are phylogenetically distinctfrom H. sericea. Also, there are norecords of D. rufa interacting withcommercially important plants in Australia,including commercially cultivated South AfricanProteaceae. Dicomada rufa adult andlarval feeding destroys buds, flowers, smallfruits and succulent shoots. It is expectedthat this damage will supplement that of thetwo seed-feeding biological control agentsalready established in South Africa and furtherreduce the reproductive potential of the weed,particularly that of young plants regeneratingafter fires. Without compromising safety, thefixed plot survey method may also contribute toreducing the time and cost normally associatedwith conventional host specificity testing.     

H9724, a Monoclonal Antibody to Borrelia burgdorferi's Flagellin, Binds to Heat Shock Protein 60 (HSP60) Within Live Neuroblastoma Cells: A Potential Role for HSP60 in Peptide Hormone Signaling and in an Autoimmune Pathogenesis of the Neuropathy of Lyme Disease

Although Borrelia burgdorferi, the causative agent of Lyme disease, is found at the site of many disease manifestations, local infection may not explain all its features. B. burgdorferi's flagellin cross-reacts with a component of human peripheral nerve axon, previously identified as heat shock protein 60 (HSP60). The cross-reacting epitopes are bound by a monoclonal antibody to B. burgdorferi's flagellin, H9724. Addition of H9724 to neuroblastoma cell cultures blocks in vitro spontaneous and peptide growth-factor–stimulated neuritogenesis. Withdrawal of H9724 allows return to normal growth and differentiation. Using electron microscopy, immunoprecipitation and immunoblotting, and FACS analysis we sought to identify the site of binding of H9724, with the starting hypotheses that the binding was intracellular and not identical to the binding site of II-13, a monoclonal anti-HSP60 antibody. The current studies show that H9724 binds to an intracellular target in cultured cells with negligible, if any, surface binding. We previously showed that sera from patients with neurological manifestations of Lyme disease bound to human axons in a pattern identical to H9724's binding; these same sera also bind to an intracellular neuroblastoma cell target. II-13 binds to a different HSP60 epitope than H9724; II-13 does not modify cellular function in vitro. As predicted, II-13 bound to mitochondria, in a pattern of cellular binding very different from H9724, which bound in a scattered cytoplasmic, nonorganelle-related pattern. H9724's effect is the first evidence that HSP60 may play a role in peptide-hormone–receptor function and demonstrates the modulatory potential of a monoclonal antibody on living cells.     

A seminal study of the dynamics of a mudskipper (Periophthalmus papilio) population in the Cross River,Nigeria

A seminal study was conducted in which the population dynamics (growth, mortality and recruitment) of the mudskipper (Periophthalmus papilio) in the Cross River, Nigeria, was elucidated for the first time using length frequency data and the ELEFAN software. The allometric relationship was: Weight=0.012(Length)^2.940, n=415, r²=0.939, P <0.0005. The seasonalized Von Bertalanffy growth parameters were L=19.39 cm, K=0.51 y^–1, C=0.3, and WP=0.4. The instantaneous total mortality coefficient Z was 2.208 y^–1 while the instantaneous natural mortality coefficient was 1.341 y^–1. The instantaneous fishing mortality coefficient of 0.867 y^–1 yielded the expectedly low exploitation rate E of 0.393. Our estimate shows that the species could reach an average maximum life span of about 6 years in the Cross River system. These results are used in quantitative elucidation of the state of exploitation of the population and will serve as input for the proper and scientific management of the fish resource.Alfred Wegener Institute Contribution nr. 1090.     

Tolerance of Borya nitida,a poikilohydrous angiosperm,to heat,cold and high-light stress in the hydrated state

Borya nitida Labill., a plant able to colonize rock outcrops and shallow sands in areas of high incident solar radiation in Western Australia, was examined for its tolerance to extremes of temperature, and to intense visible radiation. Stress injury to the leaves from heat, chilling or photoinhibitory light was followed by the decrease in in-vivo variable chlorophyll fluorescence. Heat injury was also ascertained by an increase in the constant fluorescence. Borya nitida leaves were extremely heat tolerant when heated at 1° C min^-1. In-vivo variable chlorophyll fluorescence was detectable up to 55° C, several degrees higher than either maize or barley which are, respectively, adapted to warm and cool climates. An increase in constant fluorescence occurred above 50° C in B. nitida. This compares with values in the literature of 48–49° C for three desert plants from Death Valley, California, and 44–48° C for ten species of tropical plants. Unlike the Death-Valley plants, the high degree of heat tolerance found in B. nitida did not require prior acclimation by growth at high temperatures. Borya nitida was also tolerant of a chilling temperature of 0° C. Plants grown at a low photon fluence rate (120 mol m^-2s^-1) were irreversibly photoinhibited by light at 650 mol m^-2s^-1. Plants grown in sunlight resisted photoinhibition; however, the capacity to withstand photoinhibition was no greater than that of plants from less extreme environments.