Quantitative defense

Data from all three studies show that. In all cases, the terpene chemistry of young foliage, or qualitative defenses, was the most important factor In reducing budworm success. The protein complexlng capacity, or quantitative defenses, of this tissue was not Important In reducing budworm success In any of the studies. 

While quantitative defenses or digestibility reducing substances are also present In small quantities In the. young needles, they do not seem to be effective In reducing female dry weight, larval density, or level of defoliation. This Is consistent with the reasoning that young tissue development... 

Proteln-conq>lexlng polyphenols are broadly effective against herbivores, especially those not specifically adapted to eat plants containing polyphenols (47). They may constitute 10% or more of the leaf dry weight (12, 37, 44), and this requires allocation of significant amounts of carbon and energy to their construction. The use of limited reserves for such quantitative defenses must be balanced against the requirements of rapid canopy development and new shoot extension. 

Peeny (2) has coined the term "apparency" to express the Idea that some plants or plant cooponents are more predictable resources In space and time to potential herbivores. He suggests that such predictable plants are more attractive to specialist herbivores (In evolutionary time) because of their predictability, and thus should employ quantitative defensive compounds which are less susceptible to the evolution of detoxification mechanisms. 

Feeny (12-13) proposed the term "quantitative" defenses of plants for chemicals of low toxicity, such as tannins, constituting up to 60Z of the dry weight. Qualitative defenses Include allomones of high toxicity but usually present in low concentrations In plants (14). Most qualitative defenses occur In ephemeral or unapparent plants (annuals and short-lived perennials which are widely dispersed) and are designed to Interfere with Internal metabolism of herbivores, whereas most predictable or apparent plants (trees) rely on quantitative defenses such as tannins designed to reduce digestibility (2). NPA qualifies as a... 

Based on this type of reasoning, investigators have divided defensive substances into (1) the acute toxins (qualitative defenses) that are present in very low concentrations in plant tissues and which exert their effects on herbivores by interfering with some basic metabolic process such as transmission of nervous impulses, and (2) digestibility-reducing substances (quantitative defenses) that are present in higher concentrations in plant tissues, that act in the gut of the animal to reduce its ability to utilize its food, particularly proteins, and whose effectiveness increases directly with their concentration (Cates and Rhoades, 1977 Feeny, 1970, 1976 McKey, 1974 Rhoades and Cates, 1976). Qualitative defenses... 

On the one hand there are secondary products such as tannins (D 22.2.5 and D 22.3.3), resins (D 6.3), lignins (D 22.2.3) and calcium oxalate crystals (D 5) that act in a dosage-dependent fashion. These substances are often present in very high concentrations (quantitative defense). Tannins, which may reach... 

Barbehenn RV, Jaros A, Lee G, Mozola C, Weir Q, Salminen J-P (2009) Hydrolyzable tannins as quantitative defenses limited impact against Lymantria dispar caterpillars on hybrid poplar. J Insect Physiol 55 297-304... 

Since it is generally accepted that secondary plant constituents basically owe their existence to the selection by herbivores, microorganisms, etc., the dichotomy between alkaloids and tannins called for an explanation. To this end, various hypotheses were offered, which have been reviewed by Feeny (20). One was the "apparency hypothesis", which claimed that the more "apparent" or "predictable and available" plants should depend more on "quantitative" defense, i.e. tannins and other polyphenols, which were considered to be in principle non-detoxifiable. "Qualitative defense" involving smaller quantities of toxins such as alkaloids would then be the viable option for "unapparent" plants. However, these concepts have not been fully supported by observed patterns of predation. It seems that dso the postulated effects of tannins can be circumvented by various metabolic properties of the herbivore, and some tannins seem to be directly toxic to some consumers, in contrast to earlier postulates. Nonetheless, many recent studies have strengthened the view that tannins can act as strong deterrents for herbivores, perhaps because of their association with foliage of poor quality. 

Thus interpretations have undergone a shift (22). Initially defense patterns were interpreted from the point of view of the herbivore, which led to the distinction of qualititative and quantitative defense. Emphasis on the nutrient resources and plant metabolism then led to an amplification of Arens ideas in the "resource allocation hypothesis" (7 ), from which the distinction between immobile and mobile defense was derived. Somewhat different is the distinction between nitrogen-based and carbon-based defense (25), which exclusively is based on trophic conditions and may prove fiuitfiil in the context of forest ecology. 

The parent TMM precursor (1), now commercially available, has played a pivotal role in the execution of many synthetic plans directed at natural and unnatural targets. Reaction of (1) with 2-(methoxycarbonyl)cyclohexenone (14, R=C02Me) in the presence of palladium acetate and triethyl phosphite produced the adduct (15) in near quantitative yield. This cycloadduct is a critical intermediate in the total synthesis of a hydroxykempenone (16), a component of the defensive substances secreted by termites (Scheme 2.5) [12]. In accord with a previous observation by Trost that unactivated 2-cyclohexenone reacts poorly with TMM-Pd [13], the substrate (14, R=Me) was essentially inert in the cycloaddition. 

Commensal or environmental fungi that are typically harmless can become invasive mycoses when the host immune defenses are impaired. Host immune suppression and risk for opportunistic mycoses can be broadly classified into three categories (1) quantitative or qualitative deficits in neutrophil function, (2) deficits in cell-mediated immunity, and (3) disruption of mechanical/and or microbiologic barriers. 

There are various severity of illness scoring systems for sepsis and trauma (R11). Severity scoring can be used, in conjunction with other risk factors, to anticipate and evaluate outcomes, such as hospital mortality rate. The most widely used system is the Acute Physiology, Age, Chronic Health Evaluation II (APACHE II) classification system (K12). The APACHE III was developed to more accurately predict hospital mortality for critically ill hospitalized adults (K13). It provides objective probability estimates for critically ill hospitalized patients treated in intensive care units (ICUs). For critically ill posttrauma patients with sepsis or SIRS, another system for physiologic quantitative classification and severity stratification of the host defense response was described recently (R11). However, this Physiologic State Severity Classification (PSSC) has yet not been applied routinely in ICU setting. 

As a result, an EIA practitioner faces considerable difficulties while assessing impacts on ecosystems. On one hand, there are legal requirements to assess fully ecological effects and best practice recommendations to undertake quantitative assessments where possible. On the other hand, many assessors lack tools and techniques to undertake estimations with a high degree of confidence and prove them to be scientifically defensive. Of importance, there are formal RA techniques for tackling the uncertainty1 (first, data uncertainty) in a clear and explicit manner and its quantification, to increase impact predictability. 

In general, risk reduction is accomplished by implementing one or more protective layers, which reduce the frequency and/or consequence of the hazard scenario. LOPA provides specific criteria and restrictions for the evaluation of protection layers, eliminating the subjectivity of qualitative methods at substantially less cost than fully quantitative techniques. LOPA is a rational, defensible methodology that allows a rapid, cost-effective means for identifying the protection layers that lower the frequency and/or the consequence of specific hazard scenarios. 

Stamp N (2003) Out of the quagmire of plant defense hypotheses. Q Rev Biol 78 23-55 Steinberg PD (1988) Effects of quantitative and qualitative variation in phenolic compounds on feeding in 3 species of marine invertebrate herbivores. J Exp Mar Biol Ecol 120 221-237 Steinberg PD, de Nys R, Kjelleberg S (2002) Chemical cues for surface colonization. J Chem Ecol 28 1935-1951... 

In order to determine whether the defensive compounds of hybrids of the two Tribolium- species T.freemani and T. castaneum represent simple mixtures of the parental phenotypes, different glandular samples were compared by GC-MS [335]. Concerning the qualitative and quantitative data of the quinones,... 

Lactamases (EC 3.5.2.6) inactivate /3-lactam antibiotics by hydrolyzing the amide bond (Fig. 5.1, Pathway b). These enzymes are the most important ones in the bacterial defense against /3-lactam antibiotics [15]. On the basis of catalytic mechanism, /3-lactamases can be subdivided into two major groups, namely Zn2+-containing metalloproteins (class B), and active-serine enzymes, which are subdivided into classes A, C, and D based on their amino acid sequences (see Chapt. 2). The metallo-enzymes are produced by only a relatively small number of pathogenic strains, but represent a potential threat for the future. Indeed, they are able to hydrolyze efficiently carbape-nems, which generally escape the activity of the more common serine-/3-lac-tamases [16] [17]. At present, however, most of the resistance of bacteria to /3-lactam antibiotics is due to the activity of serine-/3-lactamases. These enzymes hydrolyze the /3-lactam moiety via an acyl-enzyme intermediate similar to that formed by transpeptidases. The difference in the catalytic pathways of the two enzymes is merely quantitative (Fig. 5.1, Pathways a and b). 

---