THE REDUCING GROUPS OF PROTEINS

1. Intact, unhydrolyzed proteins possess in addition to SH groups other reducing groups which can be oxidized by ferricyanide. 2. The activity of these reducing groups, like that of SH groups, is enhanced by denaturation of the protein and by increase of pH and temperature. 3. These groups differ from SH groups in the manner in which their activity is dependent on concentration of ferricyanide and time of contact with ferricyanide. 4. The activity of these groups is increased if protein SH groups are present. 5. The number and activity of these groups varies from protein to protein. 6. These groups are probably contained in the tyrosine and tryptophane components of proteins. 7. The significance of these reducing groups for an understanding of protein denaturation and the reducing properties of tissues is indicated.     

The effects of familiarity and social hierarchy on group membership decisions in a social fish

Members of animal groups face a trade-off between the benefits of remaining with a familiar group and the potential benefits of dispersing into a new group. Here, we examined the group membership decisions of Neolamprologus pulcher, a group-living cichlid. We found that subordinate helpers showed a preference for joining familiar groups, but when choosing between two unfamiliar groups, helpers did not preferentially join groups that maximized their social rank. Rather, helpers preferred groups containing larger, more dominant individuals, despite receiving significantly more aggression within these groups, possibly owing to increased protection from predation in such groups. These results suggest a complex decision process in N. pulcher when choosing among groups, dependent not only on familiarity but also on the social and life-history consequences of joining new groups.     

Effects of Supplementary Feeding on the Breeding Ecology of the Buff-Throated Partridge in a Tibetan Sacred Site,China

Our goal was to document effects of year-round supplemental feeding on breeding ecology of the Buff-throated Partridge, Tetraophasis szechenyii, within a Tibetan sacred site. We evaluated effects of supplemental feeding used as religious/cultural practices which could potentially aid conservation of endangered phasianids. We compared fed breeding groups to neighboring nonfed groups. Fed groups initiated first clutches significantly earlier than nonfed groups. Earlier laying groups within fed and nonfed groups showed significantly lower hatching rates than later groups; however, fed groups showed significantly higher hatching rates than nonfed groups laying in the same period. Earlier laying increased opportunities to renest. All six fed groups with clutch failures renested compared to only one of five nonfed groups with clutch failures. Fed female breeders showed significantly greater investment in their young with larger clutches and larger eggs, which likely increased survivability of early hatchlings. We observed no predation on birds at feeding sites and recorded only four cases of predation on incubating females, which showed no detectable difference between fed and nonfed groups. Ground-nesting birds typically face high risks of predation. Ten of the 48 groups nested in trees, which occurs in few phasianid species. Tree nests showed significantly higher hatching rates compared to ground nests; however, we found no significant difference in tree nesting between fed and nonfed groups. This partridge is one of four gallinaceous species with cooperative breeding. Breeding groups with helpers had significantly greater reproductive success than single pairs, and fed female breeders with helpers laid bigger eggs than single pairs. Comparing annual reproductive output per group, fed groups not only produced significantly more independent young (≥150 days post-hatching), their young hatched significantly earlier, which likely have greater reproductive value over later hatched young of nonfed groups. Supplemental feeding year-round is likely what enabled the successes of the fed partridges.     

Changes in the composition of ionogenic groups of the wall of the lily pollen grain during germination

Changes in the composition of ionogenic groups of the polymeric matrix of the cell walls of lily (Lilium longiflorum Thunb.) pollen grains were studied during its activation at the early stages of pollen germination. In the cell walls isolated from nonactivated and activated pollen grains, four types of ionogenic groups were identified: amino groups, carboxylic groups of uronic acids, phenolic OH-groups. and groups with pK_a 7–8. During the early stages of germination, ionization constants of each type groups remained unchanged, but the quantitative composition of ionogenic groups in the intine changed. In this matrix, a decrease in the content of phenolic groups and demethylated carboxylic groups of uronic acids was detected. It is supposed that, at early stages of germination, the intine loses some part of acid pectins and some phenolic compounds.     

Vigilance in Single- and Mixed-Species Groups of Tamarins (Saguinus labiatus and Saguinus fuscicollis)

By forming larger sizes of groups, individuals benefit from a decrease in vigilance, but the collective vigilance of the group as a whole is not compromised. We examined whether this group size effect is apparent in mixed-species groups of red-bellied tamarins (S. labiatus) and saddleback tamarins (S. fuscicollis) which form stable and permanent associations in the wild. We studied general vigilance and responses to hidden threatening stimuli in five captive groups of each species, while they were housed in single- and mixed-species groups. For vigilance, the individual rate was lower in the larger mixed-species groups than in the smaller single-species groups. In addition, the amount of time when at least one individual was vigilant was higher in mixed-species groups. This suggests that the tamarins alter their vigilance behavior in the presence of the other species. In response to hidden threats, both species performed brief vigilance checks and frequencies of checking did not differ in single- and mixed-species groups. However, both species had a significant reduction in the mean duration per check, and there was a reduced total amount of time spent vigilance checking in the mixed-species groups compared to the single-species groups, demonstrating the group size effect. Overall the mixed-species groups had a higher number and mean duration of checking than the smaller single-species groups. Given that the two species share a common set of predators, and respond to each other's alarm calls, these findings provide strong evidence that individuals of both tamarin species may be able to benefit from forming mixed-species groups via improved vigilance and monitoring of threats.     

Clique formation of super-sister honeybee workers (<Emphasis Type="Italic">Apis mellifera</Emphasis>) in experimental groups

Summary One day old honeybee workers (Apis mellifera) were observed in small experimental groups (10 workers per group). These groups were either composed of offspring workers of singly inseminated queens (super-sister groups) or multiply inseminated queens (mixed groups). The groups thus consisted of either super-sisters or a mix of super- and halfsisters. The positions of the individually labelled workers were observed with infrared sensitive video equipment over a 24 h period and analysed with digital image analysis. The spatial distribution of workers in super-sister and mixed groups differed significantly. The distance between super-sister workers was significantly less than in mixed groups (n = 339; p < 0.01). Also the distance of the workers from the group centre was significantly less in super-sister groups as compared to mixed groups (n = 3440, p<0.05). The super-sisters thus formed tighter groups than the groups including half-sisters. A genotypic analysis of the mixed groups with microsatellite DNA markers revealed that workers were significantly more frequently observed next to a super-sister rather than a half-sister (p < 0.001). Irrespective whether this results from kin recognition or not, we expect clique formation to be an important factor for the development of task specialisation among worker bees.Received 26 August 2002; revised 22 April 2003; accepted 25 July 2003.     

黄腹角雉生态群养技术研究

模拟黄腹角雉野外生存环境和自然种群结构,采用较大空间散放与多个体群养相结合的方法进行饲养试验,其笼养繁殖性能比对照组传统对养方式显著提高．通过两年来的试验研究,结果表明：试验组平均产卵量为8．5枚,卵受精率为82．6％,受精卵孵化率为88．7％;对照组平均产卵量5．7枚,卵受精率50．3％,受精卵孵化率72．4％,试验组明显高于对照组．同时对两组间的卵重、卵形、产卵期进行了测定,无显著差异。     

Activity rhythm and the ranging of a solitary male mountain gorilla (Gorilla gorilla beringei)

To clarify the advantages of solitary life in gorilla males, a lone silverback mountain gorilla (Gorilla gorilla beringei) was studied for nine months in the natural habitat of the Virunga volcanoes. While the time budget for each activity and daily activity cycle were similar to those of groups, his daily journey distance and ranging patterns differed from those of groups. His movements were little influenced by the distribution and abundance of foods, which strongly influence the movements of groups. He notably increased his day journey distances when he encountered neighboring groups. He persistently followed the groups for days and went out of his usual range area. These encounters shifted his monthly range from his natal group's range to that of other groups. When the silverbacks of the encountered groups noticed his presence, they usually gave hoots and chest-beats and sometimes fought violently with him, while females and immatures did not show positive responses towards him. Lone males could have more chance to contact females and to lure them away from their groups than silverbacks within groups. The lone male stage, accompanied by frequent contacts with different groups, probably provides maturing males with useful knowledge of neighboring groups and areas.     

东方田鼠社群气味对家族群成员个体觅食行为的影响

东方田鼠家族群成员个体的觅食行为是否因食物斑块存有家族群自身及非亲缘家族群气味而发生变异,进而影响其摄入率。在新鲜马唐叶片构建的均质密集食物斑块上,分别配置家族群自身巢垫物及非亲缘家族群巢垫物作为社群气味,测定东方田鼠家族群在食物斑块觅食时,其成员个体觅食行为的序列过程及参数,检验家族群自身气味及非亲缘家族群气味对成员个体觅食行为的影响。结果表明,家族群自身气味能显著地缩短本群成员个体的觅食决定时间,通过减少成员个体的嗅闻及直立扫视动作时间比例、增大一般扫视、盯视及静听动作时间比例,降低觅食中断时间比例,提高其摄入率;而非亲缘家族群气味则能显著地延长家族群成员个体的觅食决定时间,通过增大家族群成员个体的嗅闻和一般扫视动作时间比例、减小直立扫视、盯视及静听动作时间比例,增大觅食中断时间比例,降低其摄入率。结果揭示,熟悉的社群气味会促使觅食活动中的家族群成员个体,在监测环境风险时,将精力更多地用于观察和监听群内其他成员个体的行为及其发出的警报信息,以便在有效规避环境风险的同时减缓个体间因干扰性竞争对觅食活动所造成的不利影响;而陌生的社群气味会迫使成员个体,将精力由依赖群内其他成员个体的行为...     

Reaction of alpha-mannosidase from Phaseolus vulgaris with group-specific reagents. Essential carboxyl groups.

When the pKm of alpha-mannosidase was determined at different pH values, the results indicated that ionizable groups with pK values of approx. 3.8 and 5.7 could be essential. Modification with carbodiimide or Woodward's Reagent K abolished the enzyme activity. The substrate analogue, alpha-methyl-D-mannoside, protected the enzyme against inactivation. Incorporation of a 14C-labeled nucleophile reagent in the presence or absence of the analogue suggested that 2--4 carboxyl groups were protected. Exchange studies indicated that the essential Zn2+ could be bound to such groups. There was no indication that hydroxyl groups, sulphydryl groups, guanidino groups or amino groups take part in the catalytic activity.     

Studies on the chemical stability of propylene glycol alginate esters

The chemical stability of propylene glycol alginates (PGAs) has been examined. Under acidic conditions the ester groups in PGA are stable to hydrolysis but hydrolytic degradation of the glycosidic linkages in the polysaccharide backbone occurs. Under alkaline conditions the ester groups are hydrolysed with the primary 2-hydroxyprop-1-yl ester groups being more susceptible than secondary 1-hydroxyprop-2-yl ester groups, with little degradation of the polysaccharide backbone. Sodium carbonate-bicarbonate buffer was a much more effective hydrolysing reagent than sodium hydroxide at the same concentration and pH, and the rate of hydrolysis was greatly accelerated by increasing the hydrolysis temperature. Acetate, citrate and phosphate ions accelerated the rate of hydrolysis of the ester groups in PGA when added to the sodium hydroxide hydrolysing reagent. Hydrolysis of the ester groups in PGA with sodium hydroxide was unaffected by the addition of imidazole. However hydrolysis of the ester groups in PGA with sodium hydroxide in the presence of 1-aminobutane led to the formation of an alginate amide in which only the primary 2-hydroxylprop-1-yl ester groups were present, suggesting that a nucleophilic substitution of primary ester groups by amine groups is involved in the reaction.     

The effects of group size and host species on development and survivorship of a gregarious caterpillar Halisidota caryae (Lepidoptera: Arctiidae)

Abstract. 1. The effect on growth and survivorship of the number of Halisidota caryae (Harris) caterpillars in groups feeding on three taxonomically distinct hosts was examined experimentally in the field.
2. Caterpillars grew more rapidly and survived better in larger sized groups than in smaller sized groups.
3. Caterpilliars grew more rapidly and survived better on Carya ovata (Koch) than on Hamamelis virginiana (L) or Quercus velutina (Lam.).
4. There were equal numbers of invertebrate predators on groups of different sizes and thus larger groups had significantly fewer predators per caterpillar than did smaller groups.
5. Invertebrate predators accounted for at least a 10% daily decrease in survivorship.
6. Local movement reduced predation because moving groups had fewer predators than did stationary groups.     

Effects of molecular structures on reduction properties of formyl groups in chlorophylls and pheophytins prepared from oxygenic photosynthetic organisms

Reduction of the 7-formyl groups in chlorophyll (Chl) b and its demetalated compound pheophytin (Phe) b was kinetically analyzed by using tert-butylamine-borane complex (t-BuNH(2)·BH(3)), and was compared with that of the 3-formyl groups in Chl d and Phe d. Reduction kinetics of the 7-formyl group in Chl b was similar to that in Phe b in dichloromethane containing 5mM t-BuNH(2)·BH(3). Little difference of the reduction kinetics of the 7-formyl groups between Chl b and Phe b was in sharp contrast to the reduction kinetics of the 3-formyl groups in Chl d and Phe d: the 3-formyl group in Phe d was reduced 5.3-fold faster than that in Chl d. The 7-formyl groups in Chl b and Phe b were reduced more slowly than the 3-formyl groups in Chl d and Phe d, respectively. The difference of the reactivity between the 3- and 7-formyl groups was in line with (13)C NMR measurements of chlorophyllous pigments, in which the chemical shifts of carbon atoms in the 7-formyl groups of Chl b and Phe b were high-field shifted compared with those in the 3-formyl groups of Chl d and Phe d, respectively. These indicate that the 7-formyl groups in chlorophyllous pigments were less reactive for reduction to the corresponding hydroxymethyl groups than the 3-formyl groups due to the difference in electronic states of the formyl groups in the A- and B-rings of the chlorin macrocycle.     

Synthesis and characterization of methylated poly(L-histidine) to control the stability of its siRNA polyion complexes for RNAi

Poly(L-histidine) (PLH) with dimethylimidazole groups has been synthesized as a pH-sensitive polypeptide to control the stability of its small interfering RNA (siRNA) polyion complexes for RNA interference (RNAi). The resulting methylated PLH (PLH-Me) was water-soluble despite deprotonation of the imidazole groups at physiological pH, as determined by acid-base titration and solution turbidity measurement. Agarose gel retardation assay proved that the quaternary dimethylimidazole groups worked as cationic groups to retain siRNA. The stability of the PLH-Me/siRNA complexes has depended on the content of hydrophobic groups, that is, τ/π-methylimidazole groups as well as deprotonated imidazole groups. PLH-Me exhibited no significant cytotoxicity despite the existence of cationic dimethylimidazole groups. By use of PLH-Me as a pH-sensitive siRNA carrier, the PLH-Me/siRNA complexes mediated efficient siRNA delivery attributed to the dimethylimidazole groups, and the gene silencing depended on the content balance among dimethyl, τ/π-methyl, and unmodified imidazole groups. These results suggest that PLH-Me controls the stability of siRNA polyion complexes by enhancing noncytotoxic siRNA delivery by optimizing the content balance of dimethyl, τ/π-methyl, and unmodified imidazole groups.     

Geographic patterns of genetic and morphological divergence amongst populations of a river crab (Decapoda, Potamonautidae) with the description of a new species from mountain streams in the Western Cape, South Africa

Recent systematic research has revealed that Potamonautes brincki comprises two genetically and morphologically distinct population groups. The systematic affinities between these population groups have remained uncertain. In the present study, the relationship between the population groups was examined. Eleven populations were collected from high mountain streams in the Western Cape, South Africa and used in the genetic and morphological analyses. Allozyme electrophoresis of 13 protein coding loci separated two main population groups: group A (Cape Peninsular groups) and group B (Hottentot's Holland) at I  = 0.73. Two additional genetic groups were evident, with group B being conspecific to group A, and group D being conspecific to group C. Morphological examination of pleopod 1 and the terminal segment of the mandibular palp showed considerable differences between the two main population groups, with groups A and B being similar and groups C and D being similar. The morphometric data for the four main groups were examined using discriminant functions analysis and the two main groups were compared using analyses of covariance. Discriminant functions analysis showed a moderate degree of overlap between the groups. Additional morphometric data showed a clear discrimination between the two main population groups. The genetic and morphometric data sets exhibited congruent patterns of variation and the data showed the presence of a species boundary. A new freshwater crab species, P. parvicorpus sp. n., is described. The results of the present study are discussed in the light of historical and contemporary factors that are likely to have contributed to speciation.     

Characterisation of Escherichia coli cell surface by isoelectric equilibrium analysis

A characterisation of the lipopolysaccharide (outermost) layer of Escherichia coli cells has been made by isoelectric equilibrium analysis. Unmodified E. coli cells show a surface isoelectric point (pI) of 5.6. Cells treated with ethyleneimine in order to esterify the carboxyl groups are isoelectric at pH 8.55. When amino groups are blocked the bacterial surface has a pI of 3.85. An analysis of these results suggests that the ionisable groups occurring in the isoelectric zone i.e. the zone amenable to investigation by the isoelectric equilibrium method are: carboxyl groups and amino groups of polysaccharide and protein components. The carboxyl groups have a pK between 3.2 and 4.5 and the amino groups have a pK of 7.5. ε-Amino groups, phenolic hydroxyl groups and guanidyl groups do not occur, and phosphate and amino groups of the phospholipid complex are not detected. The number of thiol groups in the isoelectric zone has been determined using 6,6′-dithiodinicotinic acid. The number of anionogenic and cationogenic groups has been determined. From the density of the negative charges on the surface it is estimated that the isoelectric zone might extend up to 60 Å below the cell surface. The data discussed in this paper relate to the outermost layer of the bacterial cell wall composed of lipopolysaccharide-phospholipid-protein complex. Since reactive groups of the phosphilipid component of the complex have not been detected in the isoelectric zone, it is suggested that the arrangement of lipopolysaccharide phospholipid protein complex is such that the phospholipids are located at a depth of more than 60 Å from the bacterial surface.     

Risk allocation and competition in foraging groups: reversed effects of competition if group size varies under risk of predation

Animals often feed more quickly when in larger groups. This group-size effect is often explained by safety advantages for groups but an alternative explanation is that animals feed faster in larger groups because of greater scramble competition for limited food. We show that predation risk enhances the group-size effect if groups vary in size. By contrast, competition leads to the group-size effect only when individuals feed in groups of constant size. When individuals feed in groups that vary in size, the best strategy for dealing with competition is to feed intensely when in smaller groups and feed little when in larger (more competitive) groups. In all situations, the effects of competition interact with the effects of predation risk in a simple multiplicative way. Our results suggest that scramble competition is not a general explanation for the group-size effect on vigilance in situations where group size changes relatively rapidly.     

Role of functional groups of human plasma and luminol in scavenging of NaOCl and neutrophil-derived hypochlorous acid

Hypochlorous acid HOCl/OCl^? and other oxidants derived from stimulated polymorphonuclear leukocytes are involved in tissue damage during a number of pathological processes. In order to obtain more detailed information on possible reactions of HOCl/OCl^? the effects of both NaOCl and PMN-derived hypochlorous acid on functional groups of amino acid solutions and human plasma are studied. In valine and lysine solutions NaOCl diminishes the number of amino groups in a molar ratio of 1:1 between NaOCl and amino groups. In cysteine and methionine samples the decrease of amino groups starts only after all sulfhydryl or thioether groups are oxidized by NaOCl. If freshly prepared human plasma is treated with increasing amounts of NaOCl all plasma SH groups are oxidized first, then probably the thioether groups and only after this the amino groups are affected. Furthermore, it was found, that the reactivity of luminol against NaOCl is similar to that of amino groups. Increasing amounts of SH groups of components of human plasma are oxidized by incubation with PMA-stimulated polymorphonuclear leukocytes dependent on the incubation time. Plasma amino groups are not affected under the same experimental conditions. The addition of plasma to FMLP-stimulated PMN in the presence of luminol decreases that part of chemiluminescence caused by extracellularly generated hypochlorous acid. Plasma samples pretreated with NaOCl cause a lower inhibition of light generation in FMLP-stimulated PMN only when more than 4 · 10^?8 mol NaOCl per mg protein are used to pretreat plasma. It is assumed that in the development of tissue injuries caused by infiltrated PMN the following sequence of damage occurs in accessible tissue regions. First, the sulfhydryl groups are oxidized, then the thioether groups, and only after this amino and other target groups are affected.     

Are indicator groups and cross-taxon congruence useful for predicting biodiversity in aquatic ecosystems?

Resources for biodiversity surveys and conservation planning are limited, and conservation biologists and environmental managers are thus striving to find suitable surrogates for mapping and predicting biodiversity. Among popular surrogates are indicator groups that could be used for predicting variation in the biodiversity of other taxonomic groups. Despite some success at large scales, surveys of multiple taxonomic groups across ecosystems have suggested that no single group can be used effectively to predict variation in the biodiversity of other taxonomic groups. This paper concentrates on indicator groups and cross-taxon congruence in species richness and assemblage composition patterns in inland aquatic ecosystems. As has been found in studies of terrestrial ecosystems, there is low utility for indicator groups in predicting the biodiversity of other taxa in aquatic ecosystems. Even when statistically highly significant correlations between taxonomic groups have been detected, these correlations have been too weak to provide reliable predictions of biodiversity among various taxonomic groups or biodiversity in general. Indicator groups and, more generally, cross-taxon congruence thus do not appear to be particularly relevant for conservation in the freshwater realm.     

Fitness consequences of sociality in prairie voles, Microtus ochrogaster: influence of group size and composition

We used 7 years of live-trapping data from an Illinois population of prairie voles to examine how survival and reproductive success varied with size and composition of social groups. Specifically, we examined measures of fitness for residents of single female units, male-female pairs and communal groups. Reproductive success, measured as either the number of young that survived to 12 or 30 days of age per adult female in a group, was higher for groups of three adults than for smaller or larger groups. The ideal group composition with respect to reproductive success appeared to be one adult female and two adult males. Individuals born into groups with three adults survived longer than did those born into smaller or larger groups. There was no clear relationship, however, between group size and survival of adult members of groups. Sudden disappearance of a group, presumably to predation by weasels, was associated with relative group size such that the largest groups were more likely to disappear. Overall, our data indicate that prairie voles living in communal groups with three adult members have higher fitness than those living in smaller groups or in larger communal groups. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.